diff --git a/related_info/lab5/lab5-spoc-discuss/Makefile b/related_info/lab5/lab5-spoc-discuss/Makefile
new file mode 100644
index 0000000..3ebf64c
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/Makefile
@@ -0,0 +1,328 @@
+PROJ	:= 5
+EMPTY	:=
+SPACE	:= $(EMPTY) $(EMPTY)
+SLASH	:= /
+
+V       := @
+
+# try to infer the correct GCCPREFX
+ifndef GCCPREFIX
+GCCPREFIX := $(shell if i386-ucore-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-ucore-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-ucore-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-ucore-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-ucore-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-ucore-elf-', set your GCCPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# try to infer the correct QEMU
+ifndef QEMU
+QEMU := $(shell if which qemu-system-i386 > /dev/null; \
+	then echo 'qemu-system-i386'; exit; \
+	elif which i386-ucore-elf-qemu > /dev/null; \
+	then echo 'i386-ucore-elf-qemu'; exit; \
+	else \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# eliminate default suffix rules
+.SUFFIXES: .c .S .h
+
+# delete target files if there is an error (or make is interrupted)
+.DELETE_ON_ERROR:
+
+# define compiler and flags
+
+HOSTCC		:= gcc
+HOSTCFLAGS	:= -g -Wall -O2
+
+GDB		:= $(GCCPREFIX)gdb
+
+CC		?= $(GCCPREFIX)gcc
+CFLAGS	:= -fno-builtin -Wall -ggdb -m32 -gstabs -nostdinc $(DEFS)
+CFLAGS	+= $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+CTYPE	:= c S
+
+LD      := $(GCCPREFIX)ld
+LDFLAGS	:= -m $(shell $(LD) -V | grep elf_i386 2>/dev/null)
+LDFLAGS	+= -nostdlib
+
+OBJCOPY := $(GCCPREFIX)objcopy
+OBJDUMP := $(GCCPREFIX)objdump
+
+COPY	:= cp
+MKDIR   := mkdir -p
+MV		:= mv
+RM		:= rm -f
+AWK		:= awk
+SED		:= sed
+SH		:= sh
+TR		:= tr
+TOUCH	:= touch -c
+
+OBJDIR	:= obj
+BINDIR	:= bin
+
+ALLOBJS	:=
+ALLDEPS	:=
+TARGETS	:=
+
+include tools/function.mk
+
+listf_cc = $(call listf,$(1),$(CTYPE))
+
+USER_PREFIX	:= __user_
+
+# for cc
+add_files_cc = $(call add_files,$(1),$(CC),$(CFLAGS) $(3),$(2),$(4))
+create_target_cc = $(call create_target,$(1),$(2),$(3),$(CC),$(CFLAGS))
+
+# for hostcc
+add_files_host = $(call add_files,$(1),$(HOSTCC),$(HOSTCFLAGS),$(2),$(3))
+create_target_host = $(call create_target,$(1),$(2),$(3),$(HOSTCC),$(HOSTCFLAGS))
+
+cgtype = $(patsubst %.$(2),%.$(3),$(1))
+objfile = $(call toobj,$(1))
+asmfile = $(call cgtype,$(call toobj,$(1)),o,asm)
+outfile = $(call cgtype,$(call toobj,$(1)),o,out)
+symfile = $(call cgtype,$(call toobj,$(1)),o,sym)
+filename = $(basename $(notdir $(1)))
+ubinfile = $(call outfile,$(addprefix $(USER_PREFIX),$(call filename,$(1))))
+
+# for match pattern
+match = $(shell echo $(2) | $(AWK) '{for(i=1;i<=NF;i++){if(match("$(1)","^"$$(i)"$$")){exit 1;}}}'; echo $$?)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+# include kernel/user
+
+INCLUDE	+= libs/
+
+CFLAGS	+= $(addprefix -I,$(INCLUDE))
+
+LIBDIR	+= libs
+
+$(call add_files_cc,$(call listf_cc,$(LIBDIR)),libs,)
+
+# -------------------------------------------------------------------
+# user programs
+
+UINCLUDE	+= user/include/ \
+			   user/libs/
+
+USRCDIR		+= user
+
+ULIBDIR		+= user/libs
+
+UCFLAGS		+= $(addprefix -I,$(UINCLUDE))
+USER_BINS	:=
+
+$(call add_files_cc,$(call listf_cc,$(ULIBDIR)),ulibs,$(UCFLAGS))
+$(call add_files_cc,$(call listf_cc,$(USRCDIR)),uprog,$(UCFLAGS))
+
+UOBJS	:= $(call read_packet,ulibs libs)
+
+define uprog_ld
+__user_bin__ := $$(call ubinfile,$(1))
+USER_BINS += $$(__user_bin__)
+$$(__user_bin__): tools/user.ld
+$$(__user_bin__): $$(UOBJS)
+$$(__user_bin__): $(1) | $$$$(dir $$$$@)
+	$(V)$(LD) $(LDFLAGS) -T tools/user.ld -o $$@ $$(UOBJS) $(1)
+	@$(OBJDUMP) -S $$@ > $$(call cgtype,$$<,o,asm)
+	@$(OBJDUMP) -t $$@ | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$$$/d' > $$(call cgtype,$$<,o,sym)
+endef
+
+$(foreach p,$(call read_packet,uprog),$(eval $(call uprog_ld,$(p))))
+
+# -------------------------------------------------------------------
+# kernel
+
+KINCLUDE	+= kern/debug/ \
+			   kern/driver/ \
+			   kern/trap/ \
+			   kern/mm/ \
+			   kern/libs/ \
+			   kern/sync/ \
+			   kern/fs/    \
+			   kern/process \
+			   kern/schedule \
+			   kern/syscall
+
+KSRCDIR		+= kern/init \
+			   kern/libs \
+			   kern/debug \
+			   kern/driver \
+			   kern/trap \
+			   kern/mm \
+			   kern/sync \
+			   kern/fs    \
+			   kern/process \
+			   kern/schedule \
+			   kern/syscall
+
+KCFLAGS		+= $(addprefix -I,$(KINCLUDE))
+
+$(call add_files_cc,$(call listf_cc,$(KSRCDIR)),kernel,$(KCFLAGS))
+
+KOBJS	= $(call read_packet,kernel libs)
+
+# create kernel target
+kernel = $(call totarget,kernel)
+
+$(kernel): tools/kernel.ld
+
+$(kernel): $(KOBJS) $(USER_BINS)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -T tools/kernel.ld -o $@ $(KOBJS) -b binary $(USER_BINS)
+	@$(OBJDUMP) -S $@ > $(call asmfile,kernel)
+	@$(OBJDUMP) -t $@ | $(SED) '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $(call symfile,kernel)
+
+$(call create_target,kernel)
+
+# -------------------------------------------------------------------
+
+# create bootblock
+bootfiles = $(call listf_cc,boot)
+$(foreach f,$(bootfiles),$(call cc_compile,$(f),$(CC),$(CFLAGS) -Os -nostdinc))
+
+bootblock = $(call totarget,bootblock)
+
+$(bootblock): $(call toobj,boot/bootasm.S) $(call toobj,$(bootfiles)) | $(call totarget,sign)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -N -T tools/boot.ld $^ -o $(call toobj,bootblock)
+	@$(OBJDUMP) -S $(call objfile,bootblock) > $(call asmfile,bootblock)
+	@$(OBJCOPY) -S -O binary $(call objfile,bootblock) $(call outfile,bootblock)
+	@$(call totarget,sign) $(call outfile,bootblock) $(bootblock)
+
+$(call create_target,bootblock)
+
+# -------------------------------------------------------------------
+
+# create 'sign' tools
+$(call add_files_host,tools/sign.c,sign,sign)
+$(call create_target_host,sign,sign)
+
+# -------------------------------------------------------------------
+
+# create ucore.img
+UCOREIMG	:= $(call totarget,ucore.img)
+
+$(UCOREIMG): $(kernel) $(bootblock)
+	$(V)dd if=/dev/zero of=$@ count=10000
+	$(V)dd if=$(bootblock) of=$@ conv=notrunc
+	$(V)dd if=$(kernel) of=$@ seek=1 conv=notrunc
+
+$(call create_target,ucore.img)
+
+# -------------------------------------------------------------------
+
+# create swap.img
+SWAPIMG		:= $(call totarget,swap.img)
+
+$(SWAPIMG):
+	$(V)dd if=/dev/zero of=$@ bs=1M count=128
+
+$(call create_target,swap.img)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+$(call finish_all)
+
+IGNORE_ALLDEPS	= clean \
+				  dist-clean \
+				  grade \
+				  touch \
+				  print-.+ \
+				  run-.+ \
+				  build-.+ \
+				  handin
+
+ifeq ($(call match,$(MAKECMDGOALS),$(IGNORE_ALLDEPS)),0)
+-include $(ALLDEPS)
+endif
+
+# files for grade script
+
+TARGETS: $(TARGETS)
+
+.DEFAULT_GOAL := TARGETS
+
+QEMUOPTS = -hda $(UCOREIMG) -drive file=$(SWAPIMG),media=disk,cache=writeback
+
+.PHONY: qemu qemu-nox debug debug-nox
+qemu-mon: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -monitor stdio $(QEMUOPTS) -serial null
+qemu: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -parallel stdio $(QEMUOPTS) -serial null
+
+qemu-nox: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -serial mon:stdio $(QEMUOPTS) -nographic
+
+TERMINAL := gnome-terminal
+
+debug: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -S -s -parallel stdio $(QEMUOPTS) -serial null &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "$(GDB) -q -x tools/gdbinit"
+
+debug-nox: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -S -s -serial mon:stdio $(QEMUOPTS) -nographic &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "$(GDB) -q -x tools/gdbinit"
+
+RUN_PREFIX	:= _binary_$(OBJDIR)_$(USER_PREFIX)
+MAKEOPTS	:= --quiet --no-print-directory
+
+run-%: build-%
+	$(V)$(QEMU) -parallel stdio $(QEMUOPTS) -serial null
+
+run-nox-%: build-%
+	$(V)$(QEMU) -serial mon:stdio $(QEMUOPTS) -nographic
+
+build-%: touch
+	$(V)$(MAKE) $(MAKEOPTS) "DEFS+=-DTEST=$* -DTESTSTART=$(RUN_PREFIX)$*_out_start -DTESTSIZE=$(RUN_PREFIX)$*_out_size"
+
+.PHONY: grade touch
+
+GRADE_GDB_IN	:= .gdb.in
+GRADE_QEMU_OUT	:= .qemu.out
+HANDIN			:= proj$(PROJ)-handin.tar.gz
+
+TOUCH_FILES		:= kern/process/proc.c
+
+MAKEOPTS		:= --quiet --no-print-directory
+
+grade:
+	$(V)$(MAKE) $(MAKEOPTS) clean
+	$(V)$(SH) tools/grade.sh
+
+touch:
+	$(V)$(foreach f,$(TOUCH_FILES),$(TOUCH) $(f))
+
+print-%:
+	@echo $($(shell echo $(patsubst print-%,%,$@) | $(TR) [a-z] [A-Z]))
+
+.PHONY: clean dist-clean handin packall
+clean:
+	$(V)$(RM) $(GRADE_GDB_IN) $(GRADE_QEMU_OUT)
+	-$(RM) -r $(OBJDIR) $(BINDIR)
+
+dist-clean: clean
+	-$(RM) $(HANDIN)
+
+handin: packall
+	@echo Please visit http://learn.tsinghua.edu.cn and upload $(HANDIN). Thanks!
+
+packall: clean
+	@$(RM) -f $(HANDIN)
+	@tar -czf $(HANDIN) `find . -type f -o -type d | grep -v '^\.*$$' | grep -vF '$(HANDIN)'`
+
diff --git a/related_info/lab5/lab5-spoc-discuss/boot/asm.h b/related_info/lab5/lab5-spoc-discuss/boot/asm.h
new file mode 100644
index 0000000..8e0405a
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/boot/asm.h
@@ -0,0 +1,26 @@
+#ifndef __BOOT_ASM_H__
+#define __BOOT_ASM_H__
+
+/* Assembler macros to create x86 segments */
+
+/* Normal segment */
+#define SEG_NULLASM                                             \
+    .word 0, 0;                                                 \
+    .byte 0, 0, 0, 0
+
+#define SEG_ASM(type,base,lim)                                  \
+    .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);          \
+    .byte (((base) >> 16) & 0xff), (0x90 | (type)),             \
+        (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
+
+
+/* Application segment type bits */
+#define STA_X       0x8     // Executable segment
+#define STA_E       0x4     // Expand down (non-executable segments)
+#define STA_C       0x4     // Conforming code segment (executable only)
+#define STA_W       0x2     // Writeable (non-executable segments)
+#define STA_R       0x2     // Readable (executable segments)
+#define STA_A       0x1     // Accessed
+
+#endif /* !__BOOT_ASM_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/boot/bootasm.S b/related_info/lab5/lab5-spoc-discuss/boot/bootasm.S
new file mode 100644
index 0000000..f1852c3
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/boot/bootasm.S
@@ -0,0 +1,107 @@
+#include <asm.h>
+
+# Start the CPU: switch to 32-bit protected mode, jump into C.
+# The BIOS loads this code from the first sector of the hard disk into
+# memory at physical address 0x7c00 and starts executing in real mode
+# with %cs=0 %ip=7c00.
+
+.set PROT_MODE_CSEG,        0x8                     # kernel code segment selector
+.set PROT_MODE_DSEG,        0x10                    # kernel data segment selector
+.set CR0_PE_ON,             0x1                     # protected mode enable flag
+.set SMAP,                  0x534d4150
+
+# start address should be 0:7c00, in real mode, the beginning address of the running bootloader
+.globl start
+start:
+.code16                                             # Assemble for 16-bit mode
+    cli                                             # Disable interrupts
+    cld                                             # String operations increment
+
+    # Set up the important data segment registers (DS, ES, SS).
+    xorw %ax, %ax                                   # Segment number zero
+    movw %ax, %ds                                   # -> Data Segment
+    movw %ax, %es                                   # -> Extra Segment
+    movw %ax, %ss                                   # -> Stack Segment
+
+    # Enable A20:
+    #  For backwards compatibility with the earliest PCs, physical
+    #  address line 20 is tied low, so that addresses higher than
+    #  1MB wrap around to zero by default. This code undoes this.
+seta20.1:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.1
+
+    movb $0xd1, %al                                 # 0xd1 -> port 0x64
+    outb %al, $0x64
+
+seta20.2:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.2
+
+    movb $0xdf, %al                                 # 0xdf -> port 0x60
+    outb %al, $0x60
+
+probe_memory:
+    movl $0, 0x8000
+    xorl %ebx, %ebx
+    movw $0x8004, %di
+start_probe:
+    movl $0xE820, %eax
+    movl $20, %ecx
+    movl $SMAP, %edx
+    int $0x15
+    jnc cont
+    movw $12345, 0x8000
+    jmp finish_probe
+cont:
+    addw $20, %di
+    incl 0x8000
+    cmpl $0, %ebx
+    jnz start_probe
+finish_probe:
+
+    # Switch from real to protected mode, using a bootstrap GDT
+    # and segment translation that makes virtual addresses
+    # identical to physical addresses, so that the
+    # effective memory map does not change during the switch.
+    lgdt gdtdesc
+    movl %cr0, %eax
+    orl $CR0_PE_ON, %eax
+    movl %eax, %cr0
+
+    # Jump to next instruction, but in 32-bit code segment.
+    # Switches processor into 32-bit mode.
+    ljmp $PROT_MODE_CSEG, $protcseg
+
+.code32                                             # Assemble for 32-bit mode
+protcseg:
+    # Set up the protected-mode data segment registers
+    movw $PROT_MODE_DSEG, %ax                       # Our data segment selector
+    movw %ax, %ds                                   # -> DS: Data Segment
+    movw %ax, %es                                   # -> ES: Extra Segment
+    movw %ax, %fs                                   # -> FS
+    movw %ax, %gs                                   # -> GS
+    movw %ax, %ss                                   # -> SS: Stack Segment
+
+    # Set up the stack pointer and call into C. The stack region is from 0--start(0x7c00)
+    movl $0x0, %ebp
+    movl $start, %esp
+    call bootmain
+
+    # If bootmain returns (it shouldn't), loop.
+spin:
+    jmp spin
+
+.data
+# Bootstrap GDT
+.p2align 2                                          # force 4 byte alignment
+gdt:
+    SEG_NULLASM                                     # null seg
+    SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff)           # code seg for bootloader and kernel
+    SEG_ASM(STA_W, 0x0, 0xffffffff)                 # data seg for bootloader and kernel
+
+gdtdesc:
+    .word 0x17                                      # sizeof(gdt) - 1
+    .long gdt                                       # address gdt
diff --git a/related_info/lab5/lab5-spoc-discuss/boot/bootmain.c b/related_info/lab5/lab5-spoc-discuss/boot/bootmain.c
new file mode 100644
index 0000000..4b55eb7
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/boot/bootmain.c
@@ -0,0 +1,116 @@
+#include <defs.h>
+#include <x86.h>
+#include <elf.h>
+
+/* *********************************************************************
+ * This a dirt simple boot loader, whose sole job is to boot
+ * an ELF kernel image from the first IDE hard disk.
+ *
+ * DISK LAYOUT
+ *  * This program(bootasm.S and bootmain.c) is the bootloader.
+ *    It should be stored in the first sector of the disk.
+ *
+ *  * The 2nd sector onward holds the kernel image.
+ *
+ *  * The kernel image must be in ELF format.
+ *
+ * BOOT UP STEPS
+ *  * when the CPU boots it loads the BIOS into memory and executes it
+ *
+ *  * the BIOS intializes devices, sets of the interrupt routines, and
+ *    reads the first sector of the boot device(e.g., hard-drive)
+ *    into memory and jumps to it.
+ *
+ *  * Assuming this boot loader is stored in the first sector of the
+ *    hard-drive, this code takes over...
+ *
+ *  * control starts in bootasm.S -- which sets up protected mode,
+ *    and a stack so C code then run, then calls bootmain()
+ *
+ *  * bootmain() in this file takes over, reads in the kernel and jumps to it.
+ * */
+
+#define SECTSIZE        512
+#define ELFHDR          ((struct elfhdr *)0x10000)      // scratch space
+
+/* waitdisk - wait for disk ready */
+static void
+waitdisk(void) {
+    while ((inb(0x1F7) & 0xC0) != 0x40)
+        /* do nothing */;
+}
+
+/* readsect - read a single sector at @secno into @dst */
+static void
+readsect(void *dst, uint32_t secno) {
+    // wait for disk to be ready
+    waitdisk();
+
+    outb(0x1F2, 1);                         // count = 1
+    outb(0x1F3, secno & 0xFF);
+    outb(0x1F4, (secno >> 8) & 0xFF);
+    outb(0x1F5, (secno >> 16) & 0xFF);
+    outb(0x1F6, ((secno >> 24) & 0xF) | 0xE0);
+    outb(0x1F7, 0x20);                      // cmd 0x20 - read sectors
+
+    // wait for disk to be ready
+    waitdisk();
+
+    // read a sector
+    insl(0x1F0, dst, SECTSIZE / 4);
+}
+
+/* *
+ * readseg - read @count bytes at @offset from kernel into virtual address @va,
+ * might copy more than asked.
+ * */
+static void
+readseg(uintptr_t va, uint32_t count, uint32_t offset) {
+    uintptr_t end_va = va + count;
+
+    // round down to sector boundary
+    va -= offset % SECTSIZE;
+
+    // translate from bytes to sectors; kernel starts at sector 1
+    uint32_t secno = (offset / SECTSIZE) + 1;
+
+    // If this is too slow, we could read lots of sectors at a time.
+    // We'd write more to memory than asked, but it doesn't matter --
+    // we load in increasing order.
+    for (; va < end_va; va += SECTSIZE, secno ++) {
+        readsect((void *)va, secno);
+    }
+}
+
+/* bootmain - the entry of bootloader */
+void
+bootmain(void) {
+    // read the 1st page off disk
+    readseg((uintptr_t)ELFHDR, SECTSIZE * 8, 0);
+
+    // is this a valid ELF?
+    if (ELFHDR->e_magic != ELF_MAGIC) {
+        goto bad;
+    }
+
+    struct proghdr *ph, *eph;
+
+    // load each program segment (ignores ph flags)
+    ph = (struct proghdr *)((uintptr_t)ELFHDR + ELFHDR->e_phoff);
+    eph = ph + ELFHDR->e_phnum;
+    for (; ph < eph; ph ++) {
+        readseg(ph->p_va & 0xFFFFFF, ph->p_memsz, ph->p_offset);
+    }
+
+    // call the entry point from the ELF header
+    // note: does not return
+    ((void (*)(void))(ELFHDR->e_entry & 0xFFFFFF))();
+
+bad:
+    outw(0x8A00, 0x8A00);
+    outw(0x8A00, 0x8E00);
+
+    /* do nothing */
+    while (1);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/assert.h b/related_info/lab5/lab5-spoc-discuss/kern/debug/assert.h
new file mode 100644
index 0000000..ac1a966
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/assert.h
@@ -0,0 +1,27 @@
+#ifndef __KERN_DEBUG_ASSERT_H__
+#define __KERN_DEBUG_ASSERT_H__
+
+#include <defs.h>
+
+void __warn(const char *file, int line, const char *fmt, ...);
+void __noreturn __panic(const char *file, int line, const char *fmt, ...);
+
+#define warn(...)                                       \
+    __warn(__FILE__, __LINE__, __VA_ARGS__)
+
+#define panic(...)                                      \
+    __panic(__FILE__, __LINE__, __VA_ARGS__)
+
+#define assert(x)                                       \
+    do {                                                \
+        if (!(x)) {                                     \
+            panic("assertion failed: %s", #x);          \
+        }                                               \
+    } while (0)
+
+// static_assert(x) will generate a compile-time error if 'x' is false.
+#define static_assert(x)                                \
+    switch (x) { case 0: case (x): ; }
+
+#endif /* !__KERN_DEBUG_ASSERT_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.c b/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.c
new file mode 100644
index 0000000..e3149a5
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.c
@@ -0,0 +1,365 @@
+#include <defs.h>
+#include <x86.h>
+#include <stab.h>
+#include <stdio.h>
+#include <string.h>
+#include <memlayout.h>
+#include <sync.h>
+#include <vmm.h>
+#include <proc.h>
+#include <kdebug.h>
+#include <kmonitor.h>
+#include <assert.h>
+
+#define STACKFRAME_DEPTH 20
+
+extern const struct stab __STAB_BEGIN__[];  // beginning of stabs table
+extern const struct stab __STAB_END__[];    // end of stabs table
+extern const char __STABSTR_BEGIN__[];      // beginning of string table
+extern const char __STABSTR_END__[];        // end of string table
+
+/* debug information about a particular instruction pointer */
+struct eipdebuginfo {
+    const char *eip_file;                   // source code filename for eip
+    int eip_line;                           // source code line number for eip
+    const char *eip_fn_name;                // name of function containing eip
+    int eip_fn_namelen;                     // length of function's name
+    uintptr_t eip_fn_addr;                  // start address of function
+    int eip_fn_narg;                        // number of function arguments
+};
+
+/* user STABS data structure  */
+struct userstabdata {
+    const struct stab *stabs;
+    const struct stab *stab_end;
+    const char *stabstr;
+    const char *stabstr_end;
+};
+
+/* *
+ * stab_binsearch - according to the input, the initial value of
+ * range [*@region_left, *@region_right], find a single stab entry
+ * that includes the address @addr and matches the type @type,
+ * and then save its boundary to the locations that pointed
+ * by @region_left and @region_right.
+ *
+ * Some stab types are arranged in increasing order by instruction address.
+ * For example, N_FUN stabs (stab entries with n_type == N_FUN), which
+ * mark functions, and N_SO stabs, which mark source files.
+ *
+ * Given an instruction address, this function finds the single stab entry
+ * of type @type that contains that address.
+ *
+ * The search takes place within the range [*@region_left, *@region_right].
+ * Thus, to search an entire set of N stabs, you might do:
+ *
+ *      left = 0;
+ *      right = N - 1;    (rightmost stab)
+ *      stab_binsearch(stabs, &left, &right, type, addr);
+ *
+ * The search modifies *region_left and *region_right to bracket the @addr.
+ * *@region_left points to the matching stab that contains @addr,
+ * and *@region_right points just before the next stab.
+ * If *@region_left > *region_right, then @addr is not contained in any
+ * matching stab.
+ *
+ * For example, given these N_SO stabs:
+ *      Index  Type   Address
+ *      0      SO     f0100000
+ *      13     SO     f0100040
+ *      117    SO     f0100176
+ *      118    SO     f0100178
+ *      555    SO     f0100652
+ *      556    SO     f0100654
+ *      657    SO     f0100849
+ * this code:
+ *      left = 0, right = 657;
+ *      stab_binsearch(stabs, &left, &right, N_SO, 0xf0100184);
+ * will exit setting left = 118, right = 554.
+ * */
+static void
+stab_binsearch(const struct stab *stabs, int *region_left, int *region_right,
+           int type, uintptr_t addr) {
+    int l = *region_left, r = *region_right, any_matches = 0;
+
+    while (l <= r) {
+        int true_m = (l + r) / 2, m = true_m;
+
+        // search for earliest stab with right type
+        while (m >= l && stabs[m].n_type != type) {
+            m --;
+        }
+        if (m < l) {    // no match in [l, m]
+            l = true_m + 1;
+            continue;
+        }
+
+        // actual binary search
+        any_matches = 1;
+        if (stabs[m].n_value < addr) {
+            *region_left = m;
+            l = true_m + 1;
+        } else if (stabs[m].n_value > addr) {
+            *region_right = m - 1;
+            r = m - 1;
+        } else {
+            // exact match for 'addr', but continue loop to find
+            // *region_right
+            *region_left = m;
+            l = m;
+            addr ++;
+        }
+    }
+
+    if (!any_matches) {
+        *region_right = *region_left - 1;
+    }
+    else {
+        // find rightmost region containing 'addr'
+        l = *region_right;
+        for (; l > *region_left && stabs[l].n_type != type; l --)
+            /* do nothing */;
+        *region_left = l;
+    }
+}
+
+/* *
+ * debuginfo_eip - Fill in the @info structure with information about
+ * the specified instruction address, @addr.  Returns 0 if information
+ * was found, and negative if not.  But even if it returns negative it
+ * has stored some information into '*info'.
+ * */
+int
+debuginfo_eip(uintptr_t addr, struct eipdebuginfo *info) {
+    const struct stab *stabs, *stab_end;
+    const char *stabstr, *stabstr_end;
+
+    info->eip_file = "<unknown>";
+    info->eip_line = 0;
+    info->eip_fn_name = "<unknown>";
+    info->eip_fn_namelen = 9;
+    info->eip_fn_addr = addr;
+    info->eip_fn_narg = 0;
+
+    // find the relevant set of stabs
+    if (addr >= KERNBASE) {
+        stabs = __STAB_BEGIN__;
+        stab_end = __STAB_END__;
+        stabstr = __STABSTR_BEGIN__;
+        stabstr_end = __STABSTR_END__;
+    }
+    else {
+        // user-program linker script, tools/user.ld puts the information about the
+        // program's stabs (included __STAB_BEGIN__, __STAB_END__, __STABSTR_BEGIN__,
+        // and __STABSTR_END__) in a structure located at virtual address USTAB.
+        const struct userstabdata *usd = (struct userstabdata *)USTAB;
+
+        // make sure that debugger (current process) can access this memory
+        struct mm_struct *mm;
+        if (current == NULL || (mm = current->mm) == NULL) {
+            return -1;
+        }
+        if (!user_mem_check(mm, (uintptr_t)usd, sizeof(struct userstabdata), 0)) {
+            return -1;
+        }
+
+        stabs = usd->stabs;
+        stab_end = usd->stab_end;
+        stabstr = usd->stabstr;
+        stabstr_end = usd->stabstr_end;
+
+        // make sure the STABS and string table memory is valid
+        if (!user_mem_check(mm, (uintptr_t)stabs, (uintptr_t)stab_end - (uintptr_t)stabs, 0)) {
+            return -1;
+        }
+        if (!user_mem_check(mm, (uintptr_t)stabstr, stabstr_end - stabstr, 0)) {
+            return -1;
+        }
+    }
+
+    // String table validity checks
+    if (stabstr_end <= stabstr || stabstr_end[-1] != 0) {
+        return -1;
+    }
+
+    // Now we find the right stabs that define the function containing
+    // 'eip'.  First, we find the basic source file containing 'eip'.
+    // Then, we look in that source file for the function.  Then we look
+    // for the line number.
+
+    // Search the entire set of stabs for the source file (type N_SO).
+    int lfile = 0, rfile = (stab_end - stabs) - 1;
+    stab_binsearch(stabs, &lfile, &rfile, N_SO, addr);
+    if (lfile == 0)
+        return -1;
+
+    // Search within that file's stabs for the function definition
+    // (N_FUN).
+    int lfun = lfile, rfun = rfile;
+    int lline, rline;
+    stab_binsearch(stabs, &lfun, &rfun, N_FUN, addr);
+
+    if (lfun <= rfun) {
+        // stabs[lfun] points to the function name
+        // in the string table, but check bounds just in case.
+        if (stabs[lfun].n_strx < stabstr_end - stabstr) {
+            info->eip_fn_name = stabstr + stabs[lfun].n_strx;
+        }
+        info->eip_fn_addr = stabs[lfun].n_value;
+        addr -= info->eip_fn_addr;
+        // Search within the function definition for the line number.
+        lline = lfun;
+        rline = rfun;
+    } else {
+        // Couldn't find function stab!  Maybe we're in an assembly
+        // file.  Search the whole file for the line number.
+        info->eip_fn_addr = addr;
+        lline = lfile;
+        rline = rfile;
+    }
+    info->eip_fn_namelen = strfind(info->eip_fn_name, ':') - info->eip_fn_name;
+
+    // Search within [lline, rline] for the line number stab.
+    // If found, set info->eip_line to the right line number.
+    // If not found, return -1.
+    stab_binsearch(stabs, &lline, &rline, N_SLINE, addr);
+    if (lline <= rline) {
+        info->eip_line = stabs[rline].n_desc;
+    } else {
+        return -1;
+    }
+
+    // Search backwards from the line number for the relevant filename stab.
+    // We can't just use the "lfile" stab because inlined functions
+    // can interpolate code from a different file!
+    // Such included source files use the N_SOL stab type.
+    while (lline >= lfile
+           && stabs[lline].n_type != N_SOL
+           && (stabs[lline].n_type != N_SO || !stabs[lline].n_value)) {
+        lline --;
+    }
+    if (lline >= lfile && stabs[lline].n_strx < stabstr_end - stabstr) {
+        info->eip_file = stabstr + stabs[lline].n_strx;
+    }
+
+    // Set eip_fn_narg to the number of arguments taken by the function,
+    // or 0 if there was no containing function.
+    if (lfun < rfun) {
+        for (lline = lfun + 1;
+             lline < rfun && stabs[lline].n_type == N_PSYM;
+             lline ++) {
+            info->eip_fn_narg ++;
+        }
+    }
+    return 0;
+}
+
+/* *
+ * print_kerninfo - print the information about kernel, including the location
+ * of kernel entry, the start addresses of data and text segements, the start
+ * address of free memory and how many memory that kernel has used.
+ * */
+void
+print_kerninfo(void) {
+    extern char etext[], edata[], end[], kern_init[];
+    cprintf("Special kernel symbols:\n");
+    cprintf("  entry  0x%08x (phys)\n", kern_init);
+    cprintf("  etext  0x%08x (phys)\n", etext);
+    cprintf("  edata  0x%08x (phys)\n", edata);
+    cprintf("  end    0x%08x (phys)\n", end);
+    cprintf("Kernel executable memory footprint: %dKB\n", (end - kern_init + 1023)/1024);
+}
+
+/* *
+ * print_debuginfo - read and print the stat information for the address @eip,
+ * and info.eip_fn_addr should be the first address of the related function.
+ * */
+void
+print_debuginfo(uintptr_t eip) {
+    struct eipdebuginfo info;
+    if (debuginfo_eip(eip, &info) != 0) {
+        cprintf("    <unknow>: -- 0x%08x --\n", eip);
+    }
+    else {
+        char fnname[256];
+        int j;
+        for (j = 0; j < info.eip_fn_namelen; j ++) {
+            fnname[j] = info.eip_fn_name[j];
+        }
+        fnname[j] = '\0';
+        cprintf("    %s:%d: %s+%d\n", info.eip_file, info.eip_line,
+                fnname, eip - info.eip_fn_addr);
+    }
+}
+
+static __noinline uint32_t
+read_eip(void) {
+    uint32_t eip;
+    asm volatile("movl 4(%%ebp), %0" : "=r" (eip));
+    return eip;
+}
+
+/* *
+ * print_stackframe - print a list of the saved eip values from the nested 'call'
+ * instructions that led to the current point of execution
+ *
+ * The x86 stack pointer, namely esp, points to the lowest location on the stack
+ * that is currently in use. Everything below that location in stack is free. Pushing
+ * a value onto the stack will invole decreasing the stack pointer and then writing
+ * the value to the place that stack pointer pointes to. And popping a value do the
+ * opposite.
+ *
+ * The ebp (base pointer) register, in contrast, is associated with the stack
+ * primarily by software convention. On entry to a C function, the function's
+ * prologue code normally saves the previous function's base pointer by pushing
+ * it onto the stack, and then copies the current esp value into ebp for the duration
+ * of the function. If all the functions in a program obey this convention,
+ * then at any given point during the program's execution, it is possible to trace
+ * back through the stack by following the chain of saved ebp pointers and determining
+ * exactly what nested sequence of function calls caused this particular point in the
+ * program to be reached. This capability can be particularly useful, for example,
+ * when a particular function causes an assert failure or panic because bad arguments
+ * were passed to it, but you aren't sure who passed the bad arguments. A stack
+ * backtrace lets you find the offending function.
+ *
+ * The inline function read_ebp() can tell us the value of current ebp. And the
+ * non-inline function read_eip() is useful, it can read the value of current eip,
+ * since while calling this function, read_eip() can read the caller's eip from
+ * stack easily.
+ *
+ * In print_debuginfo(), the function debuginfo_eip() can get enough information about
+ * calling-chain. Finally print_stackframe() will trace and print them for debugging.
+ *
+ * Note that, the length of ebp-chain is limited. In boot/bootasm.S, before jumping
+ * to the kernel entry, the value of ebp has been set to zero, that's the boundary.
+ * */
+void
+print_stackframe(void) {
+     /* LAB1 YOUR CODE : STEP 1 */
+     /* (1) call read_ebp() to get the value of ebp. the type is (uint32_t);
+      * (2) call read_eip() to get the value of eip. the type is (uint32_t);
+      * (3) from 0 .. STACKFRAME_DEPTH
+      *    (3.1) printf value of ebp, eip
+      *    (3.2) (uint32_t)calling arguments [0..4] = the contents in address (unit32_t)ebp +2 [0..4]
+      *    (3.3) cprintf("\n");
+      *    (3.4) call print_debuginfo(eip-1) to print the C calling function name and line number, etc.
+      *    (3.5) popup a calling stackframe
+      *           NOTICE: the calling funciton's return addr eip  = ss:[ebp+4]
+      *                   the calling funciton's ebp = ss:[ebp]
+      */
+    uint32_t ebp = read_ebp(), eip = read_eip();
+
+    int i, j;
+    for (i = 0; ebp != 0 && i < STACKFRAME_DEPTH; i ++) {
+        cprintf("ebp:0x%08x eip:0x%08x args:", ebp, eip);
+        uint32_t *args = (uint32_t *)ebp + 2;
+        for (j = 0; j < 4; j ++) {
+            cprintf("0x%08x ", args[j]);
+        }
+        cprintf("\n");
+        print_debuginfo(eip - 1);
+        eip = ((uint32_t *)ebp)[1];
+        ebp = ((uint32_t *)ebp)[0];
+    }
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.h b/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.h
new file mode 100644
index 0000000..c2a7b74
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/kdebug.h
@@ -0,0 +1,12 @@
+#ifndef __KERN_DEBUG_KDEBUG_H__
+#define __KERN_DEBUG_KDEBUG_H__
+
+#include <defs.h>
+#include <trap.h>
+
+void print_kerninfo(void);
+void print_stackframe(void);
+void print_debuginfo(uintptr_t eip);
+
+#endif /* !__KERN_DEBUG_KDEBUG_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.c b/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.c
new file mode 100644
index 0000000..af7c401
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.c
@@ -0,0 +1,132 @@
+#include <stdio.h>
+#include <string.h>
+#include <mmu.h>
+#include <trap.h>
+#include <kmonitor.h>
+#include <kdebug.h>
+
+/* *
+ * Simple command-line kernel monitor useful for controlling the
+ * kernel and exploring the system interactively.
+ * */
+
+struct command {
+    const char *name;
+    const char *desc;
+    // return -1 to force monitor to exit
+    int(*func)(int argc, char **argv, struct trapframe *tf);
+};
+
+static struct command commands[] = {
+    {"help", "Display this list of commands.", mon_help},
+    {"kerninfo", "Display information about the kernel.", mon_kerninfo},
+    {"backtrace", "Print backtrace of stack frame.", mon_backtrace},
+};
+
+/* return if kernel is panic, in kern/debug/panic.c */
+bool is_kernel_panic(void);
+
+#define NCOMMANDS (sizeof(commands)/sizeof(struct command))
+
+/***** Kernel monitor command interpreter *****/
+
+#define MAXARGS         16
+#define WHITESPACE      " \t\n\r"
+
+/* parse - parse the command buffer into whitespace-separated arguments */
+static int
+parse(char *buf, char **argv) {
+    int argc = 0;
+    while (1) {
+        // find global whitespace
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) != NULL) {
+            *buf ++ = '\0';
+        }
+        if (*buf == '\0') {
+            break;
+        }
+
+        // save and scan past next arg
+        if (argc == MAXARGS - 1) {
+            cprintf("Too many arguments (max %d).\n", MAXARGS);
+        }
+        argv[argc ++] = buf;
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) == NULL) {
+            buf ++;
+        }
+    }
+    return argc;
+}
+
+/* *
+ * runcmd - parse the input string, split it into separated arguments
+ * and then lookup and invoke some related commands/
+ * */
+static int
+runcmd(char *buf, struct trapframe *tf) {
+    char *argv[MAXARGS];
+    int argc = parse(buf, argv);
+    if (argc == 0) {
+        return 0;
+    }
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        if (strcmp(commands[i].name, argv[0]) == 0) {
+            return commands[i].func(argc - 1, argv + 1, tf);
+        }
+    }
+    cprintf("Unknown command '%s'\n", argv[0]);
+    return 0;
+}
+
+/***** Implementations of basic kernel monitor commands *****/
+
+void
+kmonitor(struct trapframe *tf) {
+    cprintf("Welcome to the kernel debug monitor!!\n");
+    cprintf("Type 'help' for a list of commands.\n");
+
+    if (tf != NULL) {
+        print_trapframe(tf);
+    }
+
+    char *buf;
+    while (1) {
+        if ((buf = readline("K> ")) != NULL) {
+            if (runcmd(buf, tf) < 0) {
+                break;
+            }
+        }
+    }
+}
+
+/* mon_help - print the information about mon_* functions */
+int
+mon_help(int argc, char **argv, struct trapframe *tf) {
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        cprintf("%s - %s\n", commands[i].name, commands[i].desc);
+    }
+    return 0;
+}
+
+/* *
+ * mon_kerninfo - call print_kerninfo in kern/debug/kdebug.c to
+ * print the memory occupancy in kernel.
+ * */
+int
+mon_kerninfo(int argc, char **argv, struct trapframe *tf) {
+    print_kerninfo();
+    return 0;
+}
+
+/* *
+ * mon_backtrace - call print_stackframe in kern/debug/kdebug.c to
+ * print a backtrace of the stack.
+ * */
+int
+mon_backtrace(int argc, char **argv, struct trapframe *tf) {
+    print_stackframe();
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.h b/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.h
new file mode 100644
index 0000000..67dfe64
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/kmonitor.h
@@ -0,0 +1,19 @@
+#ifndef __KERN_DEBUG_MONITOR_H__
+#define __KERN_DEBUG_MONITOR_H__
+
+#include <trap.h>
+
+void kmonitor(struct trapframe *tf);
+
+int mon_help(int argc, char **argv, struct trapframe *tf);
+int mon_kerninfo(int argc, char **argv, struct trapframe *tf);
+int mon_backtrace(int argc, char **argv, struct trapframe *tf);
+int mon_continue(int argc, char **argv, struct trapframe *tf);
+int mon_step(int argc, char **argv, struct trapframe *tf);
+int mon_breakpoint(int argc, char **argv, struct trapframe *tf);
+int mon_watchpoint(int argc, char **argv, struct trapframe *tf);
+int mon_delete_dr(int argc, char **argv, struct trapframe *tf);
+int mon_list_dr(int argc, char **argv, struct trapframe *tf);
+
+#endif /* !__KERN_DEBUG_MONITOR_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/panic.c b/related_info/lab5/lab5-spoc-discuss/kern/debug/panic.c
new file mode 100644
index 0000000..62d6189
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/panic.c
@@ -0,0 +1,49 @@
+#include <defs.h>
+#include <stdio.h>
+#include <intr.h>
+#include <kmonitor.h>
+
+static bool is_panic = 0;
+
+/* *
+ * __panic - __panic is called on unresolvable fatal errors. it prints
+ * "panic: 'message'", and then enters the kernel monitor.
+ * */
+void
+__panic(const char *file, int line, const char *fmt, ...) {
+    if (is_panic) {
+        goto panic_dead;
+    }
+    is_panic = 1;
+
+    // print the 'message'
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel panic at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+
+panic_dead:
+    intr_disable();
+    while (1) {
+        kmonitor(NULL);
+    }
+}
+
+/* __warn - like panic, but don't */
+void
+__warn(const char *file, int line, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel warning at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+}
+
+bool
+is_kernel_panic(void) {
+    return is_panic;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/debug/stab.h b/related_info/lab5/lab5-spoc-discuss/kern/debug/stab.h
new file mode 100644
index 0000000..8d5cea3
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/debug/stab.h
@@ -0,0 +1,54 @@
+#ifndef __KERN_DEBUG_STAB_H__
+#define __KERN_DEBUG_STAB_H__
+
+#include <defs.h>
+
+/* *
+ * STABS debugging info
+ *
+ * The kernel debugger can understand some debugging information in
+ * the STABS format.  For more information on this format, see
+ * http://sources.redhat.com/gdb/onlinedocs/stabs_toc.html
+ *
+ * The constants below define some symbol types used by various debuggers
+ * and compilers.  Kernel uses the N_SO, N_SOL, N_FUN, and N_SLINE types.
+ * */
+
+#define N_GSYM      0x20    // global symbol
+#define N_FNAME     0x22    // F77 function name
+#define N_FUN       0x24    // procedure name
+#define N_STSYM     0x26    // data segment variable
+#define N_LCSYM     0x28    // bss segment variable
+#define N_MAIN      0x2a    // main function name
+#define N_PC        0x30    // global Pascal symbol
+#define N_RSYM      0x40    // register variable
+#define N_SLINE     0x44    // text segment line number
+#define N_DSLINE    0x46    // data segment line number
+#define N_BSLINE    0x48    // bss segment line number
+#define N_SSYM      0x60    // structure/union element
+#define N_SO        0x64    // main source file name
+#define N_LSYM      0x80    // stack variable
+#define N_BINCL     0x82    // include file beginning
+#define N_SOL       0x84    // included source file name
+#define N_PSYM      0xa0    // parameter variable
+#define N_EINCL     0xa2    // include file end
+#define N_ENTRY     0xa4    // alternate entry point
+#define N_LBRAC     0xc0    // left bracket
+#define N_EXCL      0xc2    // deleted include file
+#define N_RBRAC     0xe0    // right bracket
+#define N_BCOMM     0xe2    // begin common
+#define N_ECOMM     0xe4    // end common
+#define N_ECOML     0xe8    // end common (local name)
+#define N_LENG      0xfe    // length of preceding entry
+
+/* Entries in the STABS table are formatted as follows. */
+struct stab {
+    uint32_t n_strx;        // index into string table of name
+    uint8_t n_type;         // type of symbol
+    uint8_t n_other;        // misc info (usually empty)
+    uint16_t n_desc;        // description field
+    uintptr_t n_value;      // value of symbol
+};
+
+#endif /* !__KERN_DEBUG_STAB_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.c b/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.c
new file mode 100644
index 0000000..4e67c3b
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.c
@@ -0,0 +1,45 @@
+#include <x86.h>
+#include <trap.h>
+#include <stdio.h>
+#include <picirq.h>
+
+/* *
+ * Support for time-related hardware gadgets - the 8253 timer,
+ * which generates interruptes on IRQ-0.
+ * */
+
+#define IO_TIMER1           0x040               // 8253 Timer #1
+
+/* *
+ * Frequency of all three count-down timers; (TIMER_FREQ/freq)
+ * is the appropriate count to generate a frequency of freq Hz.
+ * */
+
+#define TIMER_FREQ      1193182
+#define TIMER_DIV(x)    ((TIMER_FREQ + (x) / 2) / (x))
+
+#define TIMER_MODE      (IO_TIMER1 + 3)         // timer mode port
+#define TIMER_SEL0      0x00                    // select counter 0
+#define TIMER_RATEGEN   0x04                    // mode 2, rate generator
+#define TIMER_16BIT     0x30                    // r/w counter 16 bits, LSB first
+
+volatile size_t ticks;
+
+/* *
+ * clock_init - initialize 8253 clock to interrupt 100 times per second,
+ * and then enable IRQ_TIMER.
+ * */
+void
+clock_init(void) {
+    // set 8253 timer-chip
+    outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
+    outb(IO_TIMER1, TIMER_DIV(100) % 256);
+    outb(IO_TIMER1, TIMER_DIV(100) / 256);
+
+    // initialize time counter 'ticks' to zero
+    ticks = 0;
+
+    cprintf("++ setup timer interrupts\n");
+    pic_enable(IRQ_TIMER);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.h
new file mode 100644
index 0000000..e22f393
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/clock.h
@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CLOCK_H__
+#define __KERN_DRIVER_CLOCK_H__
+
+#include <defs.h>
+
+extern volatile size_t ticks;
+
+void clock_init(void);
+
+#endif /* !__KERN_DRIVER_CLOCK_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/console.c b/related_info/lab5/lab5-spoc-discuss/kern/driver/console.c
new file mode 100644
index 0000000..d4cf56b
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/console.c
@@ -0,0 +1,465 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <kbdreg.h>
+#include <picirq.h>
+#include <trap.h>
+#include <memlayout.h>
+#include <sync.h>
+
+/* stupid I/O delay routine necessitated by historical PC design flaws */
+static void
+delay(void) {
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+}
+
+/***** Serial I/O code *****/
+#define COM1            0x3F8
+
+#define COM_RX          0       // In:  Receive buffer (DLAB=0)
+#define COM_TX          0       // Out: Transmit buffer (DLAB=0)
+#define COM_DLL         0       // Out: Divisor Latch Low (DLAB=1)
+#define COM_DLM         1       // Out: Divisor Latch High (DLAB=1)
+#define COM_IER         1       // Out: Interrupt Enable Register
+#define COM_IER_RDI     0x01    // Enable receiver data interrupt
+#define COM_IIR         2       // In:  Interrupt ID Register
+#define COM_FCR         2       // Out: FIFO Control Register
+#define COM_LCR         3       // Out: Line Control Register
+#define COM_LCR_DLAB    0x80    // Divisor latch access bit
+#define COM_LCR_WLEN8   0x03    // Wordlength: 8 bits
+#define COM_MCR         4       // Out: Modem Control Register
+#define COM_MCR_RTS     0x02    // RTS complement
+#define COM_MCR_DTR     0x01    // DTR complement
+#define COM_MCR_OUT2    0x08    // Out2 complement
+#define COM_LSR         5       // In:  Line Status Register
+#define COM_LSR_DATA    0x01    // Data available
+#define COM_LSR_TXRDY   0x20    // Transmit buffer avail
+#define COM_LSR_TSRE    0x40    // Transmitter off
+
+#define MONO_BASE       0x3B4
+#define MONO_BUF        0xB0000
+#define CGA_BASE        0x3D4
+#define CGA_BUF         0xB8000
+#define CRT_ROWS        25
+#define CRT_COLS        80
+#define CRT_SIZE        (CRT_ROWS * CRT_COLS)
+
+#define LPTPORT         0x378
+
+static uint16_t *crt_buf;
+static uint16_t crt_pos;
+static uint16_t addr_6845;
+
+/* TEXT-mode CGA/VGA display output */
+
+static void
+cga_init(void) {
+    volatile uint16_t *cp = (uint16_t *)(CGA_BUF + KERNBASE);
+    uint16_t was = *cp;
+    *cp = (uint16_t) 0xA55A;
+    if (*cp != 0xA55A) {
+        cp = (uint16_t*)(MONO_BUF + KERNBASE);
+        addr_6845 = MONO_BASE;
+    } else {
+        *cp = was;
+        addr_6845 = CGA_BASE;
+    }
+
+    // Extract cursor location
+    uint32_t pos;
+    outb(addr_6845, 14);
+    pos = inb(addr_6845 + 1) << 8;
+    outb(addr_6845, 15);
+    pos |= inb(addr_6845 + 1);
+
+    crt_buf = (uint16_t*) cp;
+    crt_pos = pos;
+}
+
+static bool serial_exists = 0;
+
+static void
+serial_init(void) {
+    // Turn off the FIFO
+    outb(COM1 + COM_FCR, 0);
+
+    // Set speed; requires DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_DLAB);
+    outb(COM1 + COM_DLL, (uint8_t) (115200 / 9600));
+    outb(COM1 + COM_DLM, 0);
+
+    // 8 data bits, 1 stop bit, parity off; turn off DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_WLEN8 & ~COM_LCR_DLAB);
+
+    // No modem controls
+    outb(COM1 + COM_MCR, 0);
+    // Enable rcv interrupts
+    outb(COM1 + COM_IER, COM_IER_RDI);
+
+    // Clear any preexisting overrun indications and interrupts
+    // Serial port doesn't exist if COM_LSR returns 0xFF
+    serial_exists = (inb(COM1 + COM_LSR) != 0xFF);
+    (void) inb(COM1+COM_IIR);
+    (void) inb(COM1+COM_RX);
+
+    if (serial_exists) {
+        pic_enable(IRQ_COM1);
+    }
+}
+
+static void
+lpt_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(LPTPORT + 1) & 0x80) && i < 12800; i ++) {
+        delay();
+    }
+    outb(LPTPORT + 0, c);
+    outb(LPTPORT + 2, 0x08 | 0x04 | 0x01);
+    outb(LPTPORT + 2, 0x08);
+}
+
+/* lpt_putc - copy console output to parallel port */
+static void
+lpt_putc(int c) {
+    if (c != '\b') {
+        lpt_putc_sub(c);
+    }
+    else {
+        lpt_putc_sub('\b');
+        lpt_putc_sub(' ');
+        lpt_putc_sub('\b');
+    }
+}
+
+/* cga_putc - print character to console */
+static void
+cga_putc(int c) {
+    // set black on white
+    if (!(c & ~0xFF)) {
+        c |= 0x0700;
+    }
+
+    switch (c & 0xff) {
+    case '\b':
+        if (crt_pos > 0) {
+            crt_pos --;
+            crt_buf[crt_pos] = (c & ~0xff) | ' ';
+        }
+        break;
+    case '\n':
+        crt_pos += CRT_COLS;
+    case '\r':
+        crt_pos -= (crt_pos % CRT_COLS);
+        break;
+    default:
+        crt_buf[crt_pos ++] = c;     // write the character
+        break;
+    }
+
+    // What is the purpose of this?
+    if (crt_pos >= CRT_SIZE) {
+        int i;
+        memmove(crt_buf, crt_buf + CRT_COLS, (CRT_SIZE - CRT_COLS) * sizeof(uint16_t));
+        for (i = CRT_SIZE - CRT_COLS; i < CRT_SIZE; i ++) {
+            crt_buf[i] = 0x0700 | ' ';
+        }
+        crt_pos -= CRT_COLS;
+    }
+
+    // move that little blinky thing
+    outb(addr_6845, 14);
+    outb(addr_6845 + 1, crt_pos >> 8);
+    outb(addr_6845, 15);
+    outb(addr_6845 + 1, crt_pos);
+}
+
+static void
+serial_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(COM1 + COM_LSR) & COM_LSR_TXRDY) && i < 12800; i ++) {
+        delay();
+    }
+    outb(COM1 + COM_TX, c);
+}
+
+/* serial_putc - print character to serial port */
+static void
+serial_putc(int c) {
+    if (c != '\b') {
+        serial_putc_sub(c);
+    }
+    else {
+        serial_putc_sub('\b');
+        serial_putc_sub(' ');
+        serial_putc_sub('\b');
+    }
+}
+
+/* *
+ * Here we manage the console input buffer, where we stash characters
+ * received from the keyboard or serial port whenever the corresponding
+ * interrupt occurs.
+ * */
+
+#define CONSBUFSIZE 512
+
+static struct {
+    uint8_t buf[CONSBUFSIZE];
+    uint32_t rpos;
+    uint32_t wpos;
+} cons;
+
+/* *
+ * cons_intr - called by device interrupt routines to feed input
+ * characters into the circular console input buffer.
+ * */
+static void
+cons_intr(int (*proc)(void)) {
+    int c;
+    while ((c = (*proc)()) != -1) {
+        if (c != 0) {
+            cons.buf[cons.wpos ++] = c;
+            if (cons.wpos == CONSBUFSIZE) {
+                cons.wpos = 0;
+            }
+        }
+    }
+}
+
+/* serial_proc_data - get data from serial port */
+static int
+serial_proc_data(void) {
+    if (!(inb(COM1 + COM_LSR) & COM_LSR_DATA)) {
+        return -1;
+    }
+    int c = inb(COM1 + COM_RX);
+    if (c == 127) {
+        c = '\b';
+    }
+    return c;
+}
+
+/* serial_intr - try to feed input characters from serial port */
+void
+serial_intr(void) {
+    if (serial_exists) {
+        cons_intr(serial_proc_data);
+    }
+}
+
+/***** Keyboard input code *****/
+
+#define NO              0
+
+#define SHIFT           (1<<0)
+#define CTL             (1<<1)
+#define ALT             (1<<2)
+
+#define CAPSLOCK        (1<<3)
+#define NUMLOCK         (1<<4)
+#define SCROLLLOCK      (1<<5)
+
+#define E0ESC           (1<<6)
+
+static uint8_t shiftcode[256] = {
+    [0x1D] CTL,
+    [0x2A] SHIFT,
+    [0x36] SHIFT,
+    [0x38] ALT,
+    [0x9D] CTL,
+    [0xB8] ALT
+};
+
+static uint8_t togglecode[256] = {
+    [0x3A] CAPSLOCK,
+    [0x45] NUMLOCK,
+    [0x46] SCROLLLOCK
+};
+
+static uint8_t normalmap[256] = {
+    NO,   0x1B, '1',  '2',  '3',  '4',  '5',  '6',  // 0x00
+    '7',  '8',  '9',  '0',  '-',  '=',  '\b', '\t',
+    'q',  'w',  'e',  'r',  't',  'y',  'u',  'i',  // 0x10
+    'o',  'p',  '[',  ']',  '\n', NO,   'a',  's',
+    'd',  'f',  'g',  'h',  'j',  'k',  'l',  ';',  // 0x20
+    '\'', '`',  NO,   '\\', 'z',  'x',  'c',  'v',
+    'b',  'n',  'm',  ',',  '.',  '/',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t shiftmap[256] = {
+    NO,   033,  '!',  '@',  '#',  '$',  '%',  '^',  // 0x00
+    '&',  '*',  '(',  ')',  '_',  '+',  '\b', '\t',
+    'Q',  'W',  'E',  'R',  'T',  'Y',  'U',  'I',  // 0x10
+    'O',  'P',  '{',  '}',  '\n', NO,   'A',  'S',
+    'D',  'F',  'G',  'H',  'J',  'K',  'L',  ':',  // 0x20
+    '"',  '~',  NO,   '|',  'Z',  'X',  'C',  'V',
+    'B',  'N',  'M',  '<',  '>',  '?',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+#define C(x) (x - '@')
+
+static uint8_t ctlmap[256] = {
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    C('Q'),  C('W'),  C('E'),  C('R'),  C('T'),  C('Y'),  C('U'),  C('I'),
+    C('O'),  C('P'),  NO,      NO,      '\r',    NO,      C('A'),  C('S'),
+    C('D'),  C('F'),  C('G'),  C('H'),  C('J'),  C('K'),  C('L'),  NO,
+    NO,      NO,      NO,      C('\\'), C('Z'),  C('X'),  C('C'),  C('V'),
+    C('B'),  C('N'),  C('M'),  NO,      NO,      C('/'),  NO,      NO,
+    [0x97] KEY_HOME,
+    [0xB5] C('/'),      [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t *charcode[4] = {
+    normalmap,
+    shiftmap,
+    ctlmap,
+    ctlmap
+};
+
+/* *
+ * kbd_proc_data - get data from keyboard
+ *
+ * The kbd_proc_data() function gets data from the keyboard.
+ * If we finish a character, return it, else 0. And return -1 if no data.
+ * */
+static int
+kbd_proc_data(void) {
+    int c;
+    uint8_t data;
+    static uint32_t shift;
+
+    if ((inb(KBSTATP) & KBS_DIB) == 0) {
+        return -1;
+    }
+
+    data = inb(KBDATAP);
+
+    if (data == 0xE0) {
+        // E0 escape character
+        shift |= E0ESC;
+        return 0;
+    } else if (data & 0x80) {
+        // Key released
+        data = (shift & E0ESC ? data : data & 0x7F);
+        shift &= ~(shiftcode[data] | E0ESC);
+        return 0;
+    } else if (shift & E0ESC) {
+        // Last character was an E0 escape; or with 0x80
+        data |= 0x80;
+        shift &= ~E0ESC;
+    }
+
+    shift |= shiftcode[data];
+    shift ^= togglecode[data];
+
+    c = charcode[shift & (CTL | SHIFT)][data];
+    if (shift & CAPSLOCK) {
+        if ('a' <= c && c <= 'z')
+            c += 'A' - 'a';
+        else if ('A' <= c && c <= 'Z')
+            c += 'a' - 'A';
+    }
+
+    // Process special keys
+    // Ctrl-Alt-Del: reboot
+    if (!(~shift & (CTL | ALT)) && c == KEY_DEL) {
+        cprintf("Rebooting!\n");
+        outb(0x92, 0x3); // courtesy of Chris Frost
+    }
+    return c;
+}
+
+/* kbd_intr - try to feed input characters from keyboard */
+static void
+kbd_intr(void) {
+    cons_intr(kbd_proc_data);
+}
+
+static void
+kbd_init(void) {
+    // drain the kbd buffer
+    kbd_intr();
+    pic_enable(IRQ_KBD);
+}
+
+/* cons_init - initializes the console devices */
+void
+cons_init(void) {
+    cga_init();
+    serial_init();
+    kbd_init();
+    if (!serial_exists) {
+        cprintf("serial port does not exist!!\n");
+    }
+}
+
+/* cons_putc - print a single character @c to console devices */
+void
+cons_putc(int c) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        lpt_putc(c);
+        cga_putc(c);
+        serial_putc(c);
+    }
+    local_intr_restore(intr_flag);
+}
+
+/* *
+ * cons_getc - return the next input character from console,
+ * or 0 if none waiting.
+ * */
+int
+cons_getc(void) {
+    int c = 0;
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        // poll for any pending input characters,
+        // so that this function works even when interrupts are disabled
+        // (e.g., when called from the kernel monitor).
+        serial_intr();
+        kbd_intr();
+
+        // grab the next character from the input buffer.
+        if (cons.rpos != cons.wpos) {
+            c = cons.buf[cons.rpos ++];
+            if (cons.rpos == CONSBUFSIZE) {
+                cons.rpos = 0;
+            }
+        }
+    }
+    local_intr_restore(intr_flag);
+    return c;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/console.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/console.h
new file mode 100644
index 0000000..72e6167
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/console.h
@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CONSOLE_H__
+#define __KERN_DRIVER_CONSOLE_H__
+
+void cons_init(void);
+void cons_putc(int c);
+int cons_getc(void);
+void serial_intr(void);
+void kbd_intr(void);
+
+#endif /* !__KERN_DRIVER_CONSOLE_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.c b/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.c
new file mode 100644
index 0000000..271cfa8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.c
@@ -0,0 +1,214 @@
+#include <defs.h>
+#include <stdio.h>
+#include <trap.h>
+#include <picirq.h>
+#include <fs.h>
+#include <ide.h>
+#include <x86.h>
+#include <assert.h>
+
+#define ISA_DATA                0x00
+#define ISA_ERROR               0x01
+#define ISA_PRECOMP             0x01
+#define ISA_CTRL                0x02
+#define ISA_SECCNT              0x02
+#define ISA_SECTOR              0x03
+#define ISA_CYL_LO              0x04
+#define ISA_CYL_HI              0x05
+#define ISA_SDH                 0x06
+#define ISA_COMMAND             0x07
+#define ISA_STATUS              0x07
+
+#define IDE_BSY                 0x80
+#define IDE_DRDY                0x40
+#define IDE_DF                  0x20
+#define IDE_DRQ                 0x08
+#define IDE_ERR                 0x01
+
+#define IDE_CMD_READ            0x20
+#define IDE_CMD_WRITE           0x30
+#define IDE_CMD_IDENTIFY        0xEC
+
+#define IDE_IDENT_SECTORS       20
+#define IDE_IDENT_MODEL         54
+#define IDE_IDENT_CAPABILITIES  98
+#define IDE_IDENT_CMDSETS       164
+#define IDE_IDENT_MAX_LBA       120
+#define IDE_IDENT_MAX_LBA_EXT   200
+
+#define IO_BASE0                0x1F0
+#define IO_BASE1                0x170
+#define IO_CTRL0                0x3F4
+#define IO_CTRL1                0x374
+
+#define MAX_IDE                 4
+#define MAX_NSECS               128
+#define MAX_DISK_NSECS          0x10000000U
+#define VALID_IDE(ideno)        (((ideno) >= 0) && ((ideno) < MAX_IDE) && (ide_devices[ideno].valid))
+
+static const struct {
+    unsigned short base;        // I/O Base
+    unsigned short ctrl;        // Control Base
+} channels[2] = {
+    {IO_BASE0, IO_CTRL0},
+    {IO_BASE1, IO_CTRL1},
+};
+
+#define IO_BASE(ideno)          (channels[(ideno) >> 1].base)
+#define IO_CTRL(ideno)          (channels[(ideno) >> 1].ctrl)
+
+static struct ide_device {
+    unsigned char valid;        // 0 or 1 (If Device Really Exists)
+    unsigned int sets;          // Commend Sets Supported
+    unsigned int size;          // Size in Sectors
+    unsigned char model[41];    // Model in String
+} ide_devices[MAX_IDE];
+
+static int
+ide_wait_ready(unsigned short iobase, bool check_error) {
+    int r;
+    while ((r = inb(iobase + ISA_STATUS)) & IDE_BSY)
+        /* nothing */;
+    if (check_error && (r & (IDE_DF | IDE_ERR)) != 0) {
+        return -1;
+    }
+    return 0;
+}
+
+void
+ide_init(void) {
+    static_assert((SECTSIZE % 4) == 0);
+    unsigned short ideno, iobase;
+    for (ideno = 0; ideno < MAX_IDE; ideno ++) {
+        /* assume that no device here */
+        ide_devices[ideno].valid = 0;
+
+        iobase = IO_BASE(ideno);
+
+        /* wait device ready */
+        ide_wait_ready(iobase, 0);
+
+        /* step1: select drive */
+        outb(iobase + ISA_SDH, 0xE0 | ((ideno & 1) << 4));
+        ide_wait_ready(iobase, 0);
+
+        /* step2: send ATA identify command */
+        outb(iobase + ISA_COMMAND, IDE_CMD_IDENTIFY);
+        ide_wait_ready(iobase, 0);
+
+        /* step3: polling */
+        if (inb(iobase + ISA_STATUS) == 0 || ide_wait_ready(iobase, 1) != 0) {
+            continue ;
+        }
+
+        /* device is ok */
+        ide_devices[ideno].valid = 1;
+
+        /* read identification space of the device */
+        unsigned int buffer[128];
+        insl(iobase + ISA_DATA, buffer, sizeof(buffer) / sizeof(unsigned int));
+
+        unsigned char *ident = (unsigned char *)buffer;
+        unsigned int sectors;
+        unsigned int cmdsets = *(unsigned int *)(ident + IDE_IDENT_CMDSETS);
+        /* device use 48-bits or 28-bits addressing */
+        if (cmdsets & (1 << 26)) {
+            sectors = *(unsigned int *)(ident + IDE_IDENT_MAX_LBA_EXT);
+        }
+        else {
+            sectors = *(unsigned int *)(ident + IDE_IDENT_MAX_LBA);
+        }
+        ide_devices[ideno].sets = cmdsets;
+        ide_devices[ideno].size = sectors;
+
+        /* check if supports LBA */
+        assert((*(unsigned short *)(ident + IDE_IDENT_CAPABILITIES) & 0x200) != 0);
+
+        unsigned char *model = ide_devices[ideno].model, *data = ident + IDE_IDENT_MODEL;
+        unsigned int i, length = 40;
+        for (i = 0; i < length; i += 2) {
+            model[i] = data[i + 1], model[i + 1] = data[i];
+        }
+        do {
+            model[i] = '\0';
+        } while (i -- > 0 && model[i] == ' ');
+
+        cprintf("ide %d: %10u(sectors), '%s'.\n", ideno, ide_devices[ideno].size, ide_devices[ideno].model);
+    }
+
+    // enable ide interrupt
+    pic_enable(IRQ_IDE1);
+    pic_enable(IRQ_IDE2);
+}
+
+bool
+ide_device_valid(unsigned short ideno) {
+    return VALID_IDE(ideno);
+}
+
+size_t
+ide_device_size(unsigned short ideno) {
+    if (ide_device_valid(ideno)) {
+        return ide_devices[ideno].size;
+    }
+    return 0;
+}
+
+int
+ide_read_secs(unsigned short ideno, uint32_t secno, void *dst, size_t nsecs) {
+    assert(nsecs <= MAX_NSECS && VALID_IDE(ideno));
+    assert(secno < MAX_DISK_NSECS && secno + nsecs <= MAX_DISK_NSECS);
+    unsigned short iobase = IO_BASE(ideno), ioctrl = IO_CTRL(ideno);
+
+    ide_wait_ready(iobase, 0);
+
+    // generate interrupt
+    outb(ioctrl + ISA_CTRL, 0);
+    outb(iobase + ISA_SECCNT, nsecs);
+    outb(iobase + ISA_SECTOR, secno & 0xFF);
+    outb(iobase + ISA_CYL_LO, (secno >> 8) & 0xFF);
+    outb(iobase + ISA_CYL_HI, (secno >> 16) & 0xFF);
+    outb(iobase + ISA_SDH, 0xE0 | ((ideno & 1) << 4) | ((secno >> 24) & 0xF));
+    outb(iobase + ISA_COMMAND, IDE_CMD_READ);
+
+    int ret = 0;
+    for (; nsecs > 0; nsecs --, dst += SECTSIZE) {
+        if ((ret = ide_wait_ready(iobase, 1)) != 0) {
+            goto out;
+        }
+        insl(iobase, dst, SECTSIZE / sizeof(uint32_t));
+    }
+
+out:
+    return ret;
+}
+
+int
+ide_write_secs(unsigned short ideno, uint32_t secno, const void *src, size_t nsecs) {
+    assert(nsecs <= MAX_NSECS && VALID_IDE(ideno));
+    assert(secno < MAX_DISK_NSECS && secno + nsecs <= MAX_DISK_NSECS);
+    unsigned short iobase = IO_BASE(ideno), ioctrl = IO_CTRL(ideno);
+
+    ide_wait_ready(iobase, 0);
+
+    // generate interrupt
+    outb(ioctrl + ISA_CTRL, 0);
+    outb(iobase + ISA_SECCNT, nsecs);
+    outb(iobase + ISA_SECTOR, secno & 0xFF);
+    outb(iobase + ISA_CYL_LO, (secno >> 8) & 0xFF);
+    outb(iobase + ISA_CYL_HI, (secno >> 16) & 0xFF);
+    outb(iobase + ISA_SDH, 0xE0 | ((ideno & 1) << 4) | ((secno >> 24) & 0xF));
+    outb(iobase + ISA_COMMAND, IDE_CMD_WRITE);
+
+    int ret = 0;
+    for (; nsecs > 0; nsecs --, src += SECTSIZE) {
+        if ((ret = ide_wait_ready(iobase, 1)) != 0) {
+            goto out;
+        }
+        outsl(iobase, src, SECTSIZE / sizeof(uint32_t));
+    }
+
+out:
+    return ret;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.h
new file mode 100644
index 0000000..3e3fd21
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/ide.h
@@ -0,0 +1,14 @@
+#ifndef __KERN_DRIVER_IDE_H__
+#define __KERN_DRIVER_IDE_H__
+
+#include <defs.h>
+
+void ide_init(void);
+bool ide_device_valid(unsigned short ideno);
+size_t ide_device_size(unsigned short ideno);
+
+int ide_read_secs(unsigned short ideno, uint32_t secno, void *dst, size_t nsecs);
+int ide_write_secs(unsigned short ideno, uint32_t secno, const void *src, size_t nsecs);
+
+#endif /* !__KERN_DRIVER_IDE_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.c b/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.c
new file mode 100644
index 0000000..e64da62
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.c
@@ -0,0 +1,15 @@
+#include <x86.h>
+#include <intr.h>
+
+/* intr_enable - enable irq interrupt */
+void
+intr_enable(void) {
+    sti();
+}
+
+/* intr_disable - disable irq interrupt */
+void
+intr_disable(void) {
+    cli();
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.h
new file mode 100644
index 0000000..5fdf7a5
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/intr.h
@@ -0,0 +1,8 @@
+#ifndef __KERN_DRIVER_INTR_H__
+#define __KERN_DRIVER_INTR_H__
+
+void intr_enable(void);
+void intr_disable(void);
+
+#endif /* !__KERN_DRIVER_INTR_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/kbdreg.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/kbdreg.h
new file mode 100644
index 0000000..00dc49a
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/kbdreg.h
@@ -0,0 +1,84 @@
+#ifndef __KERN_DRIVER_KBDREG_H__
+#define __KERN_DRIVER_KBDREG_H__
+
+// Special keycodes
+#define KEY_HOME            0xE0
+#define KEY_END             0xE1
+#define KEY_UP              0xE2
+#define KEY_DN              0xE3
+#define KEY_LF              0xE4
+#define KEY_RT              0xE5
+#define KEY_PGUP            0xE6
+#define KEY_PGDN            0xE7
+#define KEY_INS             0xE8
+#define KEY_DEL             0xE9
+
+
+/* This is i8042reg.h + kbdreg.h from NetBSD. */
+
+#define KBSTATP             0x64    // kbd controller status port(I)
+#define KBS_DIB             0x01    // kbd data in buffer
+#define KBS_IBF             0x02    // kbd input buffer low
+#define KBS_WARM            0x04    // kbd input buffer low
+#define BS_OCMD             0x08    // kbd output buffer has command
+#define KBS_NOSEC           0x10    // kbd security lock not engaged
+#define KBS_TERR            0x20    // kbd transmission error
+#define KBS_RERR            0x40    // kbd receive error
+#define KBS_PERR            0x80    // kbd parity error
+
+#define KBCMDP              0x64    // kbd controller port(O)
+#define KBC_RAMREAD         0x20    // read from RAM
+#define KBC_RAMWRITE        0x60    // write to RAM
+#define KBC_AUXDISABLE      0xa7    // disable auxiliary port
+#define KBC_AUXENABLE       0xa8    // enable auxiliary port
+#define KBC_AUXTEST         0xa9    // test auxiliary port
+#define KBC_KBDECHO         0xd2    // echo to keyboard port
+#define KBC_AUXECHO         0xd3    // echo to auxiliary port
+#define KBC_AUXWRITE        0xd4    // write to auxiliary port
+#define KBC_SELFTEST        0xaa    // start self-test
+#define KBC_KBDTEST         0xab    // test keyboard port
+#define KBC_KBDDISABLE      0xad    // disable keyboard port
+#define KBC_KBDENABLE       0xae    // enable keyboard port
+#define KBC_PULSE0          0xfe    // pulse output bit 0
+#define KBC_PULSE1          0xfd    // pulse output bit 1
+#define KBC_PULSE2          0xfb    // pulse output bit 2
+#define KBC_PULSE3          0xf7    // pulse output bit 3
+
+#define KBDATAP             0x60    // kbd data port(I)
+#define KBOUTP              0x60    // kbd data port(O)
+
+#define K_RDCMDBYTE         0x20
+#define K_LDCMDBYTE         0x60
+
+#define KC8_TRANS           0x40    // convert to old scan codes
+#define KC8_MDISABLE        0x20    // disable mouse
+#define KC8_KDISABLE        0x10    // disable keyboard
+#define KC8_IGNSEC          0x08    // ignore security lock
+#define KC8_CPU             0x04    // exit from protected mode reset
+#define KC8_MENABLE         0x02    // enable mouse interrupt
+#define KC8_KENABLE         0x01    // enable keyboard interrupt
+#define CMDBYTE             (KC8_TRANS|KC8_CPU|KC8_MENABLE|KC8_KENABLE)
+
+/* keyboard commands */
+#define KBC_RESET           0xFF    // reset the keyboard
+#define KBC_RESEND          0xFE    // request the keyboard resend the last byte
+#define KBC_SETDEFAULT      0xF6    // resets keyboard to its power-on defaults
+#define KBC_DISABLE         0xF5    // as per KBC_SETDEFAULT, but also disable key scanning
+#define KBC_ENABLE          0xF4    // enable key scanning
+#define KBC_TYPEMATIC       0xF3    // set typematic rate and delay
+#define KBC_SETTABLE        0xF0    // set scancode translation table
+#define KBC_MODEIND         0xED    // set mode indicators(i.e. LEDs)
+#define KBC_ECHO            0xEE    // request an echo from the keyboard
+
+/* keyboard responses */
+#define KBR_EXTENDED        0xE0    // extended key sequence
+#define KBR_RESEND          0xFE    // needs resend of command
+#define KBR_ACK             0xFA    // received a valid command
+#define KBR_OVERRUN         0x00    // flooded
+#define KBR_FAILURE         0xFD    // diagnosic failure
+#define KBR_BREAK           0xF0    // break code prefix - sent on key release
+#define KBR_RSTDONE         0xAA    // reset complete
+#define KBR_ECHO            0xEE    // echo response
+
+#endif /* !__KERN_DRIVER_KBDREG_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.c b/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.c
new file mode 100644
index 0000000..e7f7063
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.c
@@ -0,0 +1,86 @@
+#include <defs.h>
+#include <x86.h>
+#include <picirq.h>
+
+// I/O Addresses of the two programmable interrupt controllers
+#define IO_PIC1             0x20    // Master (IRQs 0-7)
+#define IO_PIC2             0xA0    // Slave (IRQs 8-15)
+
+#define IRQ_SLAVE           2       // IRQ at which slave connects to master
+
+// Current IRQ mask.
+// Initial IRQ mask has interrupt 2 enabled (for slave 8259A).
+static uint16_t irq_mask = 0xFFFF & ~(1 << IRQ_SLAVE);
+static bool did_init = 0;
+
+static void
+pic_setmask(uint16_t mask) {
+    irq_mask = mask;
+    if (did_init) {
+        outb(IO_PIC1 + 1, mask);
+        outb(IO_PIC2 + 1, mask >> 8);
+    }
+}
+
+void
+pic_enable(unsigned int irq) {
+    pic_setmask(irq_mask & ~(1 << irq));
+}
+
+/* pic_init - initialize the 8259A interrupt controllers */
+void
+pic_init(void) {
+    did_init = 1;
+
+    // mask all interrupts
+    outb(IO_PIC1 + 1, 0xFF);
+    outb(IO_PIC2 + 1, 0xFF);
+
+    // Set up master (8259A-1)
+
+    // ICW1:  0001g0hi
+    //    g:  0 = edge triggering, 1 = level triggering
+    //    h:  0 = cascaded PICs, 1 = master only
+    //    i:  0 = no ICW4, 1 = ICW4 required
+    outb(IO_PIC1, 0x11);
+
+    // ICW2:  Vector offset
+    outb(IO_PIC1 + 1, IRQ_OFFSET);
+
+    // ICW3:  (master PIC) bit mask of IR lines connected to slaves
+    //        (slave PIC) 3-bit # of slave's connection to master
+    outb(IO_PIC1 + 1, 1 << IRQ_SLAVE);
+
+    // ICW4:  000nbmap
+    //    n:  1 = special fully nested mode
+    //    b:  1 = buffered mode
+    //    m:  0 = slave PIC, 1 = master PIC
+    //        (ignored when b is 0, as the master/slave role
+    //         can be hardwired).
+    //    a:  1 = Automatic EOI mode
+    //    p:  0 = MCS-80/85 mode, 1 = intel x86 mode
+    outb(IO_PIC1 + 1, 0x3);
+
+    // Set up slave (8259A-2)
+    outb(IO_PIC2, 0x11);    // ICW1
+    outb(IO_PIC2 + 1, IRQ_OFFSET + 8);  // ICW2
+    outb(IO_PIC2 + 1, IRQ_SLAVE);       // ICW3
+    // NB Automatic EOI mode doesn't tend to work on the slave.
+    // Linux source code says it's "to be investigated".
+    outb(IO_PIC2 + 1, 0x3);             // ICW4
+
+    // OCW3:  0ef01prs
+    //   ef:  0x = NOP, 10 = clear specific mask, 11 = set specific mask
+    //    p:  0 = no polling, 1 = polling mode
+    //   rs:  0x = NOP, 10 = read IRR, 11 = read ISR
+    outb(IO_PIC1, 0x68);    // clear specific mask
+    outb(IO_PIC1, 0x0a);    // read IRR by default
+
+    outb(IO_PIC2, 0x68);    // OCW3
+    outb(IO_PIC2, 0x0a);    // OCW3
+
+    if (irq_mask != 0xFFFF) {
+        pic_setmask(irq_mask);
+    }
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.h b/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.h
new file mode 100644
index 0000000..b61e72e
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/driver/picirq.h
@@ -0,0 +1,10 @@
+#ifndef __KERN_DRIVER_PICIRQ_H__
+#define __KERN_DRIVER_PICIRQ_H__
+
+void pic_init(void);
+void pic_enable(unsigned int irq);
+
+#define IRQ_OFFSET      32
+
+#endif /* !__KERN_DRIVER_PICIRQ_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/fs/fs.h b/related_info/lab5/lab5-spoc-discuss/kern/fs/fs.h
new file mode 100644
index 0000000..92c05e7
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/fs/fs.h
@@ -0,0 +1,12 @@
+#ifndef __KERN_FS_FS_H__
+#define __KERN_FS_FS_H__
+
+#include <mmu.h>
+
+#define SECTSIZE            512
+#define PAGE_NSECT          (PGSIZE / SECTSIZE)
+
+#define SWAP_DEV_NO         1
+
+#endif /* !__KERN_FS_FS_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.c b/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.c
new file mode 100644
index 0000000..d9f6090
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.c
@@ -0,0 +1,27 @@
+#include <swap.h>
+#include <swapfs.h>
+#include <mmu.h>
+#include <fs.h>
+#include <ide.h>
+#include <pmm.h>
+#include <assert.h>
+
+void
+swapfs_init(void) {
+    static_assert((PGSIZE % SECTSIZE) == 0);
+    if (!ide_device_valid(SWAP_DEV_NO)) {
+        panic("swap fs isn't available.\n");
+    }
+    max_swap_offset = ide_device_size(SWAP_DEV_NO) / (PGSIZE / SECTSIZE);
+}
+
+int
+swapfs_read(swap_entry_t entry, struct Page *page) {
+    return ide_read_secs(SWAP_DEV_NO, swap_offset(entry) * PAGE_NSECT, page2kva(page), PAGE_NSECT);
+}
+
+int
+swapfs_write(swap_entry_t entry, struct Page *page) {
+    return ide_write_secs(SWAP_DEV_NO, swap_offset(entry) * PAGE_NSECT, page2kva(page), PAGE_NSECT);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.h b/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.h
new file mode 100644
index 0000000..d433926
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/fs/swapfs.h
@@ -0,0 +1,12 @@
+#ifndef __KERN_FS_SWAPFS_H__
+#define __KERN_FS_SWAPFS_H__
+
+#include <memlayout.h>
+#include <swap.h>
+
+void swapfs_init(void);
+int swapfs_read(swap_entry_t entry, struct Page *page);
+int swapfs_write(swap_entry_t entry, struct Page *page);
+
+#endif /* !__KERN_FS_SWAPFS_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/init/entry.S b/related_info/lab5/lab5-spoc-discuss/kern/init/entry.S
new file mode 100644
index 0000000..8e37f2a
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/init/entry.S
@@ -0,0 +1,49 @@
+#include <mmu.h>
+#include <memlayout.h>
+
+#define REALLOC(x) (x - KERNBASE)
+
+.text
+.globl kern_entry
+kern_entry:
+    # reload temperate gdt (second time) to remap all physical memory
+    # virtual_addr 0~4G=linear_addr&physical_addr -KERNBASE~4G-KERNBASE 
+    lgdt REALLOC(__gdtdesc)
+    movl $KERNEL_DS, %eax
+    movw %ax, %ds
+    movw %ax, %es
+    movw %ax, %ss
+
+    ljmp $KERNEL_CS, $relocated
+
+relocated:
+
+    # set ebp, esp
+    movl $0x0, %ebp
+    # the kernel stack region is from bootstack -- bootstacktop,
+    # the kernel stack size is KSTACKSIZE (8KB)defined in memlayout.h
+    movl $bootstacktop, %esp
+    # now kernel stack is ready , call the first C function
+    call kern_init
+
+# should never get here
+spin:
+    jmp spin
+
+.data
+.align PGSIZE
+    .globl bootstack
+bootstack:
+    .space KSTACKSIZE
+    .globl bootstacktop
+bootstacktop:
+
+.align 4
+__gdt:
+    SEG_NULL
+    SEG_ASM(STA_X | STA_R, - KERNBASE, 0xFFFFFFFF)      # code segment
+    SEG_ASM(STA_W, - KERNBASE, 0xFFFFFFFF)              # data segment
+__gdtdesc:
+    .word 0x17                                          # sizeof(__gdt) - 1
+    .long REALLOC(__gdt)
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/init/init.c b/related_info/lab5/lab5-spoc-discuss/kern/init/init.c
new file mode 100644
index 0000000..5546347
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/init/init.c
@@ -0,0 +1,113 @@
+#include <defs.h>
+#include <stdio.h>
+#include <string.h>
+#include <console.h>
+#include <kdebug.h>
+#include <picirq.h>
+#include <trap.h>
+#include <clock.h>
+#include <intr.h>
+#include <pmm.h>
+#include <vmm.h>
+#include <ide.h>
+#include <swap.h>
+#include <proc.h>
+
+int kern_init(void) __attribute__((noreturn));
+
+static void lab1_switch_test(void);
+
+int
+kern_init(void) {
+    extern char edata[], end[];
+    memset(edata, 0, end - edata);
+
+    cons_init();                // init the console
+
+    const char *message = "(THU.CST) os is loading ...";
+    cprintf("%s\n\n", message);
+
+    print_kerninfo();
+
+    grade_backtrace();
+
+    pmm_init();                 // init physical memory management
+
+    pic_init();                 // init interrupt controller
+    idt_init();                 // init interrupt descriptor table
+
+    vmm_init();                 // init virtual memory management
+    proc_init();                // init process table
+    
+    ide_init();                 // init ide devices
+    swap_init();                // init swap
+
+    clock_init();               // init clock interrupt
+    intr_enable();              // enable irq interrupt
+
+    //LAB1: CAHLLENGE 1 If you try to do it, uncomment lab1_switch_test()
+    // user/kernel mode switch test
+    //lab1_switch_test();
+    
+    cpu_idle();                 // run idle process
+}
+
+void __attribute__((noinline))
+grade_backtrace2(int arg0, int arg1, int arg2, int arg3) {
+    mon_backtrace(0, NULL, NULL);
+}
+
+void __attribute__((noinline))
+grade_backtrace1(int arg0, int arg1) {
+    grade_backtrace2(arg0, (int)&arg0, arg1, (int)&arg1);
+}
+
+void __attribute__((noinline))
+grade_backtrace0(int arg0, int arg1, int arg2) {
+    grade_backtrace1(arg0, arg2);
+}
+
+void
+grade_backtrace(void) {
+    grade_backtrace0(0, (int)kern_init, 0xffff0000);
+}
+
+static void
+lab1_print_cur_status(void) {
+    static int round = 0;
+    uint16_t reg1, reg2, reg3, reg4;
+    asm volatile (
+            "mov %%cs, %0;"
+            "mov %%ds, %1;"
+            "mov %%es, %2;"
+            "mov %%ss, %3;"
+            : "=m"(reg1), "=m"(reg2), "=m"(reg3), "=m"(reg4));
+    cprintf("%d: @ring %d\n", round, reg1 & 3);
+    cprintf("%d:  cs = %x\n", round, reg1);
+    cprintf("%d:  ds = %x\n", round, reg2);
+    cprintf("%d:  es = %x\n", round, reg3);
+    cprintf("%d:  ss = %x\n", round, reg4);
+    round ++;
+}
+
+static void
+lab1_switch_to_user(void) {
+    //LAB1 CHALLENGE 1 : TODO
+}
+
+static void
+lab1_switch_to_kernel(void) {
+    //LAB1 CHALLENGE 1 :  TODO
+}
+
+static void
+lab1_switch_test(void) {
+    lab1_print_cur_status();
+    cprintf("+++ switch to  user  mode +++\n");
+    lab1_switch_to_user();
+    lab1_print_cur_status();
+    cprintf("+++ switch to kernel mode +++\n");
+    lab1_switch_to_kernel();
+    lab1_print_cur_status();
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.c b/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.c
new file mode 100644
index 0000000..0a5fcc8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.c
@@ -0,0 +1,528 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <kmalloc.h>
+#include <rb_tree.h>
+#include <assert.h>
+
+/* rb_node_create - create a new rb_node */
+static inline rb_node *
+rb_node_create(void) {
+    return kmalloc(sizeof(rb_node));
+}
+
+/* rb_tree_empty - tests if tree is empty */
+static inline bool
+rb_tree_empty(rb_tree *tree) {
+    rb_node *nil = tree->nil, *root = tree->root;
+    return root->left == nil;
+}
+
+/* *
+ * rb_tree_create - creates a new red-black tree, the 'compare' function
+ * is required and returns 'NULL' if failed.
+ *
+ * Note that, root->left should always point to the node that is the root
+ * of the tree. And nil points to a 'NULL' node which should always be
+ * black and may have arbitrary children and parent node.
+ * */
+rb_tree *
+rb_tree_create(int (*compare)(rb_node *node1, rb_node *node2)) {
+    assert(compare != NULL);
+
+    rb_tree *tree;
+    rb_node *nil, *root;
+
+    if ((tree = kmalloc(sizeof(rb_tree))) == NULL) {
+        goto bad_tree;
+    }
+
+    tree->compare = compare;
+
+    if ((nil = rb_node_create()) == NULL) {
+        goto bad_node_cleanup_tree;
+    }
+
+    nil->parent = nil->left = nil->right = nil;
+    nil->red = 0;
+    tree->nil = nil;
+
+    if ((root = rb_node_create()) == NULL) {
+        goto bad_node_cleanup_nil;
+    }
+
+    root->parent = root->left = root->right = nil;
+    root->red = 0;
+    tree->root = root;
+    return tree;
+
+bad_node_cleanup_nil:
+    kfree(nil);
+bad_node_cleanup_tree:
+    kfree(tree);
+bad_tree:
+    return NULL;
+}
+
+/* *
+ * FUNC_ROTATE - rotates as described in "Introduction to Algorithm".
+ *
+ * For example, FUNC_ROTATE(rb_left_rotate, left, right) can be expaned to a
+ * left-rotate function, which requires an red-black 'tree' and a node 'x'
+ * to be rotated on. Basically, this function, named rb_left_rotate, makes the
+ * parent of 'x' be the left child of 'x', 'x' the parent of its parent before
+ * rotation and finally fixes other nodes accordingly.
+ *
+ * FUNC_ROTATE(xx, left, right) means left-rotate,
+ * and FUNC_ROTATE(xx, right, left) means right-rotate.
+ * */
+#define FUNC_ROTATE(func_name, _left, _right)                   \
+static void                                                     \
+func_name(rb_tree *tree, rb_node *x) {                          \
+    rb_node *nil = tree->nil, *y = x->_right;                   \
+    assert(x != tree->root && x != nil && y != nil);            \
+    x->_right = y->_left;                                       \
+    if (y->_left != nil) {                                      \
+        y->_left->parent = x;                                   \
+    }                                                           \
+    y->parent = x->parent;                                      \
+    if (x == x->parent->_left) {                                \
+        x->parent->_left = y;                                   \
+    }                                                           \
+    else {                                                      \
+        x->parent->_right = y;                                  \
+    }                                                           \
+    y->_left = x;                                               \
+    x->parent = y;                                              \
+    assert(!(nil->red));                                        \
+}
+
+FUNC_ROTATE(rb_left_rotate, left, right);
+FUNC_ROTATE(rb_right_rotate, right, left);
+
+#undef FUNC_ROTATE
+
+#define COMPARE(tree, node1, node2)                             \
+    ((tree))->compare((node1), (node2))
+
+/* *
+ * rb_insert_binary - insert @node to red-black @tree as if it were
+ * a regular binary tree. This function is only intended to be called
+ * by function rb_insert.
+ * */
+static inline void
+rb_insert_binary(rb_tree *tree, rb_node *node) {
+    rb_node *x, *y, *z = node, *nil = tree->nil, *root = tree->root;
+
+    z->left = z->right = nil;
+    y = root, x = y->left;
+    while (x != nil) {
+        y = x;
+        x = (COMPARE(tree, x, node) > 0) ? x->left : x->right;
+    }
+    z->parent = y;
+    if (y == root || COMPARE(tree, y, z) > 0) {
+        y->left = z;
+    }
+    else {
+        y->right = z;
+    }
+}
+
+/* rb_insert - insert a node to red-black tree */
+void
+rb_insert(rb_tree *tree, rb_node *node) {
+    rb_insert_binary(tree, node);
+    node->red = 1;
+
+    rb_node *x = node, *y;
+
+#define RB_INSERT_SUB(_left, _right)                            \
+    do {                                                        \
+        y = x->parent->parent->_right;                          \
+        if (y->red) {                                           \
+            x->parent->red = 0;                                 \
+            y->red = 0;                                         \
+            x->parent->parent->red = 1;                         \
+            x = x->parent->parent;                              \
+        }                                                       \
+        else {                                                  \
+            if (x == x->parent->_right) {                       \
+                x = x->parent;                                  \
+                rb_##_left##_rotate(tree, x);                   \
+            }                                                   \
+            x->parent->red = 0;                                 \
+            x->parent->parent->red = 1;                         \
+            rb_##_right##_rotate(tree, x->parent->parent);      \
+        }                                                       \
+    } while (0)
+
+    while (x->parent->red) {
+        if (x->parent == x->parent->parent->left) {
+            RB_INSERT_SUB(left, right);
+        }
+        else {
+            RB_INSERT_SUB(right, left);
+        }
+    }
+    tree->root->left->red = 0;
+    assert(!(tree->nil->red) && !(tree->root->red));
+
+#undef RB_INSERT_SUB
+}
+
+/* *
+ * rb_tree_successor - returns the successor of @node, or nil
+ * if no successor exists. Make sure that @node must belong to @tree,
+ * and this function should only be called by rb_node_prev.
+ * */
+static inline rb_node *
+rb_tree_successor(rb_tree *tree, rb_node *node) {
+    rb_node *x = node, *y, *nil = tree->nil;
+
+    if ((y = x->right) != nil) {
+        while (y->left != nil) {
+            y = y->left;
+        }
+        return y;
+    }
+    else {
+        y = x->parent;
+        while (x == y->right) {
+            x = y, y = y->parent;
+        }
+        if (y == tree->root) {
+            return nil;
+        }
+        return y;
+    }
+}
+
+/* *
+ * rb_tree_predecessor - returns the predecessor of @node, or nil
+ * if no predecessor exists, likes rb_tree_successor.
+ * */
+static inline rb_node *
+rb_tree_predecessor(rb_tree *tree, rb_node *node) {
+    rb_node *x = node, *y, *nil = tree->nil;
+
+    if ((y = x->left) != nil) {
+        while (y->right != nil) {
+            y = y->right;
+        }
+        return y;
+    }
+    else {
+        y = x->parent;
+        while (x == y->left) {
+            if (y == tree->root) {
+                return nil;
+            }
+            x = y, y = y->parent;
+        }
+        return y;
+    }
+}
+
+/* *
+ * rb_search - returns a node with value 'equal' to @key (according to
+ * function @compare). If there're multiple nodes with value 'equal' to @key,
+ * the functions returns the one highest in the tree.
+ * */
+rb_node *
+rb_search(rb_tree *tree, int (*compare)(rb_node *node, void *key), void *key) {
+    rb_node *nil = tree->nil, *node = tree->root->left;
+    int r;
+    while (node != nil && (r = compare(node, key)) != 0) {
+        node = (r > 0) ? node->left : node->right;
+    }
+    return (node != nil) ? node : NULL;
+}
+
+/* *
+ * rb_delete_fixup - performs rotations and changes colors to restore
+ * red-black properties after a node is deleted.
+ * */
+static void
+rb_delete_fixup(rb_tree *tree, rb_node *node) {
+    rb_node *x = node, *w, *root = tree->root->left;
+
+#define RB_DELETE_FIXUP_SUB(_left, _right)                      \
+    do {                                                        \
+        w = x->parent->_right;                                  \
+        if (w->red) {                                           \
+            w->red = 0;                                         \
+            x->parent->red = 1;                                 \
+            rb_##_left##_rotate(tree, x->parent);               \
+            w = x->parent->_right;                              \
+        }                                                       \
+        if (!w->_left->red && !w->_right->red) {                \
+            w->red = 1;                                         \
+            x = x->parent;                                      \
+        }                                                       \
+        else {                                                  \
+            if (!w->_right->red) {                              \
+                w->_left->red = 0;                              \
+                w->red = 1;                                     \
+                rb_##_right##_rotate(tree, w);                  \
+                w = x->parent->_right;                          \
+            }                                                   \
+            w->red = x->parent->red;                            \
+            x->parent->red = 0;                                 \
+            w->_right->red = 0;                                 \
+            rb_##_left##_rotate(tree, x->parent);               \
+            x = root;                                           \
+        }                                                       \
+    } while (0)
+
+    while (x != root && !x->red) {
+        if (x == x->parent->left) {
+            RB_DELETE_FIXUP_SUB(left, right);
+        }
+        else {
+            RB_DELETE_FIXUP_SUB(right, left);
+        }
+    }
+    x->red = 0;
+
+#undef RB_DELETE_FIXUP_SUB
+}
+
+/* *
+ * rb_delete - deletes @node from @tree, and calls rb_delete_fixup to
+ * restore red-black properties.
+ * */
+void
+rb_delete(rb_tree *tree, rb_node *node) {
+    rb_node *x, *y, *z = node;
+    rb_node *nil = tree->nil, *root = tree->root;
+
+    y = (z->left == nil || z->right == nil) ? z : rb_tree_successor(tree, z);
+    x = (y->left != nil) ? y->left : y->right;
+
+    assert(y != root && y != nil);
+
+    x->parent = y->parent;
+    if (y == y->parent->left) {
+        y->parent->left = x;
+    }
+    else {
+        y->parent->right = x;
+    }
+
+    bool need_fixup = !(y->red);
+
+    if (y != z) {
+        if (z == z->parent->left) {
+            z->parent->left = y;
+        }
+        else {
+            z->parent->right = y;
+        }
+        z->left->parent = z->right->parent = y;
+        *y = *z;
+    }
+    if (need_fixup) {
+        rb_delete_fixup(tree, x);
+    }
+}
+
+/* rb_tree_destroy - destroy a tree and free memory */
+void
+rb_tree_destroy(rb_tree *tree) {
+    kfree(tree->root);
+    kfree(tree->nil);
+    kfree(tree);
+}
+
+/* *
+ * rb_node_prev - returns the predecessor node of @node in @tree,
+ * or 'NULL' if no predecessor exists.
+ * */
+rb_node *
+rb_node_prev(rb_tree *tree, rb_node *node) {
+    rb_node *prev = rb_tree_predecessor(tree, node);
+    return (prev != tree->nil) ? prev : NULL;
+}
+
+/* *
+ * rb_node_next - returns the successor node of @node in @tree,
+ * or 'NULL' if no successor exists.
+ * */
+rb_node *
+rb_node_next(rb_tree *tree, rb_node *node) {
+    rb_node *next = rb_tree_successor(tree, node);
+    return (next != tree->nil) ? next : NULL;
+}
+
+/* rb_node_root - returns the root node of a @tree, or 'NULL' if tree is empty */
+rb_node *
+rb_node_root(rb_tree *tree) {
+    rb_node *node = tree->root->left;
+    return (node != tree->nil) ? node : NULL;
+}
+
+/* rb_node_left - gets the left child of @node, or 'NULL' if no such node */
+rb_node *
+rb_node_left(rb_tree *tree, rb_node *node) {
+    rb_node *left = node->left;
+    return (left != tree->nil) ? left : NULL;
+}
+
+/* rb_node_right - gets the right child of @node, or 'NULL' if no such node */
+rb_node *
+rb_node_right(rb_tree *tree, rb_node *node) {
+    rb_node *right = node->right;
+    return (right != tree->nil) ? right : NULL;
+}
+
+int
+check_tree(rb_tree *tree, rb_node *node) {
+    rb_node *nil = tree->nil;
+    if (node == nil) {
+        assert(!node->red);
+        return 1;
+    }
+    if (node->left != nil) {
+        assert(COMPARE(tree, node, node->left) >= 0);
+        assert(node->left->parent == node);
+    }
+    if (node->right != nil) {
+        assert(COMPARE(tree, node, node->right) <= 0);
+        assert(node->right->parent == node);
+    }
+    if (node->red) {
+        assert(!node->left->red && !node->right->red);
+    }
+    int hb_left = check_tree(tree, node->left);
+    int hb_right = check_tree(tree, node->right);
+    assert(hb_left == hb_right);
+    int hb = hb_left;
+    if (!node->red) {
+        hb ++;
+    }
+    return hb;
+}
+
+static void *
+check_safe_kmalloc(size_t size) {
+    void *ret = kmalloc(size);
+    assert(ret != NULL);
+    return ret;
+}
+
+struct check_data {
+    long data;
+    rb_node rb_link;
+};
+
+#define rbn2data(node)              \
+    (to_struct(node, struct check_data, rb_link))
+
+static inline int
+check_compare1(rb_node *node1, rb_node *node2) {
+    return rbn2data(node1)->data - rbn2data(node2)->data;
+}
+
+static inline int
+check_compare2(rb_node *node, void *key) {
+    return rbn2data(node)->data - (long)key;
+}
+
+void
+check_rb_tree(void) {
+    rb_tree *tree = rb_tree_create(check_compare1);
+    assert(tree != NULL);
+
+    rb_node *nil = tree->nil, *root = tree->root;
+    assert(!nil->red && root->left == nil);
+
+    int total = 1000;
+    struct check_data **all = check_safe_kmalloc(sizeof(struct check_data *) * total);
+
+    long i;
+    for (i = 0; i < total; i ++) {
+        all[i] = check_safe_kmalloc(sizeof(struct check_data));
+        all[i]->data = i;
+    }
+
+    int *mark = check_safe_kmalloc(sizeof(int) * total);
+    memset(mark, 0, sizeof(int) * total);
+
+    for (i = 0; i < total; i ++) {
+        mark[all[i]->data] = 1;
+    }
+    for (i = 0; i < total; i ++) {
+        assert(mark[i] == 1);
+    }
+
+    for (i = 0; i < total; i ++) {
+        int j = (rand() % (total - i)) + i;
+        struct check_data *z = all[i];
+        all[i] = all[j];
+        all[j] = z;
+    }
+
+    memset(mark, 0, sizeof(int) * total);
+    for (i = 0; i < total; i ++) {
+        mark[all[i]->data] = 1;
+    }
+    for (i = 0; i < total; i ++) {
+        assert(mark[i] == 1);
+    }
+
+    for (i = 0; i < total; i ++) {
+        rb_insert(tree, &(all[i]->rb_link));
+        check_tree(tree, root->left);
+    }
+
+    rb_node *node;
+    for (i = 0; i < total; i ++) {
+        node = rb_search(tree, check_compare2, (void *)(all[i]->data));
+        assert(node != NULL && node == &(all[i]->rb_link));
+    }
+
+    for (i = 0; i < total; i ++) {
+        node = rb_search(tree, check_compare2, (void *)i);
+        assert(node != NULL && rbn2data(node)->data == i);
+        rb_delete(tree, node);
+        check_tree(tree, root->left);
+    }
+
+    assert(!nil->red && root->left == nil);
+
+    long max = 32;
+    if (max > total) {
+        max = total;
+    }
+
+    for (i = 0; i < max; i ++) {
+        all[i]->data = max;
+        rb_insert(tree, &(all[i]->rb_link));
+        check_tree(tree, root->left);
+    }
+
+    for (i = 0; i < max; i ++) {
+        node = rb_search(tree, check_compare2, (void *)max);
+        assert(node != NULL && rbn2data(node)->data == max);
+        rb_delete(tree, node);
+        check_tree(tree, root->left);
+    }
+
+    assert(rb_tree_empty(tree));
+
+    for (i = 0; i < total; i ++) {
+        rb_insert(tree, &(all[i]->rb_link));
+        check_tree(tree, root->left);
+    }
+
+    rb_tree_destroy(tree);
+
+    for (i = 0; i < total; i ++) {
+        kfree(all[i]);
+    }
+
+    kfree(mark);
+    kfree(all);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.h b/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.h
new file mode 100644
index 0000000..a2aa9aa
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/libs/rb_tree.h
@@ -0,0 +1,32 @@
+#ifndef __KERN_LIBS_RB_TREE_H__
+#define __KERN_LIBS_RB_TREE_H__
+
+#include <defs.h>
+
+typedef struct rb_node {
+    bool red;                           // if red = 0, it's a black node
+    struct rb_node *parent;
+    struct rb_node *left, *right;
+} rb_node;
+
+typedef struct rb_tree {
+    // compare function should return -1 if *node1 < *node2, 1 if *node1 > *node2, and 0 otherwise
+    int (*compare)(rb_node *node1, rb_node *node2);
+    struct rb_node *nil, *root;
+} rb_tree;
+
+rb_tree *rb_tree_create(int (*compare)(rb_node *node1, rb_node *node2));
+void rb_tree_destroy(rb_tree *tree);
+void rb_insert(rb_tree *tree, rb_node *node);
+void rb_delete(rb_tree *tree, rb_node *node);
+rb_node *rb_search(rb_tree *tree, int (*compare)(rb_node *node, void *key), void *key);
+rb_node *rb_node_prev(rb_tree *tree, rb_node *node);
+rb_node *rb_node_next(rb_tree *tree, rb_node *node);
+rb_node *rb_node_root(rb_tree *tree);
+rb_node *rb_node_left(rb_tree *tree, rb_node *node);
+rb_node *rb_node_right(rb_tree *tree, rb_node *node);
+
+void check_rb_tree(void);
+
+#endif /* !__KERN_LIBS_RBTREE_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/libs/readline.c b/related_info/lab5/lab5-spoc-discuss/kern/libs/readline.c
new file mode 100644
index 0000000..cc1eddb
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/libs/readline.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#define BUFSIZE 1024
+static char buf[BUFSIZE];
+
+/* *
+ * readline - get a line from stdin
+ * @prompt:     the string to be written to stdout
+ *
+ * The readline() function will write the input string @prompt to
+ * stdout first. If the @prompt is NULL or the empty string,
+ * no prompt is issued.
+ *
+ * This function will keep on reading characters and saving them to buffer
+ * 'buf' until '\n' or '\r' is encountered.
+ *
+ * Note that, if the length of string that will be read is longer than
+ * buffer size, the end of string will be discarded.
+ *
+ * The readline() function returns the text of the line read. If some errors
+ * are happened, NULL is returned. The return value is a global variable,
+ * thus it should be copied before it is used.
+ * */
+char *
+readline(const char *prompt) {
+    if (prompt != NULL) {
+        cprintf("%s", prompt);
+    }
+    int i = 0, c;
+    while (1) {
+        c = getchar();
+        if (c < 0) {
+            return NULL;
+        }
+        else if (c >= ' ' && i < BUFSIZE - 1) {
+            cputchar(c);
+            buf[i ++] = c;
+        }
+        else if (c == '\b' && i > 0) {
+            cputchar(c);
+            i --;
+        }
+        else if (c == '\n' || c == '\r') {
+            cputchar(c);
+            buf[i] = '\0';
+            return buf;
+        }
+    }
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/libs/stdio.c b/related_info/lab5/lab5-spoc-discuss/kern/libs/stdio.c
new file mode 100644
index 0000000..5efefcd
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/libs/stdio.c
@@ -0,0 +1,78 @@
+#include <defs.h>
+#include <stdio.h>
+#include <console.h>
+
+/* HIGH level console I/O */
+
+/* *
+ * cputch - writes a single character @c to stdout, and it will
+ * increace the value of counter pointed by @cnt.
+ * */
+static void
+cputch(int c, int *cnt) {
+    cons_putc(c);
+    (*cnt) ++;
+}
+
+/* *
+ * vcprintf - format a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want cprintf() instead.
+ * */
+int
+vcprintf(const char *fmt, va_list ap) {
+    int cnt = 0;
+    vprintfmt((void*)cputch, &cnt, fmt, ap);
+    return cnt;
+}
+
+/* *
+ * cprintf - formats a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ * */
+int
+cprintf(const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vcprintf(fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* cputchar - writes a single character to stdout */
+void
+cputchar(int c) {
+    cons_putc(c);
+}
+
+/* *
+ * cputs- writes the string pointed by @str to stdout and
+ * appends a newline character.
+ * */
+int
+cputs(const char *str) {
+    int cnt = 0;
+    char c;
+    while ((c = *str ++) != '\0') {
+        cputch(c, &cnt);
+    }
+    cputch('\n', &cnt);
+    return cnt;
+}
+
+/* getchar - reads a single non-zero character from stdin */
+int
+getchar(void) {
+    int c;
+    while ((c = cons_getc()) == 0)
+        /* do nothing */;
+    return c;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.c
new file mode 100644
index 0000000..b3ecef1
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.c
@@ -0,0 +1,294 @@
+#include <pmm.h>
+#include <list.h>
+#include <string.h>
+#include <default_pmm.h>
+
+/* In the first fit algorithm, the allocator keeps a list of free blocks (known as the free list) and,
+   on receiving a request for memory, scans along the list for the first block that is large enough to
+   satisfy the request. If the chosen block is significantly larger than that requested, then it is 
+   usually split, and the remainder added to the list as another free block.
+   Please see Page 196~198, Section 8.2 of Yan Wei Ming's chinese book "Data Structure -- C programming language"
+*/
+// LAB2 EXERCISE 1: YOUR CODE
+// you should rewrite functions: default_init,default_init_memmap,default_alloc_pages, default_free_pages.
+/*
+ * Details of FFMA
+ * (1) Prepare: In order to implement the First-Fit Mem Alloc (FFMA), we should manage the free mem block use some list.
+ *              The struct free_area_t is used for the management of free mem blocks. At first you should
+ *              be familiar to the struct list in list.h. struct list is a simple doubly linked list implementation.
+ *              You should know howto USE: list_init, list_add(list_add_after), list_add_before, list_del, list_next, list_prev
+ *              Another tricky method is to transform a general list struct to a special struct (such as struct page):
+ *              you can find some MACRO: le2page (in memlayout.h), (in future labs: le2vma (in vmm.h), le2proc (in proc.h),etc.)
+ * (2) default_init: you can reuse the  demo default_init fun to init the free_list and set nr_free to 0.
+ *              free_list is used to record the free mem blocks. nr_free is the total number for free mem blocks.
+ * (3) default_init_memmap:  CALL GRAPH: kern_init --> pmm_init-->page_init-->init_memmap--> pmm_manager->init_memmap
+ *              This fun is used to init a free block (with parameter: addr_base, page_number).
+ *              First you should init each page (in memlayout.h) in this free block, include:
+ *                  p->flags should be set bit PG_property (means this page is valid. In pmm_init fun (in pmm.c),
+ *                  the bit PG_reserved is setted in p->flags)
+ *                  if this page  is free and is not the first page of free block, p->property should be set to 0.
+ *                  if this page  is free and is the first page of free block, p->property should be set to total num of block.
+ *                  p->ref should be 0, because now p is free and no reference.
+ *                  We can use p->page_link to link this page to free_list, (such as: list_add_before(&free_list, &(p->page_link)); )
+ *              Finally, we should sum the number of free mem block: nr_free+=n
+ * (4) default_alloc_pages: search find a first free block (block size >=n) in free list and reszie the free block, return the addr
+ *              of malloced block.
+ *              (4.1) So you should search freelist like this:
+ *                       list_entry_t le = &free_list;
+ *                       while((le=list_next(le)) != &free_list) {
+ *                       ....
+ *                 (4.1.1) In while loop, get the struct page and check the p->property (record the num of free block) >=n?
+ *                       struct Page *p = le2page(le, page_link);
+ *                       if(p->property >= n){ ...
+ *                 (4.1.2) If we find this p, then it' means we find a free block(block size >=n), and the first n pages can be malloced.
+ *                     Some flag bits of this page should be setted: PG_reserved =1, PG_property =0
+ *                     unlink the pages from free_list
+ *                     (4.1.2.1) If (p->property >n), we should re-caluclate number of the the rest of this free block,
+ *                           (such as: le2page(le,page_link))->property = p->property - n;)
+ *                 (4.1.3)  re-caluclate nr_free (number of the the rest of all free block)
+ *                 (4.1.4)  return p
+ *               (4.2) If we can not find a free block (block size >=n), then return NULL
+ * (5) default_free_pages: relink the pages into  free list, maybe merge small free blocks into big free blocks.
+ *               (5.1) according the base addr of withdrawed blocks, search free list, find the correct position
+ *                     (from low to high addr), and insert the pages. (may use list_next, le2page, list_add_before)
+ *               (5.2) reset the fields of pages, such as p->ref, p->flags (PageProperty)
+ *               (5.3) try to merge low addr or high addr blocks. Notice: should change some pages's p->property correctly.
+ */
+free_area_t free_area;
+
+#define free_list (free_area.free_list)
+#define nr_free (free_area.nr_free)
+
+static void
+default_init(void) {
+    list_init(&free_list);
+    nr_free = 0;
+}
+
+static void
+default_init_memmap(struct Page *base, size_t n) {
+    assert(n > 0);
+    struct Page *p = base;
+    for (; p != base + n; p ++) {
+        assert(PageReserved(p));
+        p->flags = 0;
+        SetPageProperty(p);
+        p->property = 0;
+        set_page_ref(p, 0);
+        list_add_before(&free_list, &(p->page_link));
+    }
+    nr_free += n;
+    //first block
+    base->property = n;
+}
+
+static struct Page *
+default_alloc_pages(size_t n) {
+    assert(n > 0);
+    if (n > nr_free) {
+        return NULL;
+    }
+    list_entry_t *le, *len;
+    le = &free_list;
+
+    while((le=list_next(le)) != &free_list) {
+      struct Page *p = le2page(le, page_link);
+      if(p->property >= n){
+        int i;
+        for(i=0;i<n;i++){
+          len = list_next(le);
+          struct Page *pp = le2page(le, page_link);
+          SetPageReserved(pp);
+          ClearPageProperty(pp);
+          list_del(le);
+          le = len;
+        }
+        if(p->property>n){
+          (le2page(le,page_link))->property = p->property - n;
+        }
+        ClearPageProperty(p);
+        SetPageReserved(p);
+        nr_free -= n;
+        return p;
+      }
+    }
+    return NULL;
+}
+
+static void
+default_free_pages(struct Page *base, size_t n) {
+    assert(n > 0);
+    assert(PageReserved(base));
+
+    list_entry_t *le = &free_list;
+    struct Page * p;
+    while((le=list_next(le)) != &free_list) {
+      p = le2page(le, page_link);
+      if(p>base){
+        break;
+      }
+    }
+    //list_add_before(le, base->page_link);
+    for(p=base;p<base+n;p++){
+      list_add_before(le, &(p->page_link));
+    }
+    base->flags = 0;
+    set_page_ref(base, 0);
+    ClearPageProperty(base);
+    SetPageProperty(base);
+    base->property = n;
+    
+    p = le2page(le,page_link) ;
+    if( base+n == p ){
+      base->property += p->property;
+      p->property = 0;
+    }
+    le = list_prev(&(base->page_link));
+    p = le2page(le, page_link);
+    if(le!=&free_list && p==base-1){
+      while(le!=&free_list){
+        if(p->property){
+          p->property += base->property;
+          base->property = 0;
+          break;
+        }
+        le = list_prev(le);
+        p = le2page(le,page_link);
+      }
+    }
+
+    nr_free += n;
+    return ;
+}
+
+static size_t
+default_nr_free_pages(void) {
+    return nr_free;
+}
+
+static void
+basic_check(void) {
+    struct Page *p0, *p1, *p2;
+    p0 = p1 = p2 = NULL;
+    assert((p0 = alloc_page()) != NULL);
+    assert((p1 = alloc_page()) != NULL);
+    assert((p2 = alloc_page()) != NULL);
+
+    assert(p0 != p1 && p0 != p2 && p1 != p2);
+    assert(page_ref(p0) == 0 && page_ref(p1) == 0 && page_ref(p2) == 0);
+
+    assert(page2pa(p0) < npage * PGSIZE);
+    assert(page2pa(p1) < npage * PGSIZE);
+    assert(page2pa(p2) < npage * PGSIZE);
+
+    list_entry_t free_list_store = free_list;
+    list_init(&free_list);
+    assert(list_empty(&free_list));
+
+    unsigned int nr_free_store = nr_free;
+    nr_free = 0;
+
+    assert(alloc_page() == NULL);
+
+    free_page(p0);
+    free_page(p1);
+    free_page(p2);
+    assert(nr_free == 3);
+
+    assert((p0 = alloc_page()) != NULL);
+    assert((p1 = alloc_page()) != NULL);
+    assert((p2 = alloc_page()) != NULL);
+
+    assert(alloc_page() == NULL);
+
+    free_page(p0);
+    assert(!list_empty(&free_list));
+
+    struct Page *p;
+    assert((p = alloc_page()) == p0);
+    assert(alloc_page() == NULL);
+
+    assert(nr_free == 0);
+    free_list = free_list_store;
+    nr_free = nr_free_store;
+
+    free_page(p);
+    free_page(p1);
+    free_page(p2);
+}
+
+// LAB2: below code is used to check the first fit allocation algorithm (your EXERCISE 1) 
+// NOTICE: You SHOULD NOT CHANGE basic_check, default_check functions!
+static void
+default_check(void) {
+    int count = 0, total = 0;
+    list_entry_t *le = &free_list;
+    while ((le = list_next(le)) != &free_list) {
+        struct Page *p = le2page(le, page_link);
+        assert(PageProperty(p));
+        count ++, total += p->property;
+    }
+    assert(total == nr_free_pages());
+
+    basic_check();
+
+    struct Page *p0 = alloc_pages(5), *p1, *p2;
+    assert(p0 != NULL);
+    assert(!PageProperty(p0));
+
+    list_entry_t free_list_store = free_list;
+    list_init(&free_list);
+    assert(list_empty(&free_list));
+    assert(alloc_page() == NULL);
+
+    unsigned int nr_free_store = nr_free;
+    nr_free = 0;
+
+    free_pages(p0 + 2, 3);
+    assert(alloc_pages(4) == NULL);
+    assert(PageProperty(p0 + 2) && p0[2].property == 3);
+    assert((p1 = alloc_pages(3)) != NULL);
+    assert(alloc_page() == NULL);
+    assert(p0 + 2 == p1);
+
+    p2 = p0 + 1;
+    free_page(p0);
+    free_pages(p1, 3);
+    assert(PageProperty(p0) && p0->property == 1);
+    assert(PageProperty(p1) && p1->property == 3);
+
+    assert((p0 = alloc_page()) == p2 - 1);
+    free_page(p0);
+    assert((p0 = alloc_pages(2)) == p2 + 1);
+
+    free_pages(p0, 2);
+    free_page(p2);
+
+    assert((p0 = alloc_pages(5)) != NULL);
+    assert(alloc_page() == NULL);
+
+    assert(nr_free == 0);
+    nr_free = nr_free_store;
+
+    free_list = free_list_store;
+    free_pages(p0, 5);
+
+    le = &free_list;
+    while ((le = list_next(le)) != &free_list) {
+        struct Page *p = le2page(le, page_link);
+        count --, total -= p->property;
+    }
+    assert(count == 0);
+    assert(total == 0);
+}
+
+const struct pmm_manager default_pmm_manager = {
+    .name = "default_pmm_manager",
+    .init = default_init,
+    .init_memmap = default_init_memmap,
+    .alloc_pages = default_alloc_pages,
+    .free_pages = default_free_pages,
+    .nr_free_pages = default_nr_free_pages,
+    .check = default_check,
+};
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.h
new file mode 100644
index 0000000..5f4e6fc
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/default_pmm.h
@@ -0,0 +1,9 @@
+#ifndef __KERN_MM_DEFAULT_PMM_H__
+#define  __KERN_MM_DEFAULT_PMM_H__
+
+#include <pmm.h>
+
+extern const struct pmm_manager default_pmm_manager;
+extern free_area_t free_area;
+#endif /* ! __KERN_MM_DEFAULT_PMM_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.c
new file mode 100644
index 0000000..dad888f
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.c
@@ -0,0 +1,310 @@
+#include <defs.h>
+#include <list.h>
+#include <memlayout.h>
+#include <assert.h>
+#include <kmalloc.h>
+#include <sync.h>
+#include <pmm.h>
+#include <stdio.h>
+
+/*
+ * SLOB Allocator: Simple List Of Blocks
+ *
+ * Matt Mackall <mpm@selenic.com> 12/30/03
+ *
+ * How SLOB works:
+ *
+ * The core of SLOB is a traditional K&R style heap allocator, with
+ * support for returning aligned objects. The granularity of this
+ * allocator is 8 bytes on x86, though it's perhaps possible to reduce
+ * this to 4 if it's deemed worth the effort. The slob heap is a
+ * singly-linked list of pages from __get_free_page, grown on demand
+ * and allocation from the heap is currently first-fit.
+ *
+ * Above this is an implementation of kmalloc/kfree. Blocks returned
+ * from kmalloc are 8-byte aligned and prepended with a 8-byte header.
+ * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
+ * __get_free_pages directly so that it can return page-aligned blocks
+ * and keeps a linked list of such pages and their orders. These
+ * objects are detected in kfree() by their page alignment.
+ *
+ * SLAB is emulated on top of SLOB by simply calling constructors and
+ * destructors for every SLAB allocation. Objects are returned with
+ * the 8-byte alignment unless the SLAB_MUST_HWCACHE_ALIGN flag is
+ * set, in which case the low-level allocator will fragment blocks to
+ * create the proper alignment. Again, objects of page-size or greater
+ * are allocated by calling __get_free_pages. As SLAB objects know
+ * their size, no separate size bookkeeping is necessary and there is
+ * essentially no allocation space overhead.
+ */
+
+
+//some helper
+#define spin_lock_irqsave(l, f) local_intr_save(f)
+#define spin_unlock_irqrestore(l, f) local_intr_restore(f)
+typedef unsigned int gfp_t;
+#ifndef PAGE_SIZE
+#define PAGE_SIZE PGSIZE
+#endif
+
+#ifndef L1_CACHE_BYTES
+#define L1_CACHE_BYTES 64
+#endif
+
+#ifndef ALIGN
+#define ALIGN(addr,size)   (((addr)+(size)-1)&(~((size)-1))) 
+#endif
+
+
+struct slob_block {
+	int units;
+	struct slob_block *next;
+};
+typedef struct slob_block slob_t;
+
+#define SLOB_UNIT sizeof(slob_t)
+#define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)
+#define SLOB_ALIGN L1_CACHE_BYTES
+
+struct bigblock {
+	int order;
+	void *pages;
+	struct bigblock *next;
+};
+typedef struct bigblock bigblock_t;
+
+static slob_t arena = { .next = &arena, .units = 1 };
+static slob_t *slobfree = &arena;
+static bigblock_t *bigblocks;
+
+
+static void* __slob_get_free_pages(gfp_t gfp, int order)
+{
+  struct Page * page = alloc_pages(1 << order);
+  if(!page)
+    return NULL;
+  return page2kva(page);
+}
+
+#define __slob_get_free_page(gfp) __slob_get_free_pages(gfp, 0)
+
+static inline void __slob_free_pages(unsigned long kva, int order)
+{
+  free_pages(kva2page(kva), 1 << order);
+}
+
+static void slob_free(void *b, int size);
+
+static void *slob_alloc(size_t size, gfp_t gfp, int align)
+{
+  assert( (size + SLOB_UNIT) < PAGE_SIZE );
+
+	slob_t *prev, *cur, *aligned = 0;
+	int delta = 0, units = SLOB_UNITS(size);
+	unsigned long flags;
+
+	spin_lock_irqsave(&slob_lock, flags);
+	prev = slobfree;
+	for (cur = prev->next; ; prev = cur, cur = cur->next) {
+		if (align) {
+			aligned = (slob_t *)ALIGN((unsigned long)cur, align);
+			delta = aligned - cur;
+		}
+		if (cur->units >= units + delta) { /* room enough? */
+			if (delta) { /* need to fragment head to align? */
+				aligned->units = cur->units - delta;
+				aligned->next = cur->next;
+				cur->next = aligned;
+				cur->units = delta;
+				prev = cur;
+				cur = aligned;
+			}
+
+			if (cur->units == units) /* exact fit? */
+				prev->next = cur->next; /* unlink */
+			else { /* fragment */
+				prev->next = cur + units;
+				prev->next->units = cur->units - units;
+				prev->next->next = cur->next;
+				cur->units = units;
+			}
+
+			slobfree = prev;
+			spin_unlock_irqrestore(&slob_lock, flags);
+			return cur;
+		}
+		if (cur == slobfree) {
+			spin_unlock_irqrestore(&slob_lock, flags);
+
+			if (size == PAGE_SIZE) /* trying to shrink arena? */
+				return 0;
+
+			cur = (slob_t *)__slob_get_free_page(gfp);
+			if (!cur)
+				return 0;
+
+			slob_free(cur, PAGE_SIZE);
+			spin_lock_irqsave(&slob_lock, flags);
+			cur = slobfree;
+		}
+	}
+}
+
+static void slob_free(void *block, int size)
+{
+	slob_t *cur, *b = (slob_t *)block;
+	unsigned long flags;
+
+	if (!block)
+		return;
+
+	if (size)
+		b->units = SLOB_UNITS(size);
+
+	/* Find reinsertion point */
+	spin_lock_irqsave(&slob_lock, flags);
+	for (cur = slobfree; !(b > cur && b < cur->next); cur = cur->next)
+		if (cur >= cur->next && (b > cur || b < cur->next))
+			break;
+
+	if (b + b->units == cur->next) {
+		b->units += cur->next->units;
+		b->next = cur->next->next;
+	} else
+		b->next = cur->next;
+
+	if (cur + cur->units == b) {
+		cur->units += b->units;
+		cur->next = b->next;
+	} else
+		cur->next = b;
+
+	slobfree = cur;
+
+	spin_unlock_irqrestore(&slob_lock, flags);
+}
+
+
+
+void check_slab(void) {
+  cprintf("check_slab() success\n");
+}
+
+void
+slab_init(void) {
+  cprintf("use SLOB allocator\n");
+  check_slab();
+}
+
+inline void 
+kmalloc_init(void) {
+    slab_init();
+    cprintf("kmalloc_init() succeeded!\n");
+}
+
+size_t
+slab_allocated(void) {
+  return 0;
+}
+
+size_t
+kallocated(void) {
+   return slab_allocated();
+}
+
+static int find_order(int size)
+{
+	int order = 0;
+	for ( ; size > 4096 ; size >>=1)
+		order++;
+	return order;
+}
+
+static void *__kmalloc(size_t size, gfp_t gfp)
+{
+	slob_t *m;
+	bigblock_t *bb;
+	unsigned long flags;
+
+	if (size < PAGE_SIZE - SLOB_UNIT) {
+		m = slob_alloc(size + SLOB_UNIT, gfp, 0);
+		return m ? (void *)(m + 1) : 0;
+	}
+
+	bb = slob_alloc(sizeof(bigblock_t), gfp, 0);
+	if (!bb)
+		return 0;
+
+	bb->order = find_order(size);
+	bb->pages = (void *)__slob_get_free_pages(gfp, bb->order);
+
+	if (bb->pages) {
+		spin_lock_irqsave(&block_lock, flags);
+		bb->next = bigblocks;
+		bigblocks = bb;
+		spin_unlock_irqrestore(&block_lock, flags);
+		return bb->pages;
+	}
+
+	slob_free(bb, sizeof(bigblock_t));
+	return 0;
+}
+
+void *
+kmalloc(size_t size)
+{
+  return __kmalloc(size, 0);
+}
+
+
+void kfree(void *block)
+{
+	bigblock_t *bb, **last = &bigblocks;
+	unsigned long flags;
+
+	if (!block)
+		return;
+
+	if (!((unsigned long)block & (PAGE_SIZE-1))) {
+		/* might be on the big block list */
+		spin_lock_irqsave(&block_lock, flags);
+		for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) {
+			if (bb->pages == block) {
+				*last = bb->next;
+				spin_unlock_irqrestore(&block_lock, flags);
+				__slob_free_pages((unsigned long)block, bb->order);
+				slob_free(bb, sizeof(bigblock_t));
+				return;
+			}
+		}
+		spin_unlock_irqrestore(&block_lock, flags);
+	}
+
+	slob_free((slob_t *)block - 1, 0);
+	return;
+}
+
+
+unsigned int ksize(const void *block)
+{
+	bigblock_t *bb;
+	unsigned long flags;
+
+	if (!block)
+		return 0;
+
+	if (!((unsigned long)block & (PAGE_SIZE-1))) {
+		spin_lock_irqsave(&block_lock, flags);
+		for (bb = bigblocks; bb; bb = bb->next)
+			if (bb->pages == block) {
+				spin_unlock_irqrestore(&slob_lock, flags);
+				return PAGE_SIZE << bb->order;
+			}
+		spin_unlock_irqrestore(&block_lock, flags);
+	}
+
+	return ((slob_t *)block - 1)->units * SLOB_UNIT;
+}
+
+
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.h
new file mode 100644
index 0000000..8617975
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/kmalloc.h
@@ -0,0 +1,16 @@
+#ifndef __KERN_MM_SLAB_H__
+#define __KERN_MM_SLAB_H__
+
+#include <defs.h>
+
+#define KMALLOC_MAX_ORDER       10
+
+void kmalloc_init(void);
+
+void *kmalloc(size_t n);
+void kfree(void *objp);
+
+size_t kallocated(void);
+
+#endif /* !__KERN_MM_SLAB_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/memlayout.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/memlayout.h
new file mode 100644
index 0000000..825dd66
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/memlayout.h
@@ -0,0 +1,169 @@
+#ifndef __KERN_MM_MEMLAYOUT_H__
+#define __KERN_MM_MEMLAYOUT_H__
+
+/* This file contains the definitions for memory management in our OS. */
+
+/* global segment number */
+#define SEG_KTEXT   1
+#define SEG_KDATA   2
+#define SEG_UTEXT   3
+#define SEG_UDATA   4
+#define SEG_TSS     5
+
+/* global descrptor numbers */
+#define GD_KTEXT    ((SEG_KTEXT) << 3)      // kernel text
+#define GD_KDATA    ((SEG_KDATA) << 3)      // kernel data
+#define GD_UTEXT    ((SEG_UTEXT) << 3)      // user text
+#define GD_UDATA    ((SEG_UDATA) << 3)      // user data
+#define GD_TSS      ((SEG_TSS) << 3)        // task segment selector
+
+#define DPL_KERNEL  (0)
+#define DPL_USER    (3)
+
+#define KERNEL_CS   ((GD_KTEXT) | DPL_KERNEL)
+#define KERNEL_DS   ((GD_KDATA) | DPL_KERNEL)
+#define USER_CS     ((GD_UTEXT) | DPL_USER)
+#define USER_DS     ((GD_UDATA) | DPL_USER)
+
+/* *
+ * Virtual memory map:                                          Permissions
+ *                                                              kernel/user
+ *
+ *     4G ------------------> +---------------------------------+
+ *                            |                                 |
+ *                            |         Empty Memory (*)        |
+ *                            |                                 |
+ *                            +---------------------------------+ 0xFB000000
+ *                            |   Cur. Page Table (Kern, RW)    | RW/-- PTSIZE
+ *     VPT -----------------> +---------------------------------+ 0xFAC00000
+ *                            |        Invalid Memory (*)       | --/--
+ *     KERNTOP -------------> +---------------------------------+ 0xF8000000
+ *                            |                                 |
+ *                            |    Remapped Physical Memory     | RW/-- KMEMSIZE
+ *                            |                                 |
+ *     KERNBASE ------------> +---------------------------------+ 0xC0000000
+ *                            |        Invalid Memory (*)       | --/--
+ *     USERTOP -------------> +---------------------------------+ 0xB0000000
+ *                            |           User stack            |
+ *                            +---------------------------------+
+ *                            |                                 |
+ *                            :                                 :
+ *                            |         ~~~~~~~~~~~~~~~~        |
+ *                            :                                 :
+ *                            |                                 |
+ *                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *                            |       User Program & Heap       |
+ *     UTEXT ---------------> +---------------------------------+ 0x00800000
+ *                            |        Invalid Memory (*)       | --/--
+ *                            |  - - - - - - - - - - - - - - -  |
+ *                            |    User STAB Data (optional)    |
+ *     USERBASE, USTAB------> +---------------------------------+ 0x00200000
+ *                            |        Invalid Memory (*)       | --/--
+ *     0 -------------------> +---------------------------------+ 0x00000000
+ * (*) Note: The kernel ensures that "Invalid Memory" is *never* mapped.
+ *     "Empty Memory" is normally unmapped, but user programs may map pages
+ *     there if desired.
+ *
+ * */
+
+/* All physical memory mapped at this address */
+#define KERNBASE            0xC0000000
+#define KMEMSIZE            0x38000000                  // the maximum amount of physical memory
+#define KERNTOP             (KERNBASE + KMEMSIZE)
+
+/* *
+ * Virtual page table. Entry PDX[VPT] in the PD (Page Directory) contains
+ * a pointer to the page directory itself, thereby turning the PD into a page
+ * table, which maps all the PTEs (Page Table Entry) containing the page mappings
+ * for the entire virtual address space into that 4 Meg region starting at VPT.
+ * */
+#define VPT                 0xFAC00000
+
+#define KSTACKPAGE          2                           // # of pages in kernel stack
+#define KSTACKSIZE          (KSTACKPAGE * PGSIZE)       // sizeof kernel stack
+
+#define USERTOP             0xB0000000
+#define USTACKTOP           USERTOP
+#define USTACKPAGE          256                         // # of pages in user stack
+#define USTACKSIZE          (USTACKPAGE * PGSIZE)       // sizeof user stack
+
+#define USERBASE            0x00200000
+#define UTEXT               0x00800000                  // where user programs generally begin
+#define USTAB               USERBASE                    // the location of the user STABS data structure
+
+#define USER_ACCESS(start, end)                     \
+(USERBASE <= (start) && (start) < (end) && (end) <= USERTOP)
+
+#define KERN_ACCESS(start, end)                     \
+(KERNBASE <= (start) && (start) < (end) && (end) <= KERNTOP)
+
+#ifndef __ASSEMBLER__
+
+#include <defs.h>
+#include <atomic.h>
+#include <list.h>
+
+typedef uintptr_t pte_t;
+typedef uintptr_t pde_t;
+typedef pte_t swap_entry_t; //the pte can also be a swap entry
+
+// some constants for bios interrupt 15h AX = 0xE820
+#define E820MAX             20      // number of entries in E820MAP
+#define E820_ARM            1       // address range memory
+#define E820_ARR            2       // address range reserved
+
+struct e820map {
+    int nr_map;
+    struct {
+        uint64_t addr;
+        uint64_t size;
+        uint32_t type;
+    } __attribute__((packed)) map[E820MAX];
+};
+
+/* *
+ * struct Page - Page descriptor structures. Each Page describes one
+ * physical page. In kern/mm/pmm.h, you can find lots of useful functions
+ * that convert Page to other data types, such as phyical address.
+ * */
+struct Page {
+    int ref;                        // page frame's reference counter
+    uint32_t flags;                 // array of flags that describe the status of the page frame
+    unsigned int property;          // used in buddy system, stores the order (the X in 2^X) of the continuous memory block
+    int zone_num;                   // used in buddy system, the No. of zone which the page belongs to
+    list_entry_t page_link;         // free list link
+    list_entry_t pra_page_link;     // used for pra (page replace algorithm)
+    uintptr_t pra_vaddr;            // used for pra (page replace algorithm)
+};
+
+/* Flags describing the status of a page frame */
+#define PG_reserved                 0       // the page descriptor is reserved for kernel or unusable
+#define PG_property                 1       // the member 'property' is valid
+
+#define SetPageReserved(page)       set_bit(PG_reserved, &((page)->flags))
+#define ClearPageReserved(page)     clear_bit(PG_reserved, &((page)->flags))
+#define PageReserved(page)          test_bit(PG_reserved, &((page)->flags))
+#define SetPageProperty(page)       set_bit(PG_property, &((page)->flags))
+#define ClearPageProperty(page)     clear_bit(PG_property, &((page)->flags))
+#define PageProperty(page)          test_bit(PG_property, &((page)->flags))
+
+// convert list entry to page
+#define le2page(le, member)                 \
+    to_struct((le), struct Page, member)
+
+/* free_area_t - maintains a doubly linked list to record free (unused) pages */
+typedef struct {
+    list_entry_t free_list;         // the list header
+    unsigned int nr_free;           // # of free pages in this free list
+} free_area_t;
+
+/* for slab style kmalloc */
+#define PG_slab                     2       // page frame is included in a slab
+#define SetPageSlab(page)           set_bit(PG_slab, &((page)->flags))
+#define ClearPageSlab(page)         clear_bit(PG_slab, &((page)->flags))
+#define PageSlab(page)              test_bit(PG_slab, &((page)->flags))
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* !__KERN_MM_MEMLAYOUT_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/mmu.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/mmu.h
new file mode 100644
index 0000000..3858ad9
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/mmu.h
@@ -0,0 +1,272 @@
+#ifndef __KERN_MM_MMU_H__
+#define __KERN_MM_MMU_H__
+
+/* Eflags register */
+#define FL_CF           0x00000001  // Carry Flag
+#define FL_PF           0x00000004  // Parity Flag
+#define FL_AF           0x00000010  // Auxiliary carry Flag
+#define FL_ZF           0x00000040  // Zero Flag
+#define FL_SF           0x00000080  // Sign Flag
+#define FL_TF           0x00000100  // Trap Flag
+#define FL_IF           0x00000200  // Interrupt Flag
+#define FL_DF           0x00000400  // Direction Flag
+#define FL_OF           0x00000800  // Overflow Flag
+#define FL_IOPL_MASK    0x00003000  // I/O Privilege Level bitmask
+#define FL_IOPL_0       0x00000000  //   IOPL == 0
+#define FL_IOPL_1       0x00001000  //   IOPL == 1
+#define FL_IOPL_2       0x00002000  //   IOPL == 2
+#define FL_IOPL_3       0x00003000  //   IOPL == 3
+#define FL_NT           0x00004000  // Nested Task
+#define FL_RF           0x00010000  // Resume Flag
+#define FL_VM           0x00020000  // Virtual 8086 mode
+#define FL_AC           0x00040000  // Alignment Check
+#define FL_VIF          0x00080000  // Virtual Interrupt Flag
+#define FL_VIP          0x00100000  // Virtual Interrupt Pending
+#define FL_ID           0x00200000  // ID flag
+
+/* Application segment type bits */
+#define STA_X           0x8         // Executable segment
+#define STA_E           0x4         // Expand down (non-executable segments)
+#define STA_C           0x4         // Conforming code segment (executable only)
+#define STA_W           0x2         // Writeable (non-executable segments)
+#define STA_R           0x2         // Readable (executable segments)
+#define STA_A           0x1         // Accessed
+
+/* System segment type bits */
+#define STS_T16A        0x1         // Available 16-bit TSS
+#define STS_LDT         0x2         // Local Descriptor Table
+#define STS_T16B        0x3         // Busy 16-bit TSS
+#define STS_CG16        0x4         // 16-bit Call Gate
+#define STS_TG          0x5         // Task Gate / Coum Transmitions
+#define STS_IG16        0x6         // 16-bit Interrupt Gate
+#define STS_TG16        0x7         // 16-bit Trap Gate
+#define STS_T32A        0x9         // Available 32-bit TSS
+#define STS_T32B        0xB         // Busy 32-bit TSS
+#define STS_CG32        0xC         // 32-bit Call Gate
+#define STS_IG32        0xE         // 32-bit Interrupt Gate
+#define STS_TG32        0xF         // 32-bit Trap Gate
+
+#ifdef __ASSEMBLER__
+
+#define SEG_NULL                                                \
+    .word 0, 0;                                                 \
+    .byte 0, 0, 0, 0
+
+#define SEG_ASM(type,base,lim)                                  \
+    .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);          \
+    .byte (((base) >> 16) & 0xff), (0x90 | (type)),             \
+        (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
+
+#else /* not __ASSEMBLER__ */
+
+#include <defs.h>
+
+/* Gate descriptors for interrupts and traps */
+struct gatedesc {
+    unsigned gd_off_15_0 : 16;      // low 16 bits of offset in segment
+    unsigned gd_ss : 16;            // segment selector
+    unsigned gd_args : 5;           // # args, 0 for interrupt/trap gates
+    unsigned gd_rsv1 : 3;           // reserved(should be zero I guess)
+    unsigned gd_type : 4;           // type(STS_{TG,IG32,TG32})
+    unsigned gd_s : 1;              // must be 0 (system)
+    unsigned gd_dpl : 2;            // descriptor(meaning new) privilege level
+    unsigned gd_p : 1;              // Present
+    unsigned gd_off_31_16 : 16;     // high bits of offset in segment
+};
+
+/* *
+ * Set up a normal interrupt/trap gate descriptor
+ *   - istrap: 1 for a trap (= exception) gate, 0 for an interrupt gate
+ *   - sel: Code segment selector for interrupt/trap handler
+ *   - off: Offset in code segment for interrupt/trap handler
+ *   - dpl: Descriptor Privilege Level - the privilege level required
+ *          for software to invoke this interrupt/trap gate explicitly
+ *          using an int instruction.
+ * */
+#define SETGATE(gate, istrap, sel, off, dpl) {               \
+        (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;      \
+        (gate).gd_ss = (sel);                                \
+        (gate).gd_args = 0;                                 \
+        (gate).gd_rsv1 = 0;                                 \
+        (gate).gd_type = (istrap) ? STS_TG32 : STS_IG32;    \
+        (gate).gd_s = 0;                                    \
+        (gate).gd_dpl = (dpl);                              \
+        (gate).gd_p = 1;                                    \
+        (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+    }
+
+/* Set up a call gate descriptor */
+#define SETCALLGATE(gate, ss, off, dpl) {                   \
+        (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;      \
+        (gate).gd_ss = (ss);                                \
+        (gate).gd_args = 0;                                 \
+        (gate).gd_rsv1 = 0;                                 \
+        (gate).gd_type = STS_CG32;                          \
+        (gate).gd_s = 0;                                    \
+        (gate).gd_dpl = (dpl);                              \
+        (gate).gd_p = 1;                                    \
+        (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+    }
+
+/* segment descriptors */
+struct segdesc {
+    unsigned sd_lim_15_0 : 16;      // low bits of segment limit
+    unsigned sd_base_15_0 : 16;     // low bits of segment base address
+    unsigned sd_base_23_16 : 8;     // middle bits of segment base address
+    unsigned sd_type : 4;           // segment type (see STS_ constants)
+    unsigned sd_s : 1;              // 0 = system, 1 = application
+    unsigned sd_dpl : 2;            // descriptor Privilege Level
+    unsigned sd_p : 1;              // present
+    unsigned sd_lim_19_16 : 4;      // high bits of segment limit
+    unsigned sd_avl : 1;            // unused (available for software use)
+    unsigned sd_rsv1 : 1;           // reserved
+    unsigned sd_db : 1;             // 0 = 16-bit segment, 1 = 32-bit segment
+    unsigned sd_g : 1;              // granularity: limit scaled by 4K when set
+    unsigned sd_base_31_24 : 8;     // high bits of segment base address
+};
+
+#define SEG_NULL                                            \
+    (struct segdesc) {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+#define SEG(type, base, lim, dpl)                           \
+    (struct segdesc) {                                      \
+        ((lim) >> 12) & 0xffff, (base) & 0xffff,            \
+        ((base) >> 16) & 0xff, type, 1, dpl, 1,             \
+        (unsigned)(lim) >> 28, 0, 0, 1, 1,                  \
+        (unsigned) (base) >> 24                             \
+    }
+
+#define SEGTSS(type, base, lim, dpl)                        \
+    (struct segdesc) {                                      \
+        (lim) & 0xffff, (base) & 0xffff,                    \
+        ((base) >> 16) & 0xff, type, 0, dpl, 1,             \
+        (unsigned) (lim) >> 16, 0, 0, 1, 0,                 \
+        (unsigned) (base) >> 24                             \
+    }
+
+/* task state segment format (as described by the Pentium architecture book) */
+struct taskstate {
+    uint32_t ts_link;       // old ts selector
+    uintptr_t ts_esp0;      // stack pointers and segment selectors
+    uint16_t ts_ss0;        // after an increase in privilege level
+    uint16_t ts_padding1;
+    uintptr_t ts_esp1;
+    uint16_t ts_ss1;
+    uint16_t ts_padding2;
+    uintptr_t ts_esp2;
+    uint16_t ts_ss2;
+    uint16_t ts_padding3;
+    uintptr_t ts_cr3;       // page directory base
+    uintptr_t ts_eip;       // saved state from last task switch
+    uint32_t ts_eflags;
+    uint32_t ts_eax;        // more saved state (registers)
+    uint32_t ts_ecx;
+    uint32_t ts_edx;
+    uint32_t ts_ebx;
+    uintptr_t ts_esp;
+    uintptr_t ts_ebp;
+    uint32_t ts_esi;
+    uint32_t ts_edi;
+    uint16_t ts_es;         // even more saved state (segment selectors)
+    uint16_t ts_padding4;
+    uint16_t ts_cs;
+    uint16_t ts_padding5;
+    uint16_t ts_ss;
+    uint16_t ts_padding6;
+    uint16_t ts_ds;
+    uint16_t ts_padding7;
+    uint16_t ts_fs;
+    uint16_t ts_padding8;
+    uint16_t ts_gs;
+    uint16_t ts_padding9;
+    uint16_t ts_ldt;
+    uint16_t ts_padding10;
+    uint16_t ts_t;          // trap on task switch
+    uint16_t ts_iomb;       // i/o map base address
+} __attribute__((packed));
+
+#endif /* !__ASSEMBLER__ */
+
+// A linear address 'la' has a three-part structure as follows:
+//
+// +--------10------+-------10-------+---------12----------+
+// | Page Directory |   Page Table   | Offset within Page  |
+// |      Index     |     Index      |                     |
+// +----------------+----------------+---------------------+
+//  \--- PDX(la) --/ \--- PTX(la) --/ \---- PGOFF(la) ----/
+//  \----------- PPN(la) -----------/
+//
+// The PDX, PTX, PGOFF, and PPN macros decompose linear addresses as shown.
+// To construct a linear address la from PDX(la), PTX(la), and PGOFF(la),
+// use PGADDR(PDX(la), PTX(la), PGOFF(la)).
+
+// page directory index
+#define PDX(la) ((((uintptr_t)(la)) >> PDXSHIFT) & 0x3FF)
+
+// page table index
+#define PTX(la) ((((uintptr_t)(la)) >> PTXSHIFT) & 0x3FF)
+
+// page number field of address
+#define PPN(la) (((uintptr_t)(la)) >> PTXSHIFT)
+
+// offset in page
+#define PGOFF(la) (((uintptr_t)(la)) & 0xFFF)
+
+// construct linear address from indexes and offset
+#define PGADDR(d, t, o) ((uintptr_t)((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))
+
+// address in page table or page directory entry
+#define PTE_ADDR(pte)   ((uintptr_t)(pte) & ~0xFFF)
+#define PDE_ADDR(pde)   PTE_ADDR(pde)
+
+/* page directory and page table constants */
+#define NPDEENTRY       1024                    // page directory entries per page directory
+#define NPTEENTRY       1024                    // page table entries per page table
+
+#define PGSIZE          4096                    // bytes mapped by a page
+#define PGSHIFT         12                      // log2(PGSIZE)
+#define PTSIZE          (PGSIZE * NPTEENTRY)    // bytes mapped by a page directory entry
+#define PTSHIFT         22                      // log2(PTSIZE)
+
+#define PTXSHIFT        12                      // offset of PTX in a linear address
+#define PDXSHIFT        22                      // offset of PDX in a linear address
+
+/* page table/directory entry flags */
+#define PTE_P           0x001                   // Present
+#define PTE_W           0x002                   // Writeable
+#define PTE_U           0x004                   // User
+#define PTE_PWT         0x008                   // Write-Through
+#define PTE_PCD         0x010                   // Cache-Disable
+#define PTE_A           0x020                   // Accessed
+#define PTE_D           0x040                   // Dirty
+#define PTE_PS          0x080                   // Page Size
+#define PTE_MBZ         0x180                   // Bits must be zero
+#define PTE_AVAIL       0xE00                   // Available for software use
+                                                // The PTE_AVAIL bits aren't used by the kernel or interpreted by the
+                                                // hardware, so user processes are allowed to set them arbitrarily.
+
+#define PTE_USER        (PTE_U | PTE_W | PTE_P)
+
+/* Control Register flags */
+#define CR0_PE          0x00000001              // Protection Enable
+#define CR0_MP          0x00000002              // Monitor coProcessor
+#define CR0_EM          0x00000004              // Emulation
+#define CR0_TS          0x00000008              // Task Switched
+#define CR0_ET          0x00000010              // Extension Type
+#define CR0_NE          0x00000020              // Numeric Errror
+#define CR0_WP          0x00010000              // Write Protect
+#define CR0_AM          0x00040000              // Alignment Mask
+#define CR0_NW          0x20000000              // Not Writethrough
+#define CR0_CD          0x40000000              // Cache Disable
+#define CR0_PG          0x80000000              // Paging
+
+#define CR4_PCE         0x00000100              // Performance counter enable
+#define CR4_MCE         0x00000040              // Machine Check Enable
+#define CR4_PSE         0x00000010              // Page Size Extensions
+#define CR4_DE          0x00000008              // Debugging Extensions
+#define CR4_TSD         0x00000004              // Time Stamp Disable
+#define CR4_PVI         0x00000002              // Protected-Mode Virtual Interrupts
+#define CR4_VME         0x00000001              // V86 Mode Extensions
+
+#endif /* !__KERN_MM_MMU_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.c
new file mode 100644
index 0000000..cf9fa77
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.c
@@ -0,0 +1,785 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <pmm.h>
+#include <default_pmm.h>
+#include <sync.h>
+#include <error.h>
+#include <swap.h>
+#include <vmm.h>
+#include <kmalloc.h>
+
+/* *
+ * Task State Segment:
+ *
+ * The TSS may reside anywhere in memory. A special segment register called
+ * the Task Register (TR) holds a segment selector that points a valid TSS
+ * segment descriptor which resides in the GDT. Therefore, to use a TSS
+ * the following must be done in function gdt_init:
+ *   - create a TSS descriptor entry in GDT
+ *   - add enough information to the TSS in memory as needed
+ *   - load the TR register with a segment selector for that segment
+ *
+ * There are several fileds in TSS for specifying the new stack pointer when a
+ * privilege level change happens. But only the fields SS0 and ESP0 are useful
+ * in our os kernel.
+ *
+ * The field SS0 contains the stack segment selector for CPL = 0, and the ESP0
+ * contains the new ESP value for CPL = 0. When an interrupt happens in protected
+ * mode, the x86 CPU will look in the TSS for SS0 and ESP0 and load their value
+ * into SS and ESP respectively.
+ * */
+static struct taskstate ts = {0};
+
+// virtual address of physicall page array
+struct Page *pages;
+// amount of physical memory (in pages)
+size_t npage = 0;
+
+// virtual address of boot-time page directory
+pde_t *boot_pgdir = NULL;
+// physical address of boot-time page directory
+uintptr_t boot_cr3;
+
+// physical memory management
+const struct pmm_manager *pmm_manager;
+
+/* *
+ * The page directory entry corresponding to the virtual address range
+ * [VPT, VPT + PTSIZE) points to the page directory itself. Thus, the page
+ * directory is treated as a page table as well as a page directory.
+ *
+ * One result of treating the page directory as a page table is that all PTEs
+ * can be accessed though a "virtual page table" at virtual address VPT. And the
+ * PTE for number n is stored in vpt[n].
+ *
+ * A second consequence is that the contents of the current page directory will
+ * always available at virtual address PGADDR(PDX(VPT), PDX(VPT), 0), to which
+ * vpd is set bellow.
+ * */
+pte_t * const vpt = (pte_t *)VPT;
+pde_t * const vpd = (pde_t *)PGADDR(PDX(VPT), PDX(VPT), 0);
+
+/* *
+ * Global Descriptor Table:
+ *
+ * The kernel and user segments are identical (except for the DPL). To load
+ * the %ss register, the CPL must equal the DPL. Thus, we must duplicate the
+ * segments for the user and the kernel. Defined as follows:
+ *   - 0x0 :  unused (always faults -- for trapping NULL far pointers)
+ *   - 0x8 :  kernel code segment
+ *   - 0x10:  kernel data segment
+ *   - 0x18:  user code segment
+ *   - 0x20:  user data segment
+ *   - 0x28:  defined for tss, initialized in gdt_init
+ * */
+static struct segdesc gdt[] = {
+    SEG_NULL,
+    [SEG_KTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_KDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_UTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_UDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_TSS]   = SEG_NULL,
+};
+
+static struct pseudodesc gdt_pd = {
+    sizeof(gdt) - 1, (uintptr_t)gdt
+};
+
+static void check_alloc_page(void);
+static void check_pgdir(void);
+static void check_boot_pgdir(void);
+
+/* *
+ * lgdt - load the global descriptor table register and reset the
+ * data/code segement registers for kernel.
+ * */
+static inline void
+lgdt(struct pseudodesc *pd) {
+    asm volatile ("lgdt (%0)" :: "r" (pd));
+    asm volatile ("movw %%ax, %%gs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%fs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%es" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ds" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ss" :: "a" (KERNEL_DS));
+    // reload cs
+    asm volatile ("ljmp %0, $1f\n 1:\n" :: "i" (KERNEL_CS));
+}
+
+/* *
+ * load_esp0 - change the ESP0 in default task state segment,
+ * so that we can use different kernel stack when we trap frame
+ * user to kernel.
+ * */
+void
+load_esp0(uintptr_t esp0) {
+    ts.ts_esp0 = esp0;
+}
+
+/* gdt_init - initialize the default GDT and TSS */
+static void
+gdt_init(void) {
+    // set boot kernel stack and default SS0
+    load_esp0((uintptr_t)bootstacktop);
+    ts.ts_ss0 = KERNEL_DS;
+
+    // initialize the TSS filed of the gdt
+    gdt[SEG_TSS] = SEGTSS(STS_T32A, (uintptr_t)&ts, sizeof(ts), DPL_KERNEL);
+
+    // reload all segment registers
+    lgdt(&gdt_pd);
+
+    // load the TSS
+    ltr(GD_TSS);
+}
+
+//init_pmm_manager - initialize a pmm_manager instance
+static void
+init_pmm_manager(void) {
+    pmm_manager = &default_pmm_manager;
+    cprintf("memory management: %s\n", pmm_manager->name);
+    pmm_manager->init();
+}
+
+//init_memmap - call pmm->init_memmap to build Page struct for free memory  
+static void
+init_memmap(struct Page *base, size_t n) {
+    pmm_manager->init_memmap(base, n);
+}
+
+//alloc_pages - call pmm->alloc_pages to allocate a continuous n*PAGESIZE memory 
+struct Page *
+alloc_pages(size_t n) {
+    struct Page *page=NULL;
+    bool intr_flag;
+    
+    while (1)
+    {
+         local_intr_save(intr_flag);
+         {
+              page = pmm_manager->alloc_pages(n);
+         }
+         local_intr_restore(intr_flag);
+
+         if (page != NULL || n > 1 || swap_init_ok == 0) break;
+         
+         extern struct mm_struct *check_mm_struct;
+         //cprintf("page %x, call swap_out in alloc_pages %d\n",page, n);
+         swap_out(check_mm_struct, n, 0);
+    }
+    //cprintf("n %d,get page %x, No %d in alloc_pages\n",n,page,(page-pages));
+    return page;
+}
+
+//free_pages - call pmm->free_pages to free a continuous n*PAGESIZE memory 
+void
+free_pages(struct Page *base, size_t n) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        pmm_manager->free_pages(base, n);
+    }
+    local_intr_restore(intr_flag);
+}
+
+//nr_free_pages - call pmm->nr_free_pages to get the size (nr*PAGESIZE) 
+//of current free memory
+size_t
+nr_free_pages(void) {
+    size_t ret;
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        ret = pmm_manager->nr_free_pages();
+    }
+    local_intr_restore(intr_flag);
+    return ret;
+}
+
+/* pmm_init - initialize the physical memory management */
+static void
+page_init(void) {
+    struct e820map *memmap = (struct e820map *)(0x8000 + KERNBASE);
+    uint64_t maxpa = 0;
+
+    cprintf("e820map:\n");
+    int i;
+    for (i = 0; i < memmap->nr_map; i ++) {
+        uint64_t begin = memmap->map[i].addr, end = begin + memmap->map[i].size;
+        cprintf("  memory: %08llx, [%08llx, %08llx], type = %d.\n",
+                memmap->map[i].size, begin, end - 1, memmap->map[i].type);
+        if (memmap->map[i].type == E820_ARM) {
+            if (maxpa < end && begin < KMEMSIZE) {
+                maxpa = end;
+            }
+        }
+    }
+    if (maxpa > KMEMSIZE) {
+        maxpa = KMEMSIZE;
+    }
+
+    extern char end[];
+
+    npage = maxpa / PGSIZE;
+    pages = (struct Page *)ROUNDUP((void *)end, PGSIZE);
+
+    for (i = 0; i < npage; i ++) {
+        SetPageReserved(pages + i);
+    }
+
+    uintptr_t freemem = PADDR((uintptr_t)pages + sizeof(struct Page) * npage);
+
+    for (i = 0; i < memmap->nr_map; i ++) {
+        uint64_t begin = memmap->map[i].addr, end = begin + memmap->map[i].size;
+        if (memmap->map[i].type == E820_ARM) {
+            if (begin < freemem) {
+                begin = freemem;
+            }
+            if (end > KMEMSIZE) {
+                end = KMEMSIZE;
+            }
+            if (begin < end) {
+                begin = ROUNDUP(begin, PGSIZE);
+                end = ROUNDDOWN(end, PGSIZE);
+                if (begin < end) {
+                    init_memmap(pa2page(begin), (end - begin) / PGSIZE);
+                }
+            }
+        }
+    }
+}
+
+static void
+enable_paging(void) {
+    lcr3(boot_cr3);
+
+    // turn on paging
+    uint32_t cr0 = rcr0();
+    cr0 |= CR0_PE | CR0_PG | CR0_AM | CR0_WP | CR0_NE | CR0_TS | CR0_EM | CR0_MP;
+    cr0 &= ~(CR0_TS | CR0_EM);
+    lcr0(cr0);
+}
+
+//boot_map_segment - setup&enable the paging mechanism
+// parameters
+//  la:   linear address of this memory need to map (after x86 segment map)
+//  size: memory size
+//  pa:   physical address of this memory
+//  perm: permission of this memory  
+static void
+boot_map_segment(pde_t *pgdir, uintptr_t la, size_t size, uintptr_t pa, uint32_t perm) {
+    assert(PGOFF(la) == PGOFF(pa));
+    size_t n = ROUNDUP(size + PGOFF(la), PGSIZE) / PGSIZE;
+    la = ROUNDDOWN(la, PGSIZE);
+    pa = ROUNDDOWN(pa, PGSIZE);
+    for (; n > 0; n --, la += PGSIZE, pa += PGSIZE) {
+        pte_t *ptep = get_pte(pgdir, la, 1);
+        assert(ptep != NULL);
+        *ptep = pa | PTE_P | perm;
+    }
+}
+
+//boot_alloc_page - allocate one page using pmm->alloc_pages(1) 
+// return value: the kernel virtual address of this allocated page
+//note: this function is used to get the memory for PDT(Page Directory Table)&PT(Page Table)
+static void *
+boot_alloc_page(void) {
+    struct Page *p = alloc_page();
+    if (p == NULL) {
+        panic("boot_alloc_page failed.\n");
+    }
+    return page2kva(p);
+}
+
+//pmm_init - setup a pmm to manage physical memory, build PDT&PT to setup paging mechanism 
+//         - check the correctness of pmm & paging mechanism, print PDT&PT
+void
+pmm_init(void) {
+    //We need to alloc/free the physical memory (granularity is 4KB or other size). 
+    //So a framework of physical memory manager (struct pmm_manager)is defined in pmm.h
+    //First we should init a physical memory manager(pmm) based on the framework.
+    //Then pmm can alloc/free the physical memory. 
+    //Now the first_fit/best_fit/worst_fit/buddy_system pmm are available.
+    init_pmm_manager();
+
+    // detect physical memory space, reserve already used memory,
+    // then use pmm->init_memmap to create free page list
+    page_init();
+
+    //use pmm->check to verify the correctness of the alloc/free function in a pmm
+    check_alloc_page();
+
+    // create boot_pgdir, an initial page directory(Page Directory Table, PDT)
+    boot_pgdir = boot_alloc_page();
+    memset(boot_pgdir, 0, PGSIZE);
+    boot_cr3 = PADDR(boot_pgdir);
+
+    check_pgdir();
+
+    static_assert(KERNBASE % PTSIZE == 0 && KERNTOP % PTSIZE == 0);
+
+    // recursively insert boot_pgdir in itself
+    // to form a virtual page table at virtual address VPT
+    boot_pgdir[PDX(VPT)] = PADDR(boot_pgdir) | PTE_P | PTE_W;
+
+    // map all physical memory to linear memory with base linear addr KERNBASE
+    //linear_addr KERNBASE~KERNBASE+KMEMSIZE = phy_addr 0~KMEMSIZE
+    //But shouldn't use this map until enable_paging() & gdt_init() finished.
+    boot_map_segment(boot_pgdir, KERNBASE, KMEMSIZE, 0, PTE_W);
+
+    //temporary map: 
+    //virtual_addr 3G~3G+4M = linear_addr 0~4M = linear_addr 3G~3G+4M = phy_addr 0~4M     
+    boot_pgdir[0] = boot_pgdir[PDX(KERNBASE)];
+
+    enable_paging();
+
+    //reload gdt(third time,the last time) to map all physical memory
+    //virtual_addr 0~4G=liear_addr 0~4G
+    //then set kernel stack(ss:esp) in TSS, setup TSS in gdt, load TSS
+    gdt_init();
+
+    //disable the map of virtual_addr 0~4M
+    boot_pgdir[0] = 0;
+
+    //now the basic virtual memory map(see memalyout.h) is established.
+    //check the correctness of the basic virtual memory map.
+    check_boot_pgdir();
+
+    print_pgdir();
+    
+    kmalloc_init();
+
+}
+
+//get_pte - get pte and return the kernel virtual address of this pte for la
+//        - if the PT contians this pte didn't exist, alloc a page for PT
+// parameter:
+//  pgdir:  the kernel virtual base address of PDT
+//  la:     the linear address need to map
+//  create: a logical value to decide if alloc a page for PT
+// return vaule: the kernel virtual address of this pte
+pte_t *
+get_pte(pde_t *pgdir, uintptr_t la, bool create) {
+    /* LAB2 EXERCISE 2: YOUR CODE
+     *
+     * If you need to visit a physical address, please use KADDR()
+     * please read pmm.h for useful macros
+     *
+     * Maybe you want help comment, BELOW comments can help you finish the code
+     *
+     * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+     * MACROs or Functions:
+     *   PDX(la) = the index of page directory entry of VIRTUAL ADDRESS la.
+     *   KADDR(pa) : takes a physical address and returns the corresponding kernel virtual address.
+     *   set_page_ref(page,1) : means the page be referenced by one time
+     *   page2pa(page): get the physical address of memory which this (struct Page *) page  manages
+     *   struct Page * alloc_page() : allocation a page
+     *   memset(void *s, char c, size_t n) : sets the first n bytes of the memory area pointed by s
+     *                                       to the specified value c.
+     * DEFINEs:
+     *   PTE_P           0x001                   // page table/directory entry flags bit : Present
+     *   PTE_W           0x002                   // page table/directory entry flags bit : Writeable
+     *   PTE_U           0x004                   // page table/directory entry flags bit : User can access
+     */
+#if 0
+    pde_t *pdep = NULL;   // (1) find page directory entry
+    if (0) {              // (2) check if entry is not present
+                          // (3) check if creating is needed, then alloc page for page table
+                          // CAUTION: this page is used for page table, not for common data page
+                          // (4) set page reference
+        uintptr_t pa = 0; // (5) get linear address of page
+                          // (6) clear page content using memset
+                          // (7) set page directory entry's permission
+    }
+    return NULL;          // (8) return page table entry
+#endif
+    pde_t *pdep = &pgdir[PDX(la)];
+    if (!(*pdep & PTE_P)) {
+        struct Page *page;
+        if (!create || (page = alloc_page()) == NULL) {
+            return NULL;
+        }
+        set_page_ref(page, 1);
+        uintptr_t pa = page2pa(page);
+        memset(KADDR(pa), 0, PGSIZE);
+        *pdep = pa | PTE_U | PTE_W | PTE_P;
+    }
+    return &((pte_t *)KADDR(PDE_ADDR(*pdep)))[PTX(la)];
+}
+
+//get_page - get related Page struct for linear address la using PDT pgdir
+struct Page *
+get_page(pde_t *pgdir, uintptr_t la, pte_t **ptep_store) {
+    pte_t *ptep = get_pte(pgdir, la, 0);
+    if (ptep_store != NULL) {
+        *ptep_store = ptep;
+    }
+    if (ptep != NULL && *ptep & PTE_P) {
+        return pa2page(*ptep);
+    }
+    return NULL;
+}
+
+//page_remove_pte - free an Page sturct which is related linear address la
+//                - and clean(invalidate) pte which is related linear address la
+//note: PT is changed, so the TLB need to be invalidate 
+static inline void
+page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
+    /* LAB2 EXERCISE 3: YOUR CODE
+     *
+     * Please check if ptep is valid, and tlb must be manually updated if mapping is updated
+     *
+     * Maybe you want help comment, BELOW comments can help you finish the code
+     *
+     * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+     * MACROs or Functions:
+     *   struct Page *page pte2page(*ptep): get the according page from the value of a ptep
+     *   free_page : free a page
+     *   page_ref_dec(page) : decrease page->ref. NOTICE: ff page->ref == 0 , then this page should be free.
+     *   tlb_invalidate(pde_t *pgdir, uintptr_t la) : Invalidate a TLB entry, but only if the page tables being
+     *                        edited are the ones currently in use by the processor.
+     * DEFINEs:
+     *   PTE_P           0x001                   // page table/directory entry flags bit : Present
+     */
+#if 0
+    if (0) {                      //(1) check if page directory is present
+        struct Page *page = NULL; //(2) find corresponding page to pte
+                                  //(3) decrease page reference
+                                  //(4) and free this page when page reference reachs 0
+                                  //(5) clear second page table entry
+                                  //(6) flush tlb
+    }
+#endif
+    if (*ptep & PTE_P) {
+        struct Page *page = pte2page(*ptep);
+        if (page_ref_dec(page) == 0) {
+            free_page(page);
+        }
+        *ptep = 0;
+        tlb_invalidate(pgdir, la);
+    }
+}
+
+void
+unmap_range(pde_t *pgdir, uintptr_t start, uintptr_t end) {
+    assert(start % PGSIZE == 0 && end % PGSIZE == 0);
+    assert(USER_ACCESS(start, end));
+
+    do {
+        pte_t *ptep = get_pte(pgdir, start, 0);
+        if (ptep == NULL) {
+            start = ROUNDDOWN(start + PTSIZE, PTSIZE);
+            continue ;
+        }
+        if (*ptep != 0) {
+            page_remove_pte(pgdir, start, ptep);
+        }
+        start += PGSIZE;
+    } while (start != 0 && start < end);
+}
+
+void
+exit_range(pde_t *pgdir, uintptr_t start, uintptr_t end) {
+    assert(start % PGSIZE == 0 && end % PGSIZE == 0);
+    assert(USER_ACCESS(start, end));
+
+    start = ROUNDDOWN(start, PTSIZE);
+    do {
+        int pde_idx = PDX(start);
+        if (pgdir[pde_idx] & PTE_P) {
+            free_page(pde2page(pgdir[pde_idx]));
+            pgdir[pde_idx] = 0;
+        }
+        start += PTSIZE;
+    } while (start != 0 && start < end);
+}
+/* copy_range - copy content of memory (start, end) of one process A to another process B
+ * @to:    the addr of process B's Page Directory
+ * @from:  the addr of process A's Page Directory
+ * @share: flags to indicate to dup OR share. We just use dup method, so it didn't be used.
+ *
+ * CALL GRAPH: copy_mm-->dup_mmap-->copy_range
+ */
+int
+copy_range(pde_t *to, pde_t *from, uintptr_t start, uintptr_t end, bool share) {
+    assert(start % PGSIZE == 0 && end % PGSIZE == 0);
+    assert(USER_ACCESS(start, end));
+    // copy content by page unit.
+    do {
+        //call get_pte to find process A's pte according to the addr start
+        pte_t *ptep = get_pte(from, start, 0), *nptep;
+        if (ptep == NULL) {
+            start = ROUNDDOWN(start + PTSIZE, PTSIZE);
+            continue ;
+        }
+        //call get_pte to find process B's pte according to the addr start. If pte is NULL, just alloc a PT
+        if (*ptep & PTE_P) {
+            if ((nptep = get_pte(to, start, 1)) == NULL) {
+                return -E_NO_MEM;
+            }
+        uint32_t perm = (*ptep & PTE_USER);
+        //get page from ptep
+        struct Page *page = pte2page(*ptep);
+        // alloc a page for process B
+        struct Page *npage=alloc_page();
+        assert(page!=NULL);
+        assert(npage!=NULL);
+        int ret=0;
+        /* LAB5:EXERCISE2 YOUR CODE
+         * replicate content of page to npage, build the map of phy addr of nage with the linear addr start
+         *
+         * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+         * MACROs or Functions:
+         *    page2kva(struct Page *page): return the kernel vritual addr of memory which page managed (SEE pmm.h)
+         *    page_insert: build the map of phy addr of an Page with the linear addr la
+         *    memcpy: typical memory copy function
+         *
+         * (1) find src_kvaddr: the kernel virtual address of page
+         * (2) find dst_kvaddr: the kernel virtual address of npage
+         * (3) memory copy from src_kvaddr to dst_kvaddr, size is PGSIZE
+         * (4) build the map of phy addr of  nage with the linear addr start
+         */
+        void * kva_src = page2kva(page);
+        void * kva_dst = page2kva(npage);
+    
+        memcpy(kva_dst, kva_src, PGSIZE);
+
+        ret = page_insert(to, npage, start, perm);
+        assert(ret == 0);
+        }
+        start += PGSIZE;
+    } while (start != 0 && start < end);
+    return 0;
+}
+
+//page_remove - free an Page which is related linear address la and has an validated pte
+void
+page_remove(pde_t *pgdir, uintptr_t la) {
+    pte_t *ptep = get_pte(pgdir, la, 0);
+    if (ptep != NULL) {
+        page_remove_pte(pgdir, la, ptep);
+    }
+}
+
+//page_insert - build the map of phy addr of an Page with the linear addr la
+// paramemters:
+//  pgdir: the kernel virtual base address of PDT
+//  page:  the Page which need to map
+//  la:    the linear address need to map
+//  perm:  the permission of this Page which is setted in related pte
+// return value: always 0
+//note: PT is changed, so the TLB need to be invalidate 
+int
+page_insert(pde_t *pgdir, struct Page *page, uintptr_t la, uint32_t perm) {
+    pte_t *ptep = get_pte(pgdir, la, 1);
+    if (ptep == NULL) {
+        return -E_NO_MEM;
+    }
+    page_ref_inc(page);
+    if (*ptep & PTE_P) {
+        struct Page *p = pte2page(*ptep);
+        if (p == page) {
+            page_ref_dec(page);
+        }
+        else {
+            page_remove_pte(pgdir, la, ptep);
+        }
+    }
+    *ptep = page2pa(page) | PTE_P | perm;
+    tlb_invalidate(pgdir, la);
+    return 0;
+}
+
+// invalidate a TLB entry, but only if the page tables being
+// edited are the ones currently in use by the processor.
+void
+tlb_invalidate(pde_t *pgdir, uintptr_t la) {
+    if (rcr3() == PADDR(pgdir)) {
+        invlpg((void *)la);
+    }
+}
+
+// pgdir_alloc_page - call alloc_page & page_insert functions to 
+//                  - allocate a page size memory & setup an addr map
+//                  - pa<->la with linear address la and the PDT pgdir
+struct Page *
+pgdir_alloc_page(pde_t *pgdir, uintptr_t la, uint32_t perm) {
+    struct Page *page = alloc_page();
+    if (page != NULL) {
+        if (page_insert(pgdir, page, la, perm) != 0) {
+            free_page(page);
+            return NULL;
+        }
+        if (swap_init_ok){
+            if(check_mm_struct!=NULL) {
+                swap_map_swappable(check_mm_struct, la, page, 0);
+                page->pra_vaddr=la;
+                assert(page_ref(page) == 1);
+                //cprintf("get No. %d  page: pra_vaddr %x, pra_link.prev %x, pra_link_next %x in pgdir_alloc_page\n", (page-pages), page->pra_vaddr,page->pra_page_link.prev, page->pra_page_link.next);
+            } 
+            else  {  //now current is existed, should fix it in the future
+                //swap_map_swappable(current->mm, la, page, 0);
+                //page->pra_vaddr=la;
+                //assert(page_ref(page) == 1);
+                //panic("pgdir_alloc_page: no pages. now current is existed, should fix it in the future\n");
+            }
+        }
+
+    }
+
+    return page;
+}
+
+static void
+check_alloc_page(void) {
+    pmm_manager->check();
+    cprintf("check_alloc_page() succeeded!\n");
+}
+
+static void
+check_pgdir(void) {
+    assert(npage <= KMEMSIZE / PGSIZE);
+    assert(boot_pgdir != NULL && (uint32_t)PGOFF(boot_pgdir) == 0);
+    assert(get_page(boot_pgdir, 0x0, NULL) == NULL);
+
+    struct Page *p1, *p2;
+    p1 = alloc_page();
+    assert(page_insert(boot_pgdir, p1, 0x0, 0) == 0);
+
+    pte_t *ptep;
+    assert((ptep = get_pte(boot_pgdir, 0x0, 0)) != NULL);
+    assert(pa2page(*ptep) == p1);
+    assert(page_ref(p1) == 1);
+
+    ptep = &((pte_t *)KADDR(PDE_ADDR(boot_pgdir[0])))[1];
+    assert(get_pte(boot_pgdir, PGSIZE, 0) == ptep);
+
+    p2 = alloc_page();
+    assert(page_insert(boot_pgdir, p2, PGSIZE, PTE_U | PTE_W) == 0);
+    assert((ptep = get_pte(boot_pgdir, PGSIZE, 0)) != NULL);
+    assert(*ptep & PTE_U);
+    assert(*ptep & PTE_W);
+    assert(boot_pgdir[0] & PTE_U);
+    assert(page_ref(p2) == 1);
+
+    assert(page_insert(boot_pgdir, p1, PGSIZE, 0) == 0);
+    assert(page_ref(p1) == 2);
+    assert(page_ref(p2) == 0);
+    assert((ptep = get_pte(boot_pgdir, PGSIZE, 0)) != NULL);
+    assert(pa2page(*ptep) == p1);
+    assert((*ptep & PTE_U) == 0);
+
+    page_remove(boot_pgdir, 0x0);
+    assert(page_ref(p1) == 1);
+    assert(page_ref(p2) == 0);
+
+    page_remove(boot_pgdir, PGSIZE);
+    assert(page_ref(p1) == 0);
+    assert(page_ref(p2) == 0);
+
+    assert(page_ref(pa2page(boot_pgdir[0])) == 1);
+    free_page(pa2page(boot_pgdir[0]));
+    boot_pgdir[0] = 0;
+
+    cprintf("check_pgdir() succeeded!\n");
+}
+
+static void
+check_boot_pgdir(void) {
+    pte_t *ptep;
+    int i;
+    for (i = 0; i < npage; i += PGSIZE) {
+        assert((ptep = get_pte(boot_pgdir, (uintptr_t)KADDR(i), 0)) != NULL);
+        assert(PTE_ADDR(*ptep) == i);
+    }
+
+    assert(PDE_ADDR(boot_pgdir[PDX(VPT)]) == PADDR(boot_pgdir));
+
+    assert(boot_pgdir[0] == 0);
+
+    struct Page *p;
+    p = alloc_page();
+    assert(page_insert(boot_pgdir, p, 0x100, PTE_W) == 0);
+    assert(page_ref(p) == 1);
+    assert(page_insert(boot_pgdir, p, 0x100 + PGSIZE, PTE_W) == 0);
+    assert(page_ref(p) == 2);
+
+    const char *str = "ucore: Hello world!!";
+    strcpy((void *)0x100, str);
+    assert(strcmp((void *)0x100, (void *)(0x100 + PGSIZE)) == 0);
+
+    *(char *)(page2kva(p) + 0x100) = '\0';
+    assert(strlen((const char *)0x100) == 0);
+
+    free_page(p);
+    free_page(pa2page(PDE_ADDR(boot_pgdir[0])));
+    boot_pgdir[0] = 0;
+
+    cprintf("check_boot_pgdir() succeeded!\n");
+}
+
+//perm2str - use string 'u,r,w,-' to present the permission
+static const char *
+perm2str(int perm) {
+    static char str[4];
+    str[0] = (perm & PTE_U) ? 'u' : '-';
+    str[1] = 'r';
+    str[2] = (perm & PTE_W) ? 'w' : '-';
+    str[3] = '\0';
+    return str;
+}
+
+//get_pgtable_items - In [left, right] range of PDT or PT, find a continuous linear addr space
+//                  - (left_store*X_SIZE~right_store*X_SIZE) for PDT or PT
+//                  - X_SIZE=PTSIZE=4M, if PDT; X_SIZE=PGSIZE=4K, if PT
+// paramemters:
+//  left:        no use ???
+//  right:       the high side of table's range
+//  start:       the low side of table's range
+//  table:       the beginning addr of table
+//  left_store:  the pointer of the high side of table's next range
+//  right_store: the pointer of the low side of table's next range
+// return value: 0 - not a invalid item range, perm - a valid item range with perm permission 
+static int
+get_pgtable_items(size_t left, size_t right, size_t start, uintptr_t *table, size_t *left_store, size_t *right_store) {
+    if (start >= right) {
+        return 0;
+    }
+    while (start < right && !(table[start] & PTE_P)) {
+        start ++;
+    }
+    if (start < right) {
+        if (left_store != NULL) {
+            *left_store = start;
+        }
+        int perm = (table[start ++] & PTE_USER);
+        while (start < right && (table[start] & PTE_USER) == perm) {
+            start ++;
+        }
+        if (right_store != NULL) {
+            *right_store = start;
+        }
+        return perm;
+    }
+    return 0;
+}
+
+//print_pgdir - print the PDT&PT
+void
+print_pgdir(void) {
+    cprintf("-------------------- BEGIN --------------------\n");
+    size_t left, right = 0, perm;
+    while ((perm = get_pgtable_items(0, NPDEENTRY, right, vpd, &left, &right)) != 0) {
+        cprintf("PDE(%03x) %08x-%08x %08x %s\n", right - left,
+                left * PTSIZE, right * PTSIZE, (right - left) * PTSIZE, perm2str(perm));
+        size_t l, r = left * NPTEENTRY;
+        while ((perm = get_pgtable_items(left * NPTEENTRY, right * NPTEENTRY, r, vpt, &l, &r)) != 0) {
+            cprintf("  |-- PTE(%05x) %08x-%08x %08x %s\n", r - l,
+                    l * PGSIZE, r * PGSIZE, (r - l) * PGSIZE, perm2str(perm));
+        }
+    }
+    cprintf("--------------------- END ---------------------\n");
+}
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.h
new file mode 100644
index 0000000..c9470fe
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/pmm.h
@@ -0,0 +1,147 @@
+#ifndef __KERN_MM_PMM_H__
+#define __KERN_MM_PMM_H__
+
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <atomic.h>
+#include <assert.h>
+
+// pmm_manager is a physical memory management class. A special pmm manager - XXX_pmm_manager
+// only needs to implement the methods in pmm_manager class, then XXX_pmm_manager can be used
+// by ucore to manage the total physical memory space.
+struct pmm_manager {
+    const char *name;                                 // XXX_pmm_manager's name
+    void (*init)(void);                               // initialize internal description&management data structure
+                                                      // (free block list, number of free block) of XXX_pmm_manager 
+    void (*init_memmap)(struct Page *base, size_t n); // setup description&management data structcure according to
+                                                      // the initial free physical memory space 
+    struct Page *(*alloc_pages)(size_t n);            // allocate >=n pages, depend on the allocation algorithm 
+    void (*free_pages)(struct Page *base, size_t n);  // free >=n pages with "base" addr of Page descriptor structures(memlayout.h)
+    size_t (*nr_free_pages)(void);                    // return the number of free pages 
+    void (*check)(void);                              // check the correctness of XXX_pmm_manager 
+};
+
+extern const struct pmm_manager *pmm_manager;
+extern pde_t *boot_pgdir;
+extern uintptr_t boot_cr3;
+
+void pmm_init(void);
+
+struct Page *alloc_pages(size_t n);
+void free_pages(struct Page *base, size_t n);
+size_t nr_free_pages(void);
+
+#define alloc_page() alloc_pages(1)
+#define free_page(page) free_pages(page, 1)
+
+pte_t *get_pte(pde_t *pgdir, uintptr_t la, bool create);
+struct Page *get_page(pde_t *pgdir, uintptr_t la, pte_t **ptep_store);
+void page_remove(pde_t *pgdir, uintptr_t la);
+int page_insert(pde_t *pgdir, struct Page *page, uintptr_t la, uint32_t perm);
+
+void load_esp0(uintptr_t esp0);
+void tlb_invalidate(pde_t *pgdir, uintptr_t la);
+struct Page *pgdir_alloc_page(pde_t *pgdir, uintptr_t la, uint32_t perm);
+void unmap_range(pde_t *pgdir, uintptr_t start, uintptr_t end);
+void exit_range(pde_t *pgdir, uintptr_t start, uintptr_t end);
+int copy_range(pde_t *to, pde_t *from, uintptr_t start, uintptr_t end, bool share);
+
+void print_pgdir(void);
+
+/* *
+ * PADDR - takes a kernel virtual address (an address that points above KERNBASE),
+ * where the machine's maximum 256MB of physical memory is mapped and returns the
+ * corresponding physical address.  It panics if you pass it a non-kernel virtual address.
+ * */
+#define PADDR(kva) ({                                                   \
+            uintptr_t __m_kva = (uintptr_t)(kva);                       \
+            if (__m_kva < KERNBASE) {                                   \
+                panic("PADDR called with invalid kva %08lx", __m_kva);  \
+            }                                                           \
+            __m_kva - KERNBASE;                                         \
+        })
+
+/* *
+ * KADDR - takes a physical address and returns the corresponding kernel virtual
+ * address. It panics if you pass an invalid physical address.
+ * */
+#define KADDR(pa) ({                                                    \
+            uintptr_t __m_pa = (pa);                                    \
+            size_t __m_ppn = PPN(__m_pa);                               \
+            if (__m_ppn >= npage) {                                     \
+                panic("KADDR called with invalid pa %08lx", __m_pa);    \
+            }                                                           \
+            (void *) (__m_pa + KERNBASE);                               \
+        })
+
+extern struct Page *pages;
+extern size_t npage;
+
+static inline ppn_t
+page2ppn(struct Page *page) {
+    return page - pages;
+}
+
+static inline uintptr_t
+page2pa(struct Page *page) {
+    return page2ppn(page) << PGSHIFT;
+}
+
+static inline struct Page *
+pa2page(uintptr_t pa) {
+    if (PPN(pa) >= npage) {
+        panic("pa2page called with invalid pa");
+    }
+    return &pages[PPN(pa)];
+}
+
+static inline void *
+page2kva(struct Page *page) {
+    return KADDR(page2pa(page));
+}
+
+static inline struct Page *
+kva2page(void *kva) {
+    return pa2page(PADDR(kva));
+}
+
+static inline struct Page *
+pte2page(pte_t pte) {
+    if (!(pte & PTE_P)) {
+        panic("pte2page called with invalid pte");
+    }
+    return pa2page(PTE_ADDR(pte));
+}
+
+static inline struct Page *
+pde2page(pde_t pde) {
+    return pa2page(PDE_ADDR(pde));
+}
+
+static inline int
+page_ref(struct Page *page) {
+    return page->ref;
+}
+
+static inline void
+set_page_ref(struct Page *page, int val) {
+    page->ref = val;
+}
+
+static inline int
+page_ref_inc(struct Page *page) {
+    page->ref += 1;
+    return page->ref;
+}
+
+static inline int
+page_ref_dec(struct Page *page) {
+    page->ref -= 1;
+    return page->ref;
+}
+
+extern char bootstack[], bootstacktop[];
+
+#endif /* !__KERN_MM_PMM_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.c
new file mode 100644
index 0000000..d2b5952
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.c
@@ -0,0 +1,284 @@
+#include <swap.h>
+#include <swapfs.h>
+#include <swap_fifo.h>
+#include <stdio.h>
+#include <string.h>
+#include <memlayout.h>
+#include <pmm.h>
+#include <mmu.h>
+#include <default_pmm.h>
+#include <kdebug.h>
+
+// the valid vaddr for check is between 0~CHECK_VALID_VADDR-1
+#define CHECK_VALID_VIR_PAGE_NUM 5
+#define BEING_CHECK_VALID_VADDR 0X1000
+#define CHECK_VALID_VADDR (CHECK_VALID_VIR_PAGE_NUM+1)*0x1000
+// the max number of valid physical page for check
+#define CHECK_VALID_PHY_PAGE_NUM 4
+// the max access seq number
+#define MAX_SEQ_NO 10
+
+static struct swap_manager *sm;
+size_t max_swap_offset;
+
+volatile int swap_init_ok = 0;
+
+unsigned int swap_page[CHECK_VALID_VIR_PAGE_NUM];
+
+unsigned int swap_in_seq_no[MAX_SEQ_NO],swap_out_seq_no[MAX_SEQ_NO];
+
+static void check_swap(void);
+
+int
+swap_init(void)
+{
+     swapfs_init();
+
+     if (!(1024 <= max_swap_offset && max_swap_offset < MAX_SWAP_OFFSET_LIMIT))
+     {
+          panic("bad max_swap_offset %08x.\n", max_swap_offset);
+     }
+     
+
+     sm = &swap_manager_fifo;
+     int r = sm->init();
+     
+     if (r == 0)
+     {
+          swap_init_ok = 1;
+          cprintf("SWAP: manager = %s\n", sm->name);
+          check_swap();
+     }
+
+     return r;
+}
+
+int
+swap_init_mm(struct mm_struct *mm)
+{
+     return sm->init_mm(mm);
+}
+
+int
+swap_tick_event(struct mm_struct *mm)
+{
+     return sm->tick_event(mm);
+}
+
+int
+swap_map_swappable(struct mm_struct *mm, uintptr_t addr, struct Page *page, int swap_in)
+{
+     return sm->map_swappable(mm, addr, page, swap_in);
+}
+
+int
+swap_set_unswappable(struct mm_struct *mm, uintptr_t addr)
+{
+     return sm->set_unswappable(mm, addr);
+}
+
+volatile unsigned int swap_out_num=0;
+
+int
+swap_out(struct mm_struct *mm, int n, int in_tick)
+{
+     int i;
+     for (i = 0; i != n; ++ i)
+     {
+          uintptr_t v;
+          //struct Page **ptr_page=NULL;
+          struct Page *page;
+          // cprintf("i %d, SWAP: call swap_out_victim\n",i);
+          int r = sm->swap_out_victim(mm, &page, in_tick);
+          if (r != 0) {
+                    cprintf("i %d, swap_out: call swap_out_victim failed\n",i);
+                  break;
+          }          
+          //assert(!PageReserved(page));
+
+          //cprintf("SWAP: choose victim page 0x%08x\n", page);
+          
+          v=page->pra_vaddr; 
+          pte_t *ptep = get_pte(mm->pgdir, v, 0);
+          assert((*ptep & PTE_P) != 0);
+
+          if (swapfs_write( (page->pra_vaddr/PGSIZE+1)<<8, page) != 0) {
+                    cprintf("SWAP: failed to save\n");
+                    sm->map_swappable(mm, v, page, 0);
+                    continue;
+          }
+          else {
+                    cprintf("swap_out: i %d, store page in vaddr 0x%x to disk swap entry %d\n", i, v, page->pra_vaddr/PGSIZE+1);
+                    *ptep = (page->pra_vaddr/PGSIZE+1)<<8;
+                    free_page(page);
+          }
+          
+          tlb_invalidate(mm->pgdir, v);
+     }
+     return i;
+}
+
+int
+swap_in(struct mm_struct *mm, uintptr_t addr, struct Page **ptr_result)
+{
+     struct Page *result = alloc_page();
+     assert(result!=NULL);
+
+     pte_t *ptep = get_pte(mm->pgdir, addr, 0);
+     // cprintf("SWAP: load ptep %x swap entry %d to vaddr 0x%08x, page %x, No %d\n", ptep, (*ptep)>>8, addr, result, (result-pages));
+    
+     int r;
+     if ((r = swapfs_read((*ptep), result)) != 0)
+     {
+        assert(r!=0);
+     }
+     cprintf("swap_in: load disk swap entry %d with swap_page in vadr 0x%x\n", (*ptep)>>8, addr);
+     *ptr_result=result;
+     return 0;
+}
+
+
+
+static inline void
+check_content_set(void)
+{
+     *(unsigned char *)0x1000 = 0x0a;
+     assert(pgfault_num==1);
+     *(unsigned char *)0x1010 = 0x0a;
+     assert(pgfault_num==1);
+     *(unsigned char *)0x2000 = 0x0b;
+     assert(pgfault_num==2);
+     *(unsigned char *)0x2010 = 0x0b;
+     assert(pgfault_num==2);
+     *(unsigned char *)0x3000 = 0x0c;
+     assert(pgfault_num==3);
+     *(unsigned char *)0x3010 = 0x0c;
+     assert(pgfault_num==3);
+     *(unsigned char *)0x4000 = 0x0d;
+     assert(pgfault_num==4);
+     *(unsigned char *)0x4010 = 0x0d;
+     assert(pgfault_num==4);
+}
+
+static inline int
+check_content_access(void)
+{
+    int ret = sm->check_swap();
+    return ret;
+}
+
+struct Page * check_rp[CHECK_VALID_PHY_PAGE_NUM];
+pte_t * check_ptep[CHECK_VALID_PHY_PAGE_NUM];
+unsigned int check_swap_addr[CHECK_VALID_VIR_PAGE_NUM];
+
+extern free_area_t free_area;
+
+#define free_list (free_area.free_list)
+#define nr_free (free_area.nr_free)
+
+static void
+check_swap(void)
+{
+    //backup mem env
+     int ret, count = 0, total = 0, i;
+     list_entry_t *le = &free_list;
+     while ((le = list_next(le)) != &free_list) {
+        struct Page *p = le2page(le, page_link);
+        assert(PageProperty(p));
+        count ++, total += p->property;
+     }
+     assert(total == nr_free_pages());
+     cprintf("BEGIN check_swap: count %d, total %d\n",count,total);
+     
+     //now we set the phy pages env     
+     struct mm_struct *mm = mm_create();
+     assert(mm != NULL);
+
+     extern struct mm_struct *check_mm_struct;
+     assert(check_mm_struct == NULL);
+
+     check_mm_struct = mm;
+
+     pde_t *pgdir = mm->pgdir = boot_pgdir;
+     assert(pgdir[0] == 0);
+
+     struct vma_struct *vma = vma_create(BEING_CHECK_VALID_VADDR, CHECK_VALID_VADDR, VM_WRITE | VM_READ);
+     assert(vma != NULL);
+
+     insert_vma_struct(mm, vma);
+
+     //setup the temp Page Table vaddr 0~4MB
+     cprintf("setup Page Table for vaddr 0X1000, so alloc a page\n");
+     pte_t *temp_ptep=NULL;
+     temp_ptep = get_pte(mm->pgdir, BEING_CHECK_VALID_VADDR, 1);
+     assert(temp_ptep!= NULL);
+     cprintf("setup Page Table vaddr 0~4MB OVER!\n");
+     
+     for (i=0;i<CHECK_VALID_PHY_PAGE_NUM;i++) {
+          check_rp[i] = alloc_page();
+          assert(check_rp[i] != NULL );
+          assert(!PageProperty(check_rp[i]));
+     }
+     list_entry_t free_list_store = free_list;
+     list_init(&free_list);
+     assert(list_empty(&free_list));
+     
+     //assert(alloc_page() == NULL);
+     
+     unsigned int nr_free_store = nr_free;
+     nr_free = 0;
+     for (i=0;i<CHECK_VALID_PHY_PAGE_NUM;i++) {
+        free_pages(check_rp[i],1);
+     }
+     assert(nr_free==CHECK_VALID_PHY_PAGE_NUM);
+     
+     cprintf("set up init env for check_swap begin!\n");
+     //setup initial vir_page<->phy_page environment for page relpacement algorithm 
+
+     
+     pgfault_num=0;
+     
+     check_content_set();
+     assert( nr_free == 0);         
+     for(i = 0; i<MAX_SEQ_NO ; i++) 
+         swap_out_seq_no[i]=swap_in_seq_no[i]=-1;
+     
+     for (i= 0;i<CHECK_VALID_PHY_PAGE_NUM;i++) {
+         check_ptep[i]=0;
+         check_ptep[i] = get_pte(pgdir, (i+1)*0x1000, 0);
+         //cprintf("i %d, check_ptep addr %x, value %x\n", i, check_ptep[i], *check_ptep[i]);
+         assert(check_ptep[i] != NULL);
+         assert(pte2page(*check_ptep[i]) == check_rp[i]);
+         assert((*check_ptep[i] & PTE_P));          
+     }
+     cprintf("set up init env for check_swap over!\n");
+     // now access the virt pages to test  page relpacement algorithm 
+     ret=check_content_access();
+     assert(ret==0);
+     
+     //restore kernel mem env
+     for (i=0;i<CHECK_VALID_PHY_PAGE_NUM;i++) {
+         free_pages(check_rp[i],1);
+     } 
+
+     //free_page(pte2page(*temp_ptep));
+    free_page(pa2page(pgdir[0]));
+     pgdir[0] = 0;
+     mm->pgdir = NULL;
+     mm_destroy(mm);
+     check_mm_struct = NULL;
+     
+     nr_free = nr_free_store;
+     free_list = free_list_store;
+
+     
+     le = &free_list;
+     while ((le = list_next(le)) != &free_list) {
+         struct Page *p = le2page(le, page_link);
+         count --, total -= p->property;
+     }
+     cprintf("count is %d, total is %d\n",count,total);
+     //assert(count == 0);
+     
+     cprintf("check_swap() succeeded!\n");
+}
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.h
new file mode 100644
index 0000000..5d4aea8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap.h
@@ -0,0 +1,65 @@
+#ifndef __KERN_MM_SWAP_H__
+#define __KERN_MM_SWAP_H__
+
+#include <defs.h>
+#include <memlayout.h>
+#include <pmm.h>
+#include <vmm.h>
+
+/* *
+ * swap_entry_t
+ * --------------------------------------------
+ * |         offset        |   reserved   | 0 |
+ * --------------------------------------------
+ *           24 bits            7 bits    1 bit
+ * */
+
+#define MAX_SWAP_OFFSET_LIMIT                   (1 << 24)
+
+extern size_t max_swap_offset;
+
+/* *
+ * swap_offset - takes a swap_entry (saved in pte), and returns
+ * the corresponding offset in swap mem_map.
+ * */
+#define swap_offset(entry) ({                                       \
+               size_t __offset = (entry >> 8);                        \
+               if (!(__offset > 0 && __offset < max_swap_offset)) {    \
+                    panic("invalid swap_entry_t = %08x.\n", entry);    \
+               }                                                    \
+               __offset;                                            \
+          })
+
+struct swap_manager
+{
+     const char *name;
+     /* Global initialization for the swap manager */
+     int (*init)            (void);
+     /* Initialize the priv data inside mm_struct */
+     int (*init_mm)         (struct mm_struct *mm);
+     /* Called when tick interrupt occured */
+     int (*tick_event)      (struct mm_struct *mm);
+     /* Called when map a swappable page into the mm_struct */
+     int (*map_swappable)   (struct mm_struct *mm, uintptr_t addr, struct Page *page, int swap_in);
+     /* When a page is marked as shared, this routine is called to
+      * delete the addr entry from the swap manager */
+     int (*set_unswappable) (struct mm_struct *mm, uintptr_t addr);
+     /* Try to swap out a page, return then victim */
+     int (*swap_out_victim) (struct mm_struct *mm, struct Page **ptr_page, int in_tick);
+     /* check the page relpacement algorithm */
+     int (*check_swap)(void);     
+};
+
+extern volatile int swap_init_ok;
+int swap_init(void);
+int swap_init_mm(struct mm_struct *mm);
+int swap_tick_event(struct mm_struct *mm);
+int swap_map_swappable(struct mm_struct *mm, uintptr_t addr, struct Page *page, int swap_in);
+int swap_set_unswappable(struct mm_struct *mm, uintptr_t addr);
+int swap_out(struct mm_struct *mm, int n, int in_tick);
+int swap_in(struct mm_struct *mm, uintptr_t addr, struct Page **ptr_result);
+
+//#define MEMBER_OFFSET(m,t) ((int)(&((t *)0)->m))
+//#define FROM_MEMBER(m,t,a) ((t *)((char *)(a) - MEMBER_OFFSET(m,t)))
+
+#endif
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.c
new file mode 100644
index 0000000..ae6caf3
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.c
@@ -0,0 +1,144 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <swap.h>
+#include <swap_fifo.h>
+#include <list.h>
+
+/* [wikipedia]The simplest Page Replacement Algorithm(PRA) is a FIFO algorithm. The first-in, first-out
+ * page replacement algorithm is a low-overhead algorithm that requires little book-keeping on
+ * the part of the operating system. The idea is obvious from the name - the operating system
+ * keeps track of all the pages in memory in a queue, with the most recent arrival at the back,
+ * and the earliest arrival in front. When a page needs to be replaced, the page at the front
+ * of the queue (the oldest page) is selected. While FIFO is cheap and intuitive, it performs
+ * poorly in practical application. Thus, it is rarely used in its unmodified form. This
+ * algorithm experiences Belady's anomaly.
+ *
+ * Details of FIFO PRA
+ * (1) Prepare: In order to implement FIFO PRA, we should manage all swappable pages, so we can
+ *              link these pages into pra_list_head according the time order. At first you should
+ *              be familiar to the struct list in list.h. struct list is a simple doubly linked list
+ *              implementation. You should know howto USE: list_init, list_add(list_add_after),
+ *              list_add_before, list_del, list_next, list_prev. Another tricky method is to transform
+ *              a general list struct to a special struct (such as struct page). You can find some MACRO:
+ *              le2page (in memlayout.h), (in future labs: le2vma (in vmm.h), le2proc (in proc.h),etc.
+ */
+
+list_entry_t pra_list_head;
+/*
+ * (2) _fifo_init_mm: init pra_list_head and let  mm->sm_priv point to the addr of pra_list_head.
+ *              Now, From the memory control struct mm_struct, we can access FIFO PRA
+ */
+static int
+_fifo_init_mm(struct mm_struct *mm)
+{     
+     list_init(&pra_list_head);
+     mm->sm_priv = &pra_list_head;
+     //cprintf(" mm->sm_priv %x in fifo_init_mm\n",mm->sm_priv);
+     return 0;
+}
+/*
+ * (3)_fifo_map_swappable: According FIFO PRA, we should link the most recent arrival page at the back of pra_list_head qeueue
+ */
+static int
+_fifo_map_swappable(struct mm_struct *mm, uintptr_t addr, struct Page *page, int swap_in)
+{
+    list_entry_t *head=(list_entry_t*) mm->sm_priv;
+    list_entry_t *entry=&(page->pra_page_link);
+ 
+    assert(entry != NULL && head != NULL);
+    //record the page access situlation
+    /*LAB3 EXERCISE 2: YOUR CODE*/ 
+    //(1)link the most recent arrival page at the back of the pra_list_head qeueue.
+    list_add(head, entry);
+    return 0;
+}
+/*
+ *  (4)_fifo_swap_out_victim: According FIFO PRA, we should unlink the  earliest arrival page in front of pra_list_head qeueue,
+ *                            then set the addr of addr of this page to ptr_page.
+ */
+static int
+_fifo_swap_out_victim(struct mm_struct *mm, struct Page ** ptr_page, int in_tick)
+{
+     list_entry_t *head=(list_entry_t*) mm->sm_priv;
+         assert(head != NULL);
+     assert(in_tick==0);
+     /* Select the victim */
+     /*LAB3 EXERCISE 2: YOUR CODE*/ 
+     //(1)  unlink the  earliest arrival page in front of pra_list_head qeueue
+     //(2)  set the addr of addr of this page to ptr_page
+     /* Select the tail */
+     list_entry_t *le = head->prev;
+     assert(head!=le);
+     struct Page *p = le2page(le, pra_page_link);
+     list_del(le);
+     assert(p !=NULL);
+     *ptr_page = p;
+     return 0;
+}
+
+static int
+_fifo_check_swap(void) {
+    cprintf("write Virt Page c in fifo_check_swap\n");
+    *(unsigned char *)0x3000 = 0x0c;
+    assert(pgfault_num==4);
+    cprintf("write Virt Page a in fifo_check_swap\n");
+    *(unsigned char *)0x1000 = 0x0a;
+    assert(pgfault_num==4);
+    cprintf("write Virt Page d in fifo_check_swap\n");
+    *(unsigned char *)0x4000 = 0x0d;
+    assert(pgfault_num==4);
+    cprintf("write Virt Page b in fifo_check_swap\n");
+    *(unsigned char *)0x2000 = 0x0b;
+    assert(pgfault_num==4);
+    cprintf("write Virt Page e in fifo_check_swap\n");
+    *(unsigned char *)0x5000 = 0x0e;
+    assert(pgfault_num==5);
+    cprintf("write Virt Page b in fifo_check_swap\n");
+    *(unsigned char *)0x2000 = 0x0b;
+    assert(pgfault_num==5);
+    cprintf("write Virt Page a in fifo_check_swap\n");
+    *(unsigned char *)0x1000 = 0x0a;
+    assert(pgfault_num==6);
+    cprintf("write Virt Page b in fifo_check_swap\n");
+    *(unsigned char *)0x2000 = 0x0b;
+    assert(pgfault_num==7);
+    cprintf("write Virt Page c in fifo_check_swap\n");
+    *(unsigned char *)0x3000 = 0x0c;
+    assert(pgfault_num==8);
+    cprintf("write Virt Page d in fifo_check_swap\n");
+    *(unsigned char *)0x4000 = 0x0d;
+    assert(pgfault_num==9);
+    return 0;
+}
+
+
+static int
+_fifo_init(void)
+{
+    return 0;
+}
+
+static int
+_fifo_set_unswappable(struct mm_struct *mm, uintptr_t addr)
+{
+    return 0;
+}
+
+static int
+_fifo_tick_event(struct mm_struct *mm)
+{ return 0; }
+
+
+struct swap_manager swap_manager_fifo =
+{
+     .name            = "fifo swap manager",
+     .init            = &_fifo_init,
+     .init_mm         = &_fifo_init_mm,
+     .tick_event      = &_fifo_tick_event,
+     .map_swappable   = &_fifo_map_swappable,
+     .set_unswappable = &_fifo_set_unswappable,
+     .swap_out_victim = &_fifo_swap_out_victim,
+     .check_swap      = &_fifo_check_swap,
+};
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.h
new file mode 100644
index 0000000..1d74269
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/swap_fifo.h
@@ -0,0 +1,7 @@
+#ifndef __KERN_MM_SWAP_FIFO_H__
+#define __KERN_MM_SWAP_FIFO_H__
+
+#include <swap.h>
+extern struct swap_manager swap_manager_fifo;
+
+#endif
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.c b/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.c
new file mode 100644
index 0000000..4f4aaed
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.c
@@ -0,0 +1,562 @@
+#include <vmm.h>
+#include <sync.h>
+#include <string.h>
+#include <assert.h>
+#include <stdio.h>
+#include <error.h>
+#include <pmm.h>
+#include <x86.h>
+#include <swap.h>
+#include <kmalloc.h>
+
+/* 
+  vmm design include two parts: mm_struct (mm) & vma_struct (vma)
+  mm is the memory manager for the set of continuous virtual memory  
+  area which have the same PDT. vma is a continuous virtual memory area.
+  There a linear link list for vma & a redblack link list for vma in mm.
+---------------
+  mm related functions:
+   golbal functions
+     struct mm_struct * mm_create(void)
+     void mm_destroy(struct mm_struct *mm)
+     int do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr)
+--------------
+  vma related functions:
+   global functions
+     struct vma_struct * vma_create (uintptr_t vm_start, uintptr_t vm_end,...)
+     void insert_vma_struct(struct mm_struct *mm, struct vma_struct *vma)
+     struct vma_struct * find_vma(struct mm_struct *mm, uintptr_t addr)
+   local functions
+     inline void check_vma_overlap(struct vma_struct *prev, struct vma_struct *next)
+---------------
+   check correctness functions
+     void check_vmm(void);
+     void check_vma_struct(void);
+     void check_pgfault(void);
+*/
+
+static void check_vmm(void);
+static void check_vma_struct(void);
+static void check_pgfault(void);
+
+// mm_create -  alloc a mm_struct & initialize it.
+struct mm_struct *
+mm_create(void) {
+    struct mm_struct *mm = kmalloc(sizeof(struct mm_struct));
+
+    if (mm != NULL) {
+        list_init(&(mm->mmap_list));
+        mm->mmap_cache = NULL;
+        mm->pgdir = NULL;
+        mm->map_count = 0;
+
+        if (swap_init_ok) swap_init_mm(mm);
+        else mm->sm_priv = NULL;
+        
+        set_mm_count(mm, 0);
+        lock_init(&(mm->mm_lock));
+    }    
+    return mm;
+}
+
+// vma_create - alloc a vma_struct & initialize it. (addr range: vm_start~vm_end)
+struct vma_struct *
+vma_create(uintptr_t vm_start, uintptr_t vm_end, uint32_t vm_flags) {
+    struct vma_struct *vma = kmalloc(sizeof(struct vma_struct));
+
+    if (vma != NULL) {
+        vma->vm_start = vm_start;
+        vma->vm_end = vm_end;
+        vma->vm_flags = vm_flags;
+    }
+    return vma;
+}
+
+
+// find_vma - find a vma  (vma->vm_start <= addr <= vma_vm_end)
+struct vma_struct *
+find_vma(struct mm_struct *mm, uintptr_t addr) {
+    struct vma_struct *vma = NULL;
+    if (mm != NULL) {
+        vma = mm->mmap_cache;
+        if (!(vma != NULL && vma->vm_start <= addr && vma->vm_end > addr)) {
+                bool found = 0;
+                list_entry_t *list = &(mm->mmap_list), *le = list;
+                while ((le = list_next(le)) != list) {
+                    vma = le2vma(le, list_link);
+                    if (vma->vm_start<=addr && addr < vma->vm_end) {
+                        found = 1;
+                        break;
+                    }
+                }
+                if (!found) {
+                    vma = NULL;
+                }
+        }
+        if (vma != NULL) {
+            mm->mmap_cache = vma;
+        }
+    }
+    return vma;
+}
+
+
+// check_vma_overlap - check if vma1 overlaps vma2 ?
+static inline void
+check_vma_overlap(struct vma_struct *prev, struct vma_struct *next) {
+    assert(prev->vm_start < prev->vm_end);
+    assert(prev->vm_end <= next->vm_start);
+    assert(next->vm_start < next->vm_end);
+}
+
+
+// insert_vma_struct -insert vma in mm's list link
+void
+insert_vma_struct(struct mm_struct *mm, struct vma_struct *vma) {
+    assert(vma->vm_start < vma->vm_end);
+    list_entry_t *list = &(mm->mmap_list);
+    list_entry_t *le_prev = list, *le_next;
+
+        list_entry_t *le = list;
+        while ((le = list_next(le)) != list) {
+            struct vma_struct *mmap_prev = le2vma(le, list_link);
+            if (mmap_prev->vm_start > vma->vm_start) {
+                break;
+            }
+            le_prev = le;
+        }
+
+    le_next = list_next(le_prev);
+
+    /* check overlap */
+    if (le_prev != list) {
+        check_vma_overlap(le2vma(le_prev, list_link), vma);
+    }
+    if (le_next != list) {
+        check_vma_overlap(vma, le2vma(le_next, list_link));
+    }
+
+    vma->vm_mm = mm;
+    list_add_after(le_prev, &(vma->list_link));
+
+    mm->map_count ++;
+}
+
+// mm_destroy - free mm and mm internal fields
+void
+mm_destroy(struct mm_struct *mm) {
+    assert(mm_count(mm) == 0);
+
+    list_entry_t *list = &(mm->mmap_list), *le;
+    while ((le = list_next(list)) != list) {
+        list_del(le);
+        kfree(le2vma(le, list_link));  //kfree vma        
+    }
+    kfree(mm); //kfree mm
+    mm=NULL;
+}
+
+int
+mm_map(struct mm_struct *mm, uintptr_t addr, size_t len, uint32_t vm_flags,
+       struct vma_struct **vma_store) {
+    uintptr_t start = ROUNDDOWN(addr, PGSIZE), end = ROUNDUP(addr + len, PGSIZE);
+    if (!USER_ACCESS(start, end)) {
+        return -E_INVAL;
+    }
+
+    assert(mm != NULL);
+
+    int ret = -E_INVAL;
+
+    struct vma_struct *vma;
+    if ((vma = find_vma(mm, start)) != NULL && end > vma->vm_start) {
+        goto out;
+    }
+    ret = -E_NO_MEM;
+
+    if ((vma = vma_create(start, end, vm_flags)) == NULL) {
+        goto out;
+    }
+    insert_vma_struct(mm, vma);
+    if (vma_store != NULL) {
+        *vma_store = vma;
+    }
+    ret = 0;
+
+out:
+    return ret;
+}
+
+int
+dup_mmap(struct mm_struct *to, struct mm_struct *from) {
+    assert(to != NULL && from != NULL);
+    list_entry_t *list = &(from->mmap_list), *le = list;
+    while ((le = list_prev(le)) != list) {
+        struct vma_struct *vma, *nvma;
+        vma = le2vma(le, list_link);
+        nvma = vma_create(vma->vm_start, vma->vm_end, vma->vm_flags);
+        if (nvma == NULL) {
+            return -E_NO_MEM;
+        }
+
+        insert_vma_struct(to, nvma);
+
+        bool share = 0;
+        if (copy_range(to->pgdir, from->pgdir, vma->vm_start, vma->vm_end, share) != 0) {
+            return -E_NO_MEM;
+        }
+    }
+    return 0;
+}
+
+void
+exit_mmap(struct mm_struct *mm) {
+    assert(mm != NULL && mm_count(mm) == 0);
+    pde_t *pgdir = mm->pgdir;
+    list_entry_t *list = &(mm->mmap_list), *le = list;
+    while ((le = list_next(le)) != list) {
+        struct vma_struct *vma = le2vma(le, list_link);
+        unmap_range(pgdir, vma->vm_start, vma->vm_end);
+    }
+    while ((le = list_next(le)) != list) {
+        struct vma_struct *vma = le2vma(le, list_link);
+        exit_range(pgdir, vma->vm_start, vma->vm_end);
+    }
+}
+
+bool
+copy_from_user(struct mm_struct *mm, void *dst, const void *src, size_t len, bool writable) {
+    if (!user_mem_check(mm, (uintptr_t)src, len, writable)) {
+        return 0;
+    }
+    memcpy(dst, src, len);
+    return 1;
+}
+
+bool
+copy_to_user(struct mm_struct *mm, void *dst, const void *src, size_t len) {
+    if (!user_mem_check(mm, (uintptr_t)dst, len, 1)) {
+        return 0;
+    }
+    memcpy(dst, src, len);
+    return 1;
+}
+
+// vmm_init - initialize virtual memory management
+//          - now just call check_vmm to check correctness of vmm
+void
+vmm_init(void) {
+    check_vmm();
+}
+
+// check_vmm - check correctness of vmm
+static void
+check_vmm(void) {
+    size_t nr_free_pages_store = nr_free_pages();
+    
+    check_vma_struct();
+    check_pgfault();
+
+//    assert(nr_free_pages_store == nr_free_pages());
+
+    cprintf("check_vmm() succeeded.\n");
+}
+
+static void
+check_vma_struct(void) {
+    size_t nr_free_pages_store = nr_free_pages();
+
+    struct mm_struct *mm = mm_create();
+    assert(mm != NULL);
+
+    int step1 = 10, step2 = step1 * 10;
+
+    int i;
+    for (i = step1; i >= 1; i --) {
+        struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
+        assert(vma != NULL);
+        insert_vma_struct(mm, vma);
+    }
+
+    for (i = step1 + 1; i <= step2; i ++) {
+        struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
+        assert(vma != NULL);
+        insert_vma_struct(mm, vma);
+    }
+
+    list_entry_t *le = list_next(&(mm->mmap_list));
+
+    for (i = 1; i <= step2; i ++) {
+        assert(le != &(mm->mmap_list));
+        struct vma_struct *mmap = le2vma(le, list_link);
+        assert(mmap->vm_start == i * 5 && mmap->vm_end == i * 5 + 2);
+        le = list_next(le);
+    }
+
+    for (i = 5; i <= 5 * step2; i +=5) {
+        struct vma_struct *vma1 = find_vma(mm, i);
+        assert(vma1 != NULL);
+        struct vma_struct *vma2 = find_vma(mm, i+1);
+        assert(vma2 != NULL);
+        struct vma_struct *vma3 = find_vma(mm, i+2);
+        assert(vma3 == NULL);
+        struct vma_struct *vma4 = find_vma(mm, i+3);
+        assert(vma4 == NULL);
+        struct vma_struct *vma5 = find_vma(mm, i+4);
+        assert(vma5 == NULL);
+
+        assert(vma1->vm_start == i  && vma1->vm_end == i  + 2);
+        assert(vma2->vm_start == i  && vma2->vm_end == i  + 2);
+    }
+
+    for (i =4; i>=0; i--) {
+        struct vma_struct *vma_below_5= find_vma(mm,i);
+        if (vma_below_5 != NULL ) {
+           cprintf("vma_below_5: i %x, start %x, end %x\n",i, vma_below_5->vm_start, vma_below_5->vm_end); 
+        }
+        assert(vma_below_5 == NULL);
+    }
+
+    mm_destroy(mm);
+
+//    assert(nr_free_pages_store == nr_free_pages());
+
+    cprintf("check_vma_struct() succeeded!\n");
+}
+
+struct mm_struct *check_mm_struct;
+
+// check_pgfault - check correctness of pgfault handler
+static void
+check_pgfault(void) {
+    size_t nr_free_pages_store = nr_free_pages();
+
+    check_mm_struct = mm_create();
+    assert(check_mm_struct != NULL);
+
+    struct mm_struct *mm = check_mm_struct;
+    pde_t *pgdir = mm->pgdir = boot_pgdir;
+    assert(pgdir[0] == 0);
+
+    struct vma_struct *vma = vma_create(0, PTSIZE, VM_WRITE);
+    assert(vma != NULL);
+
+    insert_vma_struct(mm, vma);
+
+    uintptr_t addr = 0x100;
+    assert(find_vma(mm, addr) == vma);
+
+    int i, sum = 0;
+    for (i = 0; i < 100; i ++) {
+        *(char *)(addr + i) = i;
+        sum += i;
+    }
+    for (i = 0; i < 100; i ++) {
+        sum -= *(char *)(addr + i);
+    }
+    assert(sum == 0);
+
+    page_remove(pgdir, ROUNDDOWN(addr, PGSIZE));
+    free_page(pa2page(pgdir[0]));
+    pgdir[0] = 0;
+
+    mm->pgdir = NULL;
+    mm_destroy(mm);
+    check_mm_struct = NULL;
+
+    assert(nr_free_pages_store == nr_free_pages());
+
+    cprintf("check_pgfault() succeeded!\n");
+}
+//page fault number
+volatile unsigned int pgfault_num=0;
+
+/* do_pgfault - interrupt handler to process the page fault execption
+ * @mm         : the control struct for a set of vma using the same PDT
+ * @error_code : the error code recorded in trapframe->tf_err which is setted by x86 hardware
+ * @addr       : the addr which causes a memory access exception, (the contents of the CR2 register)
+ *
+ * CALL GRAPH: trap--> trap_dispatch-->pgfault_handler-->do_pgfault
+ * The processor provides ucore's do_pgfault function with two items of information to aid in diagnosing
+ * the exception and recovering from it.
+ *   (1) The contents of the CR2 register. The processor loads the CR2 register with the
+ *       32-bit linear address that generated the exception. The do_pgfault fun can
+ *       use this address to locate the corresponding page directory and page-table
+ *       entries.
+ *   (2) An error code on the kernel stack. The error code for a page fault has a format different from
+ *       that for other exceptions. The error code tells the exception handler three things:
+ *         -- The P flag   (bit 0) indicates whether the exception was due to a not-present page (0)
+ *            or to either an access rights violation or the use of a reserved bit (1).
+ *         -- The W/R flag (bit 1) indicates whether the memory access that caused the exception
+ *            was a read (0) or write (1).
+ *         -- The U/S flag (bit 2) indicates whether the processor was executing at user mode (1)
+ *            or supervisor mode (0) at the time of the exception.
+ */
+int
+do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr) {
+    int ret = -E_INVAL;
+    //try to find a vma which include addr
+    struct vma_struct *vma = find_vma(mm, addr);
+
+    pgfault_num++;
+    //If the addr is in the range of a mm's vma?
+    if (vma == NULL || vma->vm_start > addr) {
+        cprintf("not valid addr %x, and  can not find it in vma\n", addr);
+        goto failed;
+    }
+    //check the error_code
+    switch (error_code & 3) {
+    default:
+            /* error code flag : default is 3 ( W/R=1, P=1): write, present */
+    case 2: /* error code flag : (W/R=1, P=0): write, not present */
+        if (!(vma->vm_flags & VM_WRITE)) {
+            cprintf("do_pgfault failed: error code flag = write AND not present, but the addr's vma cannot write\n");
+            goto failed;
+        }
+        break;
+    case 1: /* error code flag : (W/R=0, P=1): read, present */
+        cprintf("do_pgfault failed: error code flag = read AND present\n");
+        goto failed;
+    case 0: /* error code flag : (W/R=0, P=0): read, not present */
+        if (!(vma->vm_flags & (VM_READ | VM_EXEC))) {
+            cprintf("do_pgfault failed: error code flag = read AND not present, but the addr's vma cannot read or exec\n");
+            goto failed;
+        }
+    }
+    /* IF (write an existed addr ) OR
+     *    (write an non_existed addr && addr is writable) OR
+     *    (read  an non_existed addr && addr is readable)
+     * THEN
+     *    continue process
+     */
+    uint32_t perm = PTE_U;
+    if (vma->vm_flags & VM_WRITE) {
+        perm |= PTE_W;
+    }
+    addr = ROUNDDOWN(addr, PGSIZE);
+
+    ret = -E_NO_MEM;
+
+    pte_t *ptep=NULL;
+    /*LAB3 EXERCISE 1: YOUR CODE
+    * Maybe you want help comment, BELOW comments can help you finish the code
+    *
+    * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+    * MACROs or Functions:
+    *   get_pte : get an pte and return the kernel virtual address of this pte for la
+    *             if the PT contians this pte didn't exist, alloc a page for PT (notice the 3th parameter '1')
+    *   pgdir_alloc_page : call alloc_page & page_insert functions to allocate a page size memory & setup
+    *             an addr map pa<--->la with linear address la and the PDT pgdir
+    * DEFINES:
+    *   VM_WRITE  : If vma->vm_flags & VM_WRITE == 1/0, then the vma is writable/non writable
+    *   PTE_W           0x002                   // page table/directory entry flags bit : Writeable
+    *   PTE_U           0x004                   // page table/directory entry flags bit : User can access
+    * VARIABLES:
+    *   mm->pgdir : the PDT of these vma
+    *
+    */
+#if 0
+    /*LAB3 EXERCISE 1: YOUR CODE*/
+    ptep = ???              //(1) try to find a pte, if pte's PT(Page Table) isn't existed, then create a PT.
+    if (*ptep == 0) {
+                            //(2) if the phy addr isn't exist, then alloc a page & map the phy addr with logical addr
+
+    }
+    else {
+    /*LAB3 EXERCISE 2: YOUR CODE
+    * Now we think this pte is a  swap entry, we should load data from disk to a page with phy addr,
+    * and map the phy addr with logical addr, trigger swap manager to record the access situation of this page.
+    *
+    *  Some Useful MACROs and DEFINEs, you can use them in below implementation.
+    *  MACROs or Functions:
+    *    swap_in(mm, addr, &page) : alloc a memory page, then according to the swap entry in PTE for addr,
+    *                               find the addr of disk page, read the content of disk page into this memroy page
+    *    page_insert ： build the map of phy addr of an Page with the linear addr la
+    *    swap_map_swappable ： set the page swappable
+    */
+        if(swap_init_ok) {
+            struct Page *page=NULL;
+                                    //(1）According to the mm AND addr, try to load the content of right disk page
+                                    //    into the memory which page managed.
+                                    //(2) According to the mm, addr AND page, setup the map of phy addr <---> logical addr
+                                    //(3) make the page swappable.
+                                    //(4) [NOTICE]: you myabe need to update your lab3's implementation for LAB5's normal execution.
+        }
+        else {
+            cprintf("no swap_init_ok but ptep is %x, failed\n",*ptep);
+            goto failed;
+        }
+   }
+#endif
+    // try to find a pte, if pte's PT(Page Table) isn't existed, then create a PT.
+    // (notice the 3th parameter '1')
+    if ((ptep = get_pte(mm->pgdir, addr, 1)) == NULL) {
+        cprintf("get_pte in do_pgfault failed\n");
+        goto failed;
+    }
+    
+    if (*ptep == 0) { // if the phy addr isn't exist, then alloc a page & map the phy addr with logical addr
+        if (pgdir_alloc_page(mm->pgdir, addr, perm) == NULL) {
+            cprintf("pgdir_alloc_page in do_pgfault failed\n");
+            goto failed;
+        }
+    }
+    else {
+        struct Page *page=NULL;
+        cprintf("do pgfault: ptep %x, pte %x\n",ptep, *ptep);
+        if (*ptep & PTE_P) {
+            //if process write to this existed readonly page (PTE_P means existed), then should be here now.
+            //we can implement the delayed memory space copy for fork child process (AKA copy on write, COW).
+            //we didn't implement now, we will do it in future.
+            panic("error write a non-writable pte");
+            //page = pte2page(*ptep);
+        } else{
+           // if this pte is a swap entry, then load data from disk to a page with phy addr
+           // and call page_insert to map the phy addr with logical addr
+           if(swap_init_ok) {               
+               if ((ret = swap_in(mm, addr, &page)) != 0) {
+                   cprintf("swap_in in do_pgfault failed\n");
+                   goto failed;
+               }    
+
+           }  
+           else {
+            cprintf("no swap_init_ok but ptep is %x, failed\n",*ptep);
+            goto failed;
+           }
+       } 
+       page_insert(mm->pgdir, page, addr, perm);
+       swap_map_swappable(mm, addr, page, 1);
+   }
+   ret = 0;
+failed:
+    return ret;
+}
+
+bool
+user_mem_check(struct mm_struct *mm, uintptr_t addr, size_t len, bool write) {
+    if (mm != NULL) {
+        if (!USER_ACCESS(addr, addr + len)) {
+            return 0;
+        }
+        struct vma_struct *vma;
+        uintptr_t start = addr, end = addr + len;
+        while (start < end) {
+            if ((vma = find_vma(mm, start)) == NULL || start < vma->vm_start) {
+                return 0;
+            }
+            if (!(vma->vm_flags & ((write) ? VM_WRITE : VM_READ))) {
+                return 0;
+            }
+            if (write && (vma->vm_flags & VM_STACK)) {
+                if (start < vma->vm_start + PGSIZE) { //check stack start & size
+                    return 0;
+                }
+            }
+            start = vma->vm_end;
+        }
+        return 1;
+    }
+    return KERN_ACCESS(addr, addr + len);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.h b/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.h
new file mode 100644
index 0000000..53f98d1
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/mm/vmm.h
@@ -0,0 +1,102 @@
+#ifndef __KERN_MM_VMM_H__
+#define __KERN_MM_VMM_H__
+
+#include <defs.h>
+#include <list.h>
+#include <memlayout.h>
+#include <sync.h>
+
+//pre define
+struct mm_struct;
+
+// the virtual continuous memory area(vma)
+struct vma_struct {
+    struct mm_struct *vm_mm; // the set of vma using the same PDT 
+    uintptr_t vm_start;      //    start addr of vma    
+    uintptr_t vm_end;        // end addr of vma
+    uint32_t vm_flags;       // flags of vma
+    list_entry_t list_link;  // linear list link which sorted by start addr of vma
+};
+
+#define le2vma(le, member)                  \
+    to_struct((le), struct vma_struct, member)
+
+#define VM_READ                 0x00000001
+#define VM_WRITE                0x00000002
+#define VM_EXEC                 0x00000004
+#define VM_STACK                0x00000008
+
+// the control struct for a set of vma using the same PDT
+struct mm_struct {
+    list_entry_t mmap_list;        // linear list link which sorted by start addr of vma
+    struct vma_struct *mmap_cache; // current accessed vma, used for speed purpose
+    pde_t *pgdir;                  // the PDT of these vma
+    int map_count;                 // the count of these vma
+    void *sm_priv;                 // the private data for swap manager
+    int mm_count;                  // the number ofprocess which shared the mm
+    lock_t mm_lock;                // mutex for using dup_mmap fun to duplicat the mm
+};
+
+struct vma_struct *find_vma(struct mm_struct *mm, uintptr_t addr);
+struct vma_struct *vma_create(uintptr_t vm_start, uintptr_t vm_end, uint32_t vm_flags);
+void insert_vma_struct(struct mm_struct *mm, struct vma_struct *vma);
+
+struct mm_struct *mm_create(void);
+void mm_destroy(struct mm_struct *mm);
+
+void vmm_init(void);
+int mm_map(struct mm_struct *mm, uintptr_t addr, size_t len, uint32_t vm_flags,
+           struct vma_struct **vma_store);
+int do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr);
+
+int mm_unmap(struct mm_struct *mm, uintptr_t addr, size_t len);
+int dup_mmap(struct mm_struct *to, struct mm_struct *from);
+void exit_mmap(struct mm_struct *mm);
+uintptr_t get_unmapped_area(struct mm_struct *mm, size_t len);
+int mm_brk(struct mm_struct *mm, uintptr_t addr, size_t len);
+
+extern volatile unsigned int pgfault_num;
+extern struct mm_struct *check_mm_struct;
+
+bool user_mem_check(struct mm_struct *mm, uintptr_t start, size_t len, bool write);
+bool copy_from_user(struct mm_struct *mm, void *dst, const void *src, size_t len, bool writable);
+bool copy_to_user(struct mm_struct *mm, void *dst, const void *src, size_t len);
+
+static inline int
+mm_count(struct mm_struct *mm) {
+    return mm->mm_count;
+}
+
+static inline void
+set_mm_count(struct mm_struct *mm, int val) {
+    mm->mm_count = val;
+}
+
+static inline int
+mm_count_inc(struct mm_struct *mm) {
+    mm->mm_count += 1;
+    return mm->mm_count;
+}
+
+static inline int
+mm_count_dec(struct mm_struct *mm) {
+    mm->mm_count -= 1;
+    return mm->mm_count;
+}
+
+static inline void
+lock_mm(struct mm_struct *mm) {
+    if (mm != NULL) {
+        lock(&(mm->mm_lock));
+    }
+}
+
+static inline void
+unlock_mm(struct mm_struct *mm) {
+    if (mm != NULL) {
+        unlock(&(mm->mm_lock));
+    }
+}
+
+#endif /* !__KERN_MM_VMM_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/process/entry.S b/related_info/lab5/lab5-spoc-discuss/kern/process/entry.S
new file mode 100644
index 0000000..7482e23
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/process/entry.S
@@ -0,0 +1,10 @@
+.text
+.globl kernel_thread_entry
+kernel_thread_entry:        # void kernel_thread(void)
+
+    pushl %edx              # push arg
+    call *%ebx              # call fn
+
+    pushl %eax              # save the return value of fn(arg)
+    call do_exit            # call do_exit to terminate current thread
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/process/proc.c b/related_info/lab5/lab5-spoc-discuss/kern/process/proc.c
new file mode 100644
index 0000000..686708a
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/process/proc.c
@@ -0,0 +1,888 @@
+#include <proc.h>
+#include <kmalloc.h>
+#include <string.h>
+#include <sync.h>
+#include <pmm.h>
+#include <error.h>
+#include <sched.h>
+#include <elf.h>
+#include <vmm.h>
+#include <trap.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <unistd.h>
+
+/* ------------- process/thread mechanism design&implementation -------------
+(an simplified Linux process/thread mechanism )
+introduction:
+  ucore implements a simple process/thread mechanism. process contains the independent memory sapce, at least one threads
+for execution, the kernel data(for management), processor state (for context switch), files(in lab6), etc. ucore needs to
+manage all these details efficiently. In ucore, a thread is just a special kind of process(share process's memory).
+------------------------------
+process state       :     meaning               -- reason
+    PROC_UNINIT     :   uninitialized           -- alloc_proc
+    PROC_SLEEPING   :   sleeping                -- try_free_pages, do_wait, do_sleep
+    PROC_RUNNABLE   :   runnable(maybe running) -- proc_init, wakeup_proc, 
+    PROC_ZOMBIE     :   almost dead             -- do_exit
+
+-----------------------------
+process state changing:
+                                            
+  alloc_proc                                 RUNNING
+      +                                   +--<----<--+
+      +                                   + proc_run +
+      V                                   +-->---->--+ 
+PROC_UNINIT -- proc_init/wakeup_proc --> PROC_RUNNABLE -- try_free_pages/do_wait/do_sleep --> PROC_SLEEPING --
+                                           A      +                                                           +
+                                           |      +--- do_exit --> PROC_ZOMBIE                                +
+                                           +                                                                  + 
+                                           -----------------------wakeup_proc----------------------------------
+-----------------------------
+process relations
+parent:           proc->parent  (proc is children)
+children:         proc->cptr    (proc is parent)
+older sibling:    proc->optr    (proc is younger sibling)
+younger sibling:  proc->yptr    (proc is older sibling)
+-----------------------------
+related syscall for process:
+SYS_exit        : process exit,                           -->do_exit
+SYS_fork        : create child process, dup mm            -->do_fork-->wakeup_proc
+SYS_wait        : wait process                            -->do_wait
+SYS_exec        : after fork, process execute a program   -->load a program and refresh the mm
+SYS_clone       : create child thread                     -->do_fork-->wakeup_proc
+SYS_yield       : process flag itself need resecheduling, -- proc->need_sched=1, then scheduler will rescheule this process
+SYS_sleep       : process sleep                           -->do_sleep 
+SYS_kill        : kill process                            -->do_kill-->proc->flags |= PF_EXITING
+                                                                 -->wakeup_proc-->do_wait-->do_exit   
+SYS_getpid      : get the process's pid
+
+*/
+
+// the process set's list
+list_entry_t proc_list;
+
+#define HASH_SHIFT          10
+#define HASH_LIST_SIZE      (1 << HASH_SHIFT)
+#define pid_hashfn(x)       (hash32(x, HASH_SHIFT))
+
+// has list for process set based on pid
+static list_entry_t hash_list[HASH_LIST_SIZE];
+
+// idle proc
+struct proc_struct *idleproc = NULL;
+// init proc
+struct proc_struct *initproc = NULL;
+// current proc
+struct proc_struct *current = NULL;
+
+static int nr_process = 0;
+
+void kernel_thread_entry(void);
+void forkrets(struct trapframe *tf);
+void switch_to(struct context *from, struct context *to);
+
+// alloc_proc - alloc a proc_struct and init all fields of proc_struct
+static struct proc_struct *
+alloc_proc(void) {
+    struct proc_struct *proc = kmalloc(sizeof(struct proc_struct));
+    if (proc != NULL) {
+    //LAB4:EXERCISE1 YOUR CODE
+    /*
+     * below fields in proc_struct need to be initialized
+     *       enum proc_state state;                      // Process state
+     *       int pid;                                    // Process ID
+     *       int runs;                                   // the running times of Proces
+     *       uintptr_t kstack;                           // Process kernel stack
+     *       volatile bool need_resched;                 // bool value: need to be rescheduled to release CPU?
+     *       struct proc_struct *parent;                 // the parent process
+     *       struct mm_struct *mm;                       // Process's memory management field
+     *       struct context context;                     // Switch here to run process
+     *       struct trapframe *tf;                       // Trap frame for current interrupt
+     *       uintptr_t cr3;                              // CR3 register: the base addr of Page Directroy Table(PDT)
+     *       uint32_t flags;                             // Process flag
+     *       char name[PROC_NAME_LEN + 1];               // Process name
+     */
+        proc->state = PROC_UNINIT;
+        proc->pid = -1;
+        proc->runs = 0;
+        proc->kstack = 0;
+        proc->need_resched = 0;
+        proc->parent = NULL;
+        proc->mm = NULL;
+        memset(&(proc->context), 0, sizeof(struct context));
+        proc->tf = NULL;
+        proc->cr3 = boot_cr3;
+        proc->flags = 0;
+        memset(proc->name, 0, PROC_NAME_LEN);
+        proc->wait_state = 0;
+        proc->cptr = proc->optr = proc->yptr = NULL;
+    }
+    return proc;
+}
+
+// set_proc_name - set the name of proc
+char *
+set_proc_name(struct proc_struct *proc, const char *name) {
+    memset(proc->name, 0, sizeof(proc->name));
+    return memcpy(proc->name, name, PROC_NAME_LEN);
+}
+
+// get_proc_name - get the name of proc
+char *
+get_proc_name(struct proc_struct *proc) {
+    static char name[PROC_NAME_LEN + 1];
+    memset(name, 0, sizeof(name));
+    return memcpy(name, proc->name, PROC_NAME_LEN);
+}
+
+// set_links - set the relation links of process
+static void
+set_links(struct proc_struct *proc) {
+    list_add(&proc_list, &(proc->list_link));
+    proc->yptr = NULL;
+    if ((proc->optr = proc->parent->cptr) != NULL) {
+        proc->optr->yptr = proc;
+    }
+    proc->parent->cptr = proc;
+    nr_process ++;
+}
+
+// remove_links - clean the relation links of process
+static void
+remove_links(struct proc_struct *proc) {
+    list_del(&(proc->list_link));
+    if (proc->optr != NULL) {
+        proc->optr->yptr = proc->yptr;
+    }
+    if (proc->yptr != NULL) {
+        proc->yptr->optr = proc->optr;
+    }
+    else {
+       proc->parent->cptr = proc->optr;
+    }
+    nr_process --;
+}
+
+// get_pid - alloc a unique pid for process
+static int
+get_pid(void) {
+    static_assert(MAX_PID > MAX_PROCESS);
+    struct proc_struct *proc;
+    list_entry_t *list = &proc_list, *le;
+    static int next_safe = MAX_PID, last_pid = MAX_PID;
+    if (++ last_pid >= MAX_PID) {
+        last_pid = 1;
+        goto inside;
+    }
+    if (last_pid >= next_safe) {
+    inside:
+        next_safe = MAX_PID;
+    repeat:
+        le = list;
+        while ((le = list_next(le)) != list) {
+            proc = le2proc(le, list_link);
+            if (proc->pid == last_pid) {
+                if (++ last_pid >= next_safe) {
+                    if (last_pid >= MAX_PID) {
+                        last_pid = 1;
+                    }
+                    next_safe = MAX_PID;
+                    goto repeat;
+                }
+            }
+            else if (proc->pid > last_pid && next_safe > proc->pid) {
+                next_safe = proc->pid;
+            }
+        }
+    }
+    return last_pid;
+}
+
+// proc_run - make process "proc" running on cpu
+// NOTE: before call switch_to, should load  base addr of "proc"'s new PDT
+void
+proc_run(struct proc_struct *proc) {
+    if (proc != current) {
+        bool intr_flag;
+        struct proc_struct *prev = current, *next = proc;
+        local_intr_save(intr_flag);
+        {
+            current = proc;
+            load_esp0(next->kstack + KSTACKSIZE);
+            lcr3(next->cr3);
+            switch_to(&(prev->context), &(next->context));
+        }
+        local_intr_restore(intr_flag);
+    }
+}
+
+// forkret -- the first kernel entry point of a new thread/process
+// NOTE: the addr of forkret is setted in copy_thread function
+//       after switch_to, the current proc will execute here.
+static void
+forkret(void) {
+    forkrets(current->tf);
+}
+
+// hash_proc - add proc into proc hash_list
+static void
+hash_proc(struct proc_struct *proc) {
+    list_add(hash_list + pid_hashfn(proc->pid), &(proc->hash_link));
+}
+
+// unhash_proc - delete proc from proc hash_list
+static void
+unhash_proc(struct proc_struct *proc) {
+    list_del(&(proc->hash_link));
+}
+
+// find_proc - find proc frome proc hash_list according to pid
+struct proc_struct *
+find_proc(int pid) {
+    if (0 < pid && pid < MAX_PID) {
+        list_entry_t *list = hash_list + pid_hashfn(pid), *le = list;
+        while ((le = list_next(le)) != list) {
+            struct proc_struct *proc = le2proc(le, hash_link);
+            if (proc->pid == pid) {
+                return proc;
+            }
+        }
+    }
+    return NULL;
+}
+
+// kernel_thread - create a kernel thread using "fn" function
+// NOTE: the contents of temp trapframe tf will be copied to 
+//       proc->tf in do_fork-->copy_thread function
+int
+kernel_thread(int (*fn)(void *), void *arg, uint32_t clone_flags) {
+    struct trapframe tf;
+    memset(&tf, 0, sizeof(struct trapframe));
+    tf.tf_cs = KERNEL_CS;
+    tf.tf_ds = tf.tf_es = tf.tf_ss = KERNEL_DS;
+    tf.tf_regs.reg_ebx = (uint32_t)fn;
+    tf.tf_regs.reg_edx = (uint32_t)arg;
+    tf.tf_eip = (uint32_t)kernel_thread_entry;
+    return do_fork(clone_flags | CLONE_VM, 0, &tf);
+}
+
+// setup_kstack - alloc pages with size KSTACKPAGE as process kernel stack
+static int
+setup_kstack(struct proc_struct *proc) {
+    struct Page *page = alloc_pages(KSTACKPAGE);
+    if (page != NULL) {
+        proc->kstack = (uintptr_t)page2kva(page);
+        return 0;
+    }
+    return -E_NO_MEM;
+}
+
+// put_kstack - free the memory space of process kernel stack
+static void
+put_kstack(struct proc_struct *proc) {
+    free_pages(kva2page((void *)(proc->kstack)), KSTACKPAGE);
+}
+
+// setup_pgdir - alloc one page as PDT
+static int
+setup_pgdir(struct mm_struct *mm) {
+    struct Page *page;
+    if ((page = alloc_page()) == NULL) {
+        return -E_NO_MEM;
+    }
+    pde_t *pgdir = page2kva(page);
+    memcpy(pgdir, boot_pgdir, PGSIZE);
+    pgdir[PDX(VPT)] = PADDR(pgdir) | PTE_P | PTE_W;
+    mm->pgdir = pgdir;
+    return 0;
+}
+
+// put_pgdir - free the memory space of PDT
+static void
+put_pgdir(struct mm_struct *mm) {
+    free_page(kva2page(mm->pgdir));
+}
+
+// copy_mm - process "proc" duplicate OR share process "current"'s mm according clone_flags
+//         - if clone_flags & CLONE_VM, then "share" ; else "duplicate"
+static int
+copy_mm(uint32_t clone_flags, struct proc_struct *proc) {
+    struct mm_struct *mm, *oldmm = current->mm;
+
+    /* current is a kernel thread */
+    if (oldmm == NULL) {
+        return 0;
+    }
+    if (clone_flags & CLONE_VM) {
+        mm = oldmm;
+        goto good_mm;
+    }
+
+    int ret = -E_NO_MEM;
+    if ((mm = mm_create()) == NULL) {
+        goto bad_mm;
+    }
+    if (setup_pgdir(mm) != 0) {
+        goto bad_pgdir_cleanup_mm;
+    }
+
+    lock_mm(oldmm);
+    {
+        ret = dup_mmap(mm, oldmm);
+    }
+    unlock_mm(oldmm);
+
+    if (ret != 0) {
+        goto bad_dup_cleanup_mmap;
+    }
+
+good_mm:
+    mm_count_inc(mm);
+    proc->mm = mm;
+    proc->cr3 = PADDR(mm->pgdir);
+    return 0;
+bad_dup_cleanup_mmap:
+    exit_mmap(mm);
+    put_pgdir(mm);
+bad_pgdir_cleanup_mm:
+    mm_destroy(mm);
+bad_mm:
+    return ret;
+}
+
+// copy_thread - setup the trapframe on the  process's kernel stack top and
+//             - setup the kernel entry point and stack of process
+static void
+copy_thread(struct proc_struct *proc, uintptr_t esp, struct trapframe *tf) {
+    proc->tf = (struct trapframe *)(proc->kstack + KSTACKSIZE) - 1;
+    *(proc->tf) = *tf;
+    proc->tf->tf_regs.reg_eax = 0;
+    proc->tf->tf_esp = esp;
+    proc->tf->tf_eflags |= FL_IF;
+
+    proc->context.eip = (uintptr_t)forkret;
+    proc->context.esp = (uintptr_t)(proc->tf);
+}
+
+/* do_fork -     parent process for a new child process
+ * @clone_flags: used to guide how to clone the child process
+ * @stack:       the parent's user stack pointer. if stack==0, It means to fork a kernel thread.
+ * @tf:          the trapframe info, which will be copied to child process's proc->tf
+ */
+int
+do_fork(uint32_t clone_flags, uintptr_t stack, struct trapframe *tf) {
+    int ret = -E_NO_FREE_PROC;
+    struct proc_struct *proc;
+    if (nr_process >= MAX_PROCESS) {
+        goto fork_out;
+    }
+    ret = -E_NO_MEM;
+    //LAB4:EXERCISE2 YOUR CODE
+    /*
+     * Some Useful MACROs, Functions and DEFINEs, you can use them in below implementation.
+     * MACROs or Functions:
+     *   alloc_proc:   create a proc struct and init fields (lab4:exercise1)
+     *   setup_kstack: alloc pages with size KSTACKPAGE as process kernel stack
+     *   copy_mm:      process "proc" duplicate OR share process "current"'s mm according clone_flags
+     *                 if clone_flags & CLONE_VM, then "share" ; else "duplicate"
+     *   copy_thread:  setup the trapframe on the  process's kernel stack top and
+     *                 setup the kernel entry point and stack of process
+     *   hash_proc:    add proc into proc hash_list
+     *   get_pid:      alloc a unique pid for process
+     *   wakup_proc:   set proc->state = PROC_RUNNABLE
+     * VARIABLES:
+     *   proc_list:    the process set's list
+     *   nr_process:   the number of process set
+     */
+
+    //    1. call alloc_proc to allocate a proc_struct
+    //    2. call setup_kstack to allocate a kernel stack for child process
+    //    3. call copy_mm to dup OR share mm according clone_flag
+    //    4. call copy_thread to setup tf & context in proc_struct
+    //    5. insert proc_struct into hash_list && proc_list
+    //    6. call wakup_proc to make the new child process RUNNABLE
+    //    7. set ret vaule using child proc's pid
+    if ((proc = alloc_proc()) == NULL) {
+        goto fork_out;
+    }
+
+    proc->parent = current;
+    assert(current->wait_state == 0);
+
+    if (setup_kstack(proc) != 0) {
+        goto bad_fork_cleanup_proc;
+    }
+    if (copy_mm(clone_flags, proc) != 0) {
+        goto bad_fork_cleanup_kstack;
+    }
+    copy_thread(proc, stack, tf);
+
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        proc->pid = get_pid();
+        hash_proc(proc);
+        set_links(proc);
+
+    }
+    local_intr_restore(intr_flag);
+
+    wakeup_proc(proc);
+
+    ret = proc->pid;
+fork_out:
+    return ret;
+
+bad_fork_cleanup_kstack:
+    put_kstack(proc);
+bad_fork_cleanup_proc:
+    kfree(proc);
+    goto fork_out;
+}
+
+// do_exit - called by sys_exit
+//   1. call exit_mmap & put_pgdir & mm_destroy to free the almost all memory space of process
+//   2. set process' state as PROC_ZOMBIE, then call wakeup_proc(parent) to ask parent reclaim itself.
+//   3. call scheduler to switch to other process
+int
+do_exit(int error_code) {
+    if (current == idleproc) {
+        panic("idleproc exit.\n");
+    }
+    if (current == initproc) {
+        panic("initproc exit.\n");
+    }
+    
+    struct mm_struct *mm = current->mm;
+    if (mm != NULL) {
+        lcr3(boot_cr3);
+        if (mm_count_dec(mm) == 0) {
+            exit_mmap(mm);
+            put_pgdir(mm);
+            mm_destroy(mm);
+        }
+        current->mm = NULL;
+    }
+    current->state = PROC_ZOMBIE;
+    current->exit_code = error_code;
+    
+    bool intr_flag;
+    struct proc_struct *proc;
+    local_intr_save(intr_flag);
+    {
+        proc = current->parent;
+        if (proc->wait_state == WT_CHILD) {
+            wakeup_proc(proc);
+        }
+        while (current->cptr != NULL) {
+            proc = current->cptr;
+            current->cptr = proc->optr;
+    
+            proc->yptr = NULL;
+            if ((proc->optr = initproc->cptr) != NULL) {
+                initproc->cptr->yptr = proc;
+            }
+            proc->parent = initproc;
+            initproc->cptr = proc;
+            if (proc->state == PROC_ZOMBIE) {
+                if (initproc->wait_state == WT_CHILD) {
+                    wakeup_proc(initproc);
+                }
+            }
+        }
+    }
+    local_intr_restore(intr_flag);
+    
+    schedule();
+    panic("do_exit will not return!! %d.\n", current->pid);
+}
+
+/* load_icode - load the content of binary program(ELF format) as the new content of current process
+ * @binary:  the memory addr of the content of binary program
+ * @size:  the size of the content of binary program
+ */
+static int
+load_icode(unsigned char *binary, size_t size) {
+    if (current->mm != NULL) {
+        panic("load_icode: current->mm must be empty.\n");
+    }
+
+    int ret = -E_NO_MEM;
+    struct mm_struct *mm;
+    //(1) create a new mm for current process
+    if ((mm = mm_create()) == NULL) {
+        goto bad_mm;
+    }
+    //(2) create a new PDT, and mm->pgdir= kernel virtual addr of PDT
+    if (setup_pgdir(mm) != 0) {
+        goto bad_pgdir_cleanup_mm;
+    }
+    //(3) copy TEXT/DATA section, build BSS parts in binary to memory space of process
+    struct Page *page;
+    //(3.1) get the file header of the bianry program (ELF format)
+    struct elfhdr *elf = (struct elfhdr *)binary;
+    //(3.2) get the entry of the program section headers of the bianry program (ELF format)
+    struct proghdr *ph = (struct proghdr *)(binary + elf->e_phoff);
+    //(3.3) This program is valid?
+    if (elf->e_magic != ELF_MAGIC) {
+        ret = -E_INVAL_ELF;
+        goto bad_elf_cleanup_pgdir;
+    }
+
+    uint32_t vm_flags, perm;
+    struct proghdr *ph_end = ph + elf->e_phnum;
+    for (; ph < ph_end; ph ++) {
+    //(3.4) find every program section headers
+        if (ph->p_type != ELF_PT_LOAD) {
+            continue ;
+        }
+        if (ph->p_filesz > ph->p_memsz) {
+            ret = -E_INVAL_ELF;
+            goto bad_cleanup_mmap;
+        }
+        if (ph->p_filesz == 0) {
+            continue ;
+        }
+    //(3.5) call mm_map fun to setup the new vma ( ph->p_va, ph->p_memsz)
+        vm_flags = 0, perm = PTE_U;
+        if (ph->p_flags & ELF_PF_X) vm_flags |= VM_EXEC;
+        if (ph->p_flags & ELF_PF_W) vm_flags |= VM_WRITE;
+        if (ph->p_flags & ELF_PF_R) vm_flags |= VM_READ;
+        if (vm_flags & VM_WRITE) perm |= PTE_W;
+        if ((ret = mm_map(mm, ph->p_va, ph->p_memsz, vm_flags, NULL)) != 0) {
+            goto bad_cleanup_mmap;
+        }
+        unsigned char *from = binary + ph->p_offset;
+        size_t off, size;
+        uintptr_t start = ph->p_va, end, la = ROUNDDOWN(start, PGSIZE);
+
+        ret = -E_NO_MEM;
+
+     //(3.6) alloc memory, and  copy the contents of every program section (from, from+end) to process's memory (la, la+end)
+        end = ph->p_va + ph->p_filesz;
+     //(3.6.1) copy TEXT/DATA section of bianry program
+        while (start < end) {
+            if ((page = pgdir_alloc_page(mm->pgdir, la, perm)) == NULL) {
+                goto bad_cleanup_mmap;
+            }
+            off = start - la, size = PGSIZE - off, la += PGSIZE;
+            if (end < la) {
+                size -= la - end;
+            }
+            memcpy(page2kva(page) + off, from, size);
+            start += size, from += size;
+        }
+
+      //(3.6.2) build BSS section of binary program
+        end = ph->p_va + ph->p_memsz;
+        if (start < la) {
+            /* ph->p_memsz == ph->p_filesz */
+            if (start == end) {
+                continue ;
+            }
+            off = start + PGSIZE - la, size = PGSIZE - off;
+            if (end < la) {
+                size -= la - end;
+            }
+            memset(page2kva(page) + off, 0, size);
+            start += size;
+            assert((end < la && start == end) || (end >= la && start == la));
+        }
+        while (start < end) {
+            if ((page = pgdir_alloc_page(mm->pgdir, la, perm)) == NULL) {
+                goto bad_cleanup_mmap;
+            }
+            off = start - la, size = PGSIZE - off, la += PGSIZE;
+            if (end < la) {
+                size -= la - end;
+            }
+            memset(page2kva(page) + off, 0, size);
+            start += size;
+        }
+    }
+    //(4) build user stack memory
+    vm_flags = VM_READ | VM_WRITE | VM_STACK;
+    if ((ret = mm_map(mm, USTACKTOP - USTACKSIZE, USTACKSIZE, vm_flags, NULL)) != 0) {
+        goto bad_cleanup_mmap;
+    }
+    assert(pgdir_alloc_page(mm->pgdir, USTACKTOP-PGSIZE , PTE_USER) != NULL);
+    assert(pgdir_alloc_page(mm->pgdir, USTACKTOP-2*PGSIZE , PTE_USER) != NULL);
+    assert(pgdir_alloc_page(mm->pgdir, USTACKTOP-3*PGSIZE , PTE_USER) != NULL);
+    assert(pgdir_alloc_page(mm->pgdir, USTACKTOP-4*PGSIZE , PTE_USER) != NULL);
+    
+    //(5) set current process's mm, sr3, and set CR3 reg = physical addr of Page Directory
+    mm_count_inc(mm);
+    current->mm = mm;
+    current->cr3 = PADDR(mm->pgdir);
+    lcr3(PADDR(mm->pgdir));
+
+    //(6) setup trapframe for user environment
+    struct trapframe *tf = current->tf;
+    memset(tf, 0, sizeof(struct trapframe));
+    /* LAB5:EXERCISE1 YOUR CODE
+     * should set tf_cs,tf_ds,tf_es,tf_ss,tf_esp,tf_eip,tf_eflags
+     * NOTICE: If we set trapframe correctly, then the user level process can return to USER MODE from kernel. So
+     *          tf_cs should be USER_CS segment (see memlayout.h)
+     *          tf_ds=tf_es=tf_ss should be USER_DS segment
+     *          tf_esp should be the top addr of user stack (USTACKTOP)
+     *          tf_eip should be the entry point of this binary program (elf->e_entry)
+     *          tf_eflags should be set to enable computer to produce Interrupt
+     */
+    tf->tf_cs = USER_CS;
+    tf->tf_ds = tf->tf_es = tf->tf_ss = USER_DS;
+    tf->tf_esp = USTACKTOP;
+    tf->tf_eip = elf->e_entry;
+    tf->tf_eflags = FL_IF;
+    ret = 0;
+out:
+    return ret;
+bad_cleanup_mmap:
+    exit_mmap(mm);
+bad_elf_cleanup_pgdir:
+    put_pgdir(mm);
+bad_pgdir_cleanup_mm:
+    mm_destroy(mm);
+bad_mm:
+    goto out;
+}
+
+// do_execve - call exit_mmap(mm)&pug_pgdir(mm) to reclaim memory space of current process
+//           - call load_icode to setup new memory space accroding binary prog.
+int
+do_execve(const char *name, size_t len, unsigned char *binary, size_t size) {
+    struct mm_struct *mm = current->mm;
+    if (!user_mem_check(mm, (uintptr_t)name, len, 0)) {
+        return -E_INVAL;
+    }
+    if (len > PROC_NAME_LEN) {
+        len = PROC_NAME_LEN;
+    }
+
+    char local_name[PROC_NAME_LEN + 1];
+    memset(local_name, 0, sizeof(local_name));
+    memcpy(local_name, name, len);
+
+    if (mm != NULL) {
+        lcr3(boot_cr3);
+        if (mm_count_dec(mm) == 0) {
+            exit_mmap(mm);
+            put_pgdir(mm);
+            mm_destroy(mm);
+        }
+        current->mm = NULL;
+    }
+    int ret;
+    if ((ret = load_icode(binary, size)) != 0) {
+        goto execve_exit;
+    }
+    set_proc_name(current, local_name);
+    return 0;
+
+execve_exit:
+    do_exit(ret);
+    panic("already exit: %e.\n", ret);
+}
+
+// do_yield - ask the scheduler to reschedule
+int
+do_yield(void) {
+    current->need_resched = 1;
+    return 0;
+}
+
+// do_wait - wait one OR any children with PROC_ZOMBIE state, and free memory space of kernel stack
+//         - proc struct of this child.
+// NOTE: only after do_wait function, all resources of the child proces are free.
+int
+do_wait(int pid, int *code_store) {
+    struct mm_struct *mm = current->mm;
+    if (code_store != NULL) {
+        if (!user_mem_check(mm, (uintptr_t)code_store, sizeof(int), 1)) {
+            return -E_INVAL;
+        }
+    }
+
+    struct proc_struct *proc;
+    bool intr_flag, haskid;
+repeat:
+    haskid = 0;
+    if (pid != 0) {
+        proc = find_proc(pid);
+        if (proc != NULL && proc->parent == current) {
+            haskid = 1;
+            if (proc->state == PROC_ZOMBIE) {
+                goto found;
+            }
+        }
+    }
+    else {
+        proc = current->cptr;
+        for (; proc != NULL; proc = proc->optr) {
+            haskid = 1;
+            if (proc->state == PROC_ZOMBIE) {
+                goto found;
+            }
+        }
+    }
+    if (haskid) {
+        current->state = PROC_SLEEPING;
+        current->wait_state = WT_CHILD;
+        schedule();
+        if (current->flags & PF_EXITING) {
+            do_exit(-E_KILLED);
+        }
+        goto repeat;
+    }
+    return -E_BAD_PROC;
+
+found:
+    if (proc == idleproc || proc == initproc) {
+        panic("wait idleproc or initproc.\n");
+    }
+    if (code_store != NULL) {
+        *code_store = proc->exit_code;
+    }
+    local_intr_save(intr_flag);
+    {
+        unhash_proc(proc);
+        remove_links(proc);
+    }
+    local_intr_restore(intr_flag);
+    put_kstack(proc);
+    kfree(proc);
+    return 0;
+}
+
+// do_kill - kill process with pid by set this process's flags with PF_EXITING
+int
+do_kill(int pid) {
+    struct proc_struct *proc;
+    if ((proc = find_proc(pid)) != NULL) {
+        if (!(proc->flags & PF_EXITING)) {
+            proc->flags |= PF_EXITING;
+            if (proc->wait_state & WT_INTERRUPTED) {
+                wakeup_proc(proc);
+            }
+            return 0;
+        }
+        return -E_KILLED;
+    }
+    return -E_INVAL;
+}
+
+// kernel_execve - do SYS_exec syscall to exec a user program called by user_main kernel_thread
+static int
+kernel_execve(const char *name, unsigned char *binary, size_t size) {
+    int ret, len = strlen(name);
+    asm volatile (
+        "int %1;"
+        : "=a" (ret)
+        : "i" (T_SYSCALL), "0" (SYS_exec), "d" (name), "c" (len), "b" (binary), "D" (size)
+        : "memory");
+    return ret;
+}
+
+#define __KERNEL_EXECVE(name, binary, size) ({                          \
+            cprintf("kernel_execve: pid = %d, name = \"%s\".\n",        \
+                    current->pid, name);                                \
+            kernel_execve(name, binary, (size_t)(size));                \
+        })
+
+#define KERNEL_EXECVE(x) ({                                             \
+            extern unsigned char _binary_obj___user_##x##_out_start[],  \
+                _binary_obj___user_##x##_out_size[];                    \
+            __KERNEL_EXECVE(#x, _binary_obj___user_##x##_out_start,     \
+                            _binary_obj___user_##x##_out_size);         \
+        })
+
+#define __KERNEL_EXECVE2(x, xstart, xsize) ({                           \
+            extern unsigned char xstart[], xsize[];                     \
+            __KERNEL_EXECVE(#x, xstart, (size_t)xsize);                 \
+        })
+
+#define KERNEL_EXECVE2(x, xstart, xsize)        __KERNEL_EXECVE2(x, xstart, xsize)
+
+// user_main - kernel thread used to exec a user program
+static int
+user_main(void *arg) {
+#ifdef TEST
+    KERNEL_EXECVE2(TEST, TESTSTART, TESTSIZE);
+#else
+    KERNEL_EXECVE(exit);
+#endif
+    panic("user_main execve failed.\n");
+}
+
+// init_main - the second kernel thread used to create user_main kernel threads
+static int
+init_main(void *arg) {
+    size_t nr_free_pages_store = nr_free_pages();
+    size_t kernel_allocated_store = kallocated();
+
+    int pid = kernel_thread(user_main, NULL, 0);
+    if (pid <= 0) {
+        panic("create user_main failed.\n");
+    }
+
+    while (do_wait(0, NULL) == 0) {
+        schedule();
+    }
+
+    cprintf("all user-mode processes have quit.\n");
+    assert(initproc->cptr == NULL && initproc->yptr == NULL && initproc->optr == NULL);
+    assert(nr_process == 2);
+    assert(list_next(&proc_list) == &(initproc->list_link));
+    assert(list_prev(&proc_list) == &(initproc->list_link));
+    assert(nr_free_pages_store == nr_free_pages());
+    assert(kernel_allocated_store == kallocated());
+    cprintf("init check memory pass.\n");
+    return 0;
+}
+
+// proc_init - set up the first kernel thread idleproc "idle" by itself and 
+//           - create the second kernel thread init_main
+void
+proc_init(void) {
+    int i;
+
+    list_init(&proc_list);
+    for (i = 0; i < HASH_LIST_SIZE; i ++) {
+        list_init(hash_list + i);
+    }
+
+    if ((idleproc = alloc_proc()) == NULL) {
+        panic("cannot alloc idleproc.\n");
+    }
+
+    idleproc->pid = 0;
+    idleproc->state = PROC_RUNNABLE;
+    idleproc->kstack = (uintptr_t)bootstack;
+    idleproc->need_resched = 1;
+    set_proc_name(idleproc, "idle");
+    nr_process ++;
+
+    current = idleproc;
+
+    int pid = kernel_thread(init_main, NULL, 0);
+    if (pid <= 0) {
+        panic("create init_main failed.\n");
+    }
+
+    initproc = find_proc(pid);
+    set_proc_name(initproc, "init");
+
+    assert(idleproc != NULL && idleproc->pid == 0);
+    assert(initproc != NULL && initproc->pid == 1);
+}
+
+// cpu_idle - at the end of kern_init, the first kernel thread idleproc will do below works
+void
+cpu_idle(void) {
+    while (1) {
+        if (current->need_resched) {
+            schedule();
+        }
+    }
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/process/proc.h b/related_info/lab5/lab5-spoc-discuss/kern/process/proc.h
new file mode 100644
index 0000000..a1f12d8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/process/proc.h
@@ -0,0 +1,89 @@
+#ifndef __KERN_PROCESS_PROC_H__
+#define __KERN_PROCESS_PROC_H__
+
+#include <defs.h>
+#include <list.h>
+#include <trap.h>
+#include <memlayout.h>
+
+
+// process's state in his life cycle
+enum proc_state {
+    PROC_UNINIT = 0,  // uninitialized
+    PROC_SLEEPING,    // sleeping
+    PROC_RUNNABLE,    // runnable(maybe running)
+    PROC_ZOMBIE,      // almost dead, and wait parent proc to reclaim his resource
+};
+
+// Saved registers for kernel context switches.
+// Don't need to save all the %fs etc. segment registers,
+// because they are constant across kernel contexts.
+// Save all the regular registers so we don't need to care
+// which are caller save, but not the return register %eax.
+// (Not saving %eax just simplifies the switching code.)
+// The layout of context must match code in switch.S.
+struct context {
+    uint32_t eip;
+    uint32_t esp;
+    uint32_t ebx;
+    uint32_t ecx;
+    uint32_t edx;
+    uint32_t esi;
+    uint32_t edi;
+    uint32_t ebp;
+};
+
+#define PROC_NAME_LEN               15
+#define MAX_PROCESS                 4096
+#define MAX_PID                     (MAX_PROCESS * 2)
+
+extern list_entry_t proc_list;
+
+struct proc_struct {
+    enum proc_state state;                      // Process state
+    int pid;                                    // Process ID
+    int runs;                                   // the running times of Proces
+    uintptr_t kstack;                           // Process kernel stack
+    volatile bool need_resched;                 // bool value: need to be rescheduled to release CPU?
+    struct proc_struct *parent;                 // the parent process
+    struct mm_struct *mm;                       // Process's memory management field
+    struct context context;                     // Switch here to run process
+    struct trapframe *tf;                       // Trap frame for current interrupt
+    uintptr_t cr3;                              // CR3 register: the base addr of Page Directroy Table(PDT)
+    uint32_t flags;                             // Process flag
+    char name[PROC_NAME_LEN + 1];               // Process name
+    list_entry_t list_link;                     // Process link list 
+    list_entry_t hash_link;                     // Process hash list
+    int exit_code;                              // exit code (be sent to parent proc)
+    uint32_t wait_state;                        // waiting state
+    struct proc_struct *cptr, *yptr, *optr;     // relations between processes
+};
+
+#define PF_EXITING                  0x00000001      // getting shutdown
+
+#define WT_CHILD                    (0x00000001 | WT_INTERRUPTED)
+#define WT_INTERRUPTED               0x80000000                    // the wait state could be interrupted
+
+
+#define le2proc(le, member)         \
+    to_struct((le), struct proc_struct, member)
+
+extern struct proc_struct *idleproc, *initproc, *current;
+
+void proc_init(void);
+void proc_run(struct proc_struct *proc);
+int kernel_thread(int (*fn)(void *), void *arg, uint32_t clone_flags);
+
+char *set_proc_name(struct proc_struct *proc, const char *name);
+char *get_proc_name(struct proc_struct *proc);
+void cpu_idle(void) __attribute__((noreturn));
+
+struct proc_struct *find_proc(int pid);
+int do_fork(uint32_t clone_flags, uintptr_t stack, struct trapframe *tf);
+int do_exit(int error_code);
+int do_yield(void);
+int do_execve(const char *name, size_t len, unsigned char *binary, size_t size);
+int do_wait(int pid, int *code_store);
+int do_kill(int pid);
+#endif /* !__KERN_PROCESS_PROC_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/process/switch.S b/related_info/lab5/lab5-spoc-discuss/kern/process/switch.S
new file mode 100644
index 0000000..27b4c8c
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/process/switch.S
@@ -0,0 +1,30 @@
+.text
+.globl switch_to
+switch_to:                      # switch_to(from, to)
+
+    # save from's registers
+    movl 4(%esp), %eax          # eax points to from
+    popl 0(%eax)                # save eip !popl
+    movl %esp, 4(%eax)
+    movl %ebx, 8(%eax)
+    movl %ecx, 12(%eax)
+    movl %edx, 16(%eax)
+    movl %esi, 20(%eax)
+    movl %edi, 24(%eax)
+    movl %ebp, 28(%eax)
+
+    # restore to's registers
+    movl 4(%esp), %eax          # not 8(%esp): popped return address already
+                                # eax now points to to
+    movl 28(%eax), %ebp
+    movl 24(%eax), %edi
+    movl 20(%eax), %esi
+    movl 16(%eax), %edx
+    movl 12(%eax), %ecx
+    movl 8(%eax), %ebx
+    movl 4(%eax), %esp
+
+    pushl 0(%eax)               # push eip
+
+    ret
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.c b/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.c
new file mode 100644
index 0000000..939caf4
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.c
@@ -0,0 +1,52 @@
+#include <list.h>
+#include <sync.h>
+#include <proc.h>
+#include <sched.h>
+#include <assert.h>
+
+void
+wakeup_proc(struct proc_struct *proc) {
+    assert(proc->state != PROC_ZOMBIE);
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        if (proc->state != PROC_RUNNABLE) {
+            proc->state = PROC_RUNNABLE;
+            proc->wait_state = 0;
+        }
+        else {
+            warn("wakeup runnable process.\n");
+        }
+    }
+    local_intr_restore(intr_flag);
+}
+
+void
+schedule(void) {
+    bool intr_flag;
+    list_entry_t *le, *last;
+    struct proc_struct *next = NULL;
+    local_intr_save(intr_flag);
+    {
+        current->need_resched = 0;
+        last = (current == idleproc) ? &proc_list : &(current->list_link);
+        le = last;
+        do {
+            if ((le = list_next(le)) != &proc_list) {
+                next = le2proc(le, list_link);
+                if (next->state == PROC_RUNNABLE) {
+                    break;
+                }
+            }
+        } while (le != last);
+        if (next == NULL || next->state != PROC_RUNNABLE) {
+            next = idleproc;
+        }
+        next->runs ++;
+        if (next != current) {
+            proc_run(next);
+        }
+    }
+    local_intr_restore(intr_flag);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.h b/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.h
new file mode 100644
index 0000000..ed1fc6e
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/schedule/sched.h
@@ -0,0 +1,10 @@
+#ifndef __KERN_SCHEDULE_SCHED_H__
+#define __KERN_SCHEDULE_SCHED_H__
+
+#include <proc.h>
+
+void schedule(void);
+void wakeup_proc(struct proc_struct *proc);
+
+#endif /* !__KERN_SCHEDULE_SCHED_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/sync/sync.h b/related_info/lab5/lab5-spoc-discuss/kern/sync/sync.h
new file mode 100644
index 0000000..3e75192
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/sync/sync.h
@@ -0,0 +1,57 @@
+#ifndef __KERN_SYNC_SYNC_H__
+#define __KERN_SYNC_SYNC_H__
+
+#include <x86.h>
+#include <intr.h>
+#include <mmu.h>
+#include <assert.h>
+#include <atomic.h>
+#include <sched.h>
+
+static inline bool
+__intr_save(void) {
+    if (read_eflags() & FL_IF) {
+        intr_disable();
+        return 1;
+    }
+    return 0;
+}
+
+static inline void
+__intr_restore(bool flag) {
+    if (flag) {
+        intr_enable();
+    }
+}
+
+#define local_intr_save(x)      do { x = __intr_save(); } while (0)
+#define local_intr_restore(x)   __intr_restore(x);
+
+typedef volatile bool lock_t;
+
+static inline void
+lock_init(lock_t *lock) {
+    *lock = 0;
+}
+
+static inline bool
+try_lock(lock_t *lock) {
+    return !test_and_set_bit(0, lock);
+}
+
+static inline void
+lock(lock_t *lock) {
+    while (!try_lock(lock)) {
+        schedule();
+    }
+}
+
+static inline void
+unlock(lock_t *lock) {
+    if (!test_and_clear_bit(0, lock)) {
+        panic("Unlock failed.\n");
+    }
+}
+
+#endif /* !__KERN_SYNC_SYNC_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.c b/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.c
new file mode 100644
index 0000000..7a7e4e2
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.c
@@ -0,0 +1,101 @@
+#include <unistd.h>
+#include <proc.h>
+#include <syscall.h>
+#include <trap.h>
+#include <stdio.h>
+#include <pmm.h>
+#include <assert.h>
+
+static int
+sys_exit(uint32_t arg[]) {
+    int error_code = (int)arg[0];
+    return do_exit(error_code);
+}
+
+static int
+sys_fork(uint32_t arg[]) {
+    struct trapframe *tf = current->tf;
+    uintptr_t stack = tf->tf_esp;
+    return do_fork(0, stack, tf);
+}
+
+static int
+sys_wait(uint32_t arg[]) {
+    int pid = (int)arg[0];
+    int *store = (int *)arg[1];
+    return do_wait(pid, store);
+}
+
+static int
+sys_exec(uint32_t arg[]) {
+    const char *name = (const char *)arg[0];
+    size_t len = (size_t)arg[1];
+    unsigned char *binary = (unsigned char *)arg[2];
+    size_t size = (size_t)arg[3];
+    return do_execve(name, len, binary, size);
+}
+
+static int
+sys_yield(uint32_t arg[]) {
+    return do_yield();
+}
+
+static int
+sys_kill(uint32_t arg[]) {
+    int pid = (int)arg[0];
+    return do_kill(pid);
+}
+
+static int
+sys_getpid(uint32_t arg[]) {
+    return current->pid;
+}
+
+static int
+sys_putc(uint32_t arg[]) {
+    int c = (int)arg[0];
+    cputchar(c);
+    return 0;
+}
+
+static int
+sys_pgdir(uint32_t arg[]) {
+    print_pgdir();
+    return 0;
+}
+
+static int (*syscalls[])(uint32_t arg[]) = {
+    [SYS_exit]              sys_exit,
+    [SYS_fork]              sys_fork,
+    [SYS_wait]              sys_wait,
+    [SYS_exec]              sys_exec,
+    [SYS_yield]             sys_yield,
+    [SYS_kill]              sys_kill,
+    [SYS_getpid]            sys_getpid,
+    [SYS_putc]              sys_putc,
+    [SYS_pgdir]             sys_pgdir,
+};
+
+#define NUM_SYSCALLS        ((sizeof(syscalls)) / (sizeof(syscalls[0])))
+
+void
+syscall(void) {
+    struct trapframe *tf = current->tf;
+    uint32_t arg[5];
+    int num = tf->tf_regs.reg_eax;
+    if (num >= 0 && num < NUM_SYSCALLS) {
+        if (syscalls[num] != NULL) {
+            arg[0] = tf->tf_regs.reg_edx;
+            arg[1] = tf->tf_regs.reg_ecx;
+            arg[2] = tf->tf_regs.reg_ebx;
+            arg[3] = tf->tf_regs.reg_edi;
+            arg[4] = tf->tf_regs.reg_esi;
+            tf->tf_regs.reg_eax = syscalls[num](arg);
+            return ;
+        }
+    }
+    print_trapframe(tf);
+    panic("undefined syscall %d, pid = %d, name = %s.\n",
+            num, current->pid, current->name);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.h b/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.h
new file mode 100644
index 0000000..a8fe843
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/syscall/syscall.h
@@ -0,0 +1,7 @@
+#ifndef __KERN_SYSCALL_SYSCALL_H__
+#define __KERN_SYSCALL_SYSCALL_H__
+
+void syscall(void);
+
+#endif /* !__KERN_SYSCALL_SYSCALL_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.c b/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.c
new file mode 100644
index 0000000..3514b89
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.c
@@ -0,0 +1,300 @@
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <clock.h>
+#include <trap.h>
+#include <x86.h>
+#include <stdio.h>
+#include <assert.h>
+#include <console.h>
+#include <vmm.h>
+#include <swap.h>
+#include <kdebug.h>
+#include <unistd.h>
+#include <syscall.h>
+#include <error.h>
+#include <sched.h>
+#include <sync.h>
+
+#define TICK_NUM 100
+
+static void print_ticks() {
+    cprintf("%d ticks\n",TICK_NUM);
+#ifdef DEBUG_GRADE
+    cprintf("End of Test.\n");
+    panic("EOT: kernel seems ok.");
+#endif
+}
+
+/* *
+ * Interrupt descriptor table:
+ *
+ * Must be built at run time because shifted function addresses can't
+ * be represented in relocation records.
+ * */
+static struct gatedesc idt[256] = {{0}};
+
+static struct pseudodesc idt_pd = {
+    sizeof(idt) - 1, (uintptr_t)idt
+};
+
+/* idt_init - initialize IDT to each of the entry points in kern/trap/vectors.S */
+void
+idt_init(void) {
+     /* LAB1 YOUR CODE : STEP 2 */
+     /* (1) Where are the entry addrs of each Interrupt Service Routine (ISR)?
+      *     All ISR's entry addrs are stored in __vectors. where is uintptr_t __vectors[] ?
+      *     __vectors[] is in kern/trap/vector.S which is produced by tools/vector.c
+      *     (try "make" command in lab1, then you will find vector.S in kern/trap DIR)
+      *     You can use  "extern uintptr_t __vectors[];" to define this extern variable which will be used later.
+      * (2) Now you should setup the entries of ISR in Interrupt Description Table (IDT).
+      *     Can you see idt[256] in this file? Yes, it's IDT! you can use SETGATE macro to setup each item of IDT
+      * (3) After setup the contents of IDT, you will let CPU know where is the IDT by using 'lidt' instruction.
+      *     You don't know the meaning of this instruction? just google it! and check the libs/x86.h to know more.
+      *     Notice: the argument of lidt is idt_pd. try to find it!
+      */
+     /* LAB5 YOUR CODE */ 
+     //you should update your lab1 code (just add ONE or TWO lines of code), let user app to use syscall to get the service of ucore
+     //so you should setup the syscall interrupt gate in here
+    extern uintptr_t __vectors[];
+    int i;
+    for (i = 0; i < sizeof(idt) / sizeof(struct gatedesc); i ++) {
+        SETGATE(idt[i], 0, GD_KTEXT, __vectors[i], DPL_KERNEL);
+    }
+    SETGATE(idt[T_SYSCALL], 1, GD_KTEXT, __vectors[T_SYSCALL], DPL_USER);
+    lidt(&idt_pd);
+}
+
+static const char *
+trapname(int trapno) {
+    static const char * const excnames[] = {
+        "Divide error",
+        "Debug",
+        "Non-Maskable Interrupt",
+        "Breakpoint",
+        "Overflow",
+        "BOUND Range Exceeded",
+        "Invalid Opcode",
+        "Device Not Available",
+        "Double Fault",
+        "Coprocessor Segment Overrun",
+        "Invalid TSS",
+        "Segment Not Present",
+        "Stack Fault",
+        "General Protection",
+        "Page Fault",
+        "(unknown trap)",
+        "x87 FPU Floating-Point Error",
+        "Alignment Check",
+        "Machine-Check",
+        "SIMD Floating-Point Exception"
+    };
+
+    if (trapno < sizeof(excnames)/sizeof(const char * const)) {
+        return excnames[trapno];
+    }
+    if (trapno >= IRQ_OFFSET && trapno < IRQ_OFFSET + 16) {
+        return "Hardware Interrupt";
+    }
+    return "(unknown trap)";
+}
+
+/* trap_in_kernel - test if trap happened in kernel */
+bool
+trap_in_kernel(struct trapframe *tf) {
+    return (tf->tf_cs == (uint16_t)KERNEL_CS);
+}
+
+static const char *IA32flags[] = {
+    "CF", NULL, "PF", NULL, "AF", NULL, "ZF", "SF",
+    "TF", "IF", "DF", "OF", NULL, NULL, "NT", NULL,
+    "RF", "VM", "AC", "VIF", "VIP", "ID", NULL, NULL,
+};
+
+void
+print_trapframe(struct trapframe *tf) {
+    cprintf("trapframe at %p\n", tf);
+    print_regs(&tf->tf_regs);
+    cprintf("  ds   0x----%04x\n", tf->tf_ds);
+    cprintf("  es   0x----%04x\n", tf->tf_es);
+    cprintf("  fs   0x----%04x\n", tf->tf_fs);
+    cprintf("  gs   0x----%04x\n", tf->tf_gs);
+    cprintf("  trap 0x%08x %s\n", tf->tf_trapno, trapname(tf->tf_trapno));
+    cprintf("  err  0x%08x\n", tf->tf_err);
+    cprintf("  eip  0x%08x\n", tf->tf_eip);
+    cprintf("  cs   0x----%04x\n", tf->tf_cs);
+    cprintf("  flag 0x%08x ", tf->tf_eflags);
+
+    int i, j;
+    for (i = 0, j = 1; i < sizeof(IA32flags) / sizeof(IA32flags[0]); i ++, j <<= 1) {
+        if ((tf->tf_eflags & j) && IA32flags[i] != NULL) {
+            cprintf("%s,", IA32flags[i]);
+        }
+    }
+    cprintf("IOPL=%d\n", (tf->tf_eflags & FL_IOPL_MASK) >> 12);
+
+    if (!trap_in_kernel(tf)) {
+        cprintf("  esp  0x%08x\n", tf->tf_esp);
+        cprintf("  ss   0x----%04x\n", tf->tf_ss);
+    }
+}
+
+void
+print_regs(struct pushregs *regs) {
+    cprintf("  edi  0x%08x\n", regs->reg_edi);
+    cprintf("  esi  0x%08x\n", regs->reg_esi);
+    cprintf("  ebp  0x%08x\n", regs->reg_ebp);
+    cprintf("  oesp 0x%08x\n", regs->reg_oesp);
+    cprintf("  ebx  0x%08x\n", regs->reg_ebx);
+    cprintf("  edx  0x%08x\n", regs->reg_edx);
+    cprintf("  ecx  0x%08x\n", regs->reg_ecx);
+    cprintf("  eax  0x%08x\n", regs->reg_eax);
+}
+
+static inline void
+print_pgfault(struct trapframe *tf) {
+    /* error_code:
+     * bit 0 == 0 means no page found, 1 means protection fault
+     * bit 1 == 0 means read, 1 means write
+     * bit 2 == 0 means kernel, 1 means user
+     * */
+    cprintf("page fault at 0x%08x: %c/%c [%s].\n", rcr2(),
+            (tf->tf_err & 4) ? 'U' : 'K',
+            (tf->tf_err & 2) ? 'W' : 'R',
+            (tf->tf_err & 1) ? "protection fault" : "no page found");
+}
+
+static int
+pgfault_handler(struct trapframe *tf) {
+    extern struct mm_struct *check_mm_struct;
+    if(check_mm_struct !=NULL) { //used for test check_swap
+            print_pgfault(tf);
+        }
+    struct mm_struct *mm;
+    if (check_mm_struct != NULL) {
+        assert(current == idleproc);
+        mm = check_mm_struct;
+    }
+    else {
+        if (current == NULL) {
+            print_trapframe(tf);
+            print_pgfault(tf);
+            panic("unhandled page fault.\n");
+        }
+        mm = current->mm;
+    }
+    return do_pgfault(mm, tf->tf_err, rcr2());
+}
+
+static volatile int in_swap_tick_event = 0;
+extern struct mm_struct *check_mm_struct;
+
+static void
+trap_dispatch(struct trapframe *tf) {
+    char c;
+
+    int ret=0;
+
+    switch (tf->tf_trapno) {
+    case T_PGFLT:  //page fault
+        if ((ret = pgfault_handler(tf)) != 0) {
+            print_trapframe(tf);
+            if (current == NULL) {
+                panic("handle pgfault failed. ret=%d\n", ret);
+            }
+            else {
+                if (trap_in_kernel(tf)) {
+                    panic("handle pgfault failed in kernel mode. ret=%d\n", ret);
+                }
+                cprintf("killed by kernel.\n");
+                panic("handle user mode pgfault failed. ret=%d\n", ret); 
+                do_exit(-E_KILLED);
+            }
+        }
+        break;
+    case T_SYSCALL:
+        syscall();
+        break;
+    case IRQ_OFFSET + IRQ_TIMER:
+#if 0
+    LAB3 : If some page replacement algorithm(such as CLOCK PRA) need tick to change the priority of pages, 
+    then you can add code here. 
+#endif
+        /* LAB1 YOUR CODE : STEP 3 */
+        /* handle the timer interrupt */
+        /* (1) After a timer interrupt, you should record this event using a global variable (increase it), such as ticks in kern/driver/clock.c
+         * (2) Every TICK_NUM cycle, you can print some info using a funciton, such as print_ticks().
+         * (3) Too Simple? Yes, I think so!
+         */
+        /* LAB5 YOUR CODE */
+        /* you should upate you lab1 code (just add ONE or TWO lines of code):
+         *    Every TICK_NUM cycle, you should set current process's current->need_resched = 1
+         */
+        ticks ++;
+        if (ticks % TICK_NUM == 0) {
+            assert(current != NULL);
+            current->need_resched = 1;
+        }
+        break;
+    case IRQ_OFFSET + IRQ_COM1:
+        c = cons_getc();
+        cprintf("serial [%03d] %c\n", c, c);
+        break;
+    case IRQ_OFFSET + IRQ_KBD:
+        c = cons_getc();
+        cprintf("kbd [%03d] %c\n", c, c);
+        break;
+    //LAB1 CHALLENGE 1 : YOUR CODE you should modify below codes.
+    case T_SWITCH_TOU:
+    case T_SWITCH_TOK:
+        panic("T_SWITCH_** ??\n");
+        break;
+    case IRQ_OFFSET + IRQ_IDE1:
+    case IRQ_OFFSET + IRQ_IDE2:
+        /* do nothing */
+        break;
+    default:
+        print_trapframe(tf);
+        if (current != NULL) {
+            cprintf("unhandled trap.\n");
+            do_exit(-E_KILLED);
+        }
+        // in kernel, it must be a mistake
+        panic("unexpected trap in kernel.\n");
+
+    }
+}
+
+/* *
+ * trap - handles or dispatches an exception/interrupt. if and when trap() returns,
+ * the code in kern/trap/trapentry.S restores the old CPU state saved in the
+ * trapframe and then uses the iret instruction to return from the exception.
+ * */
+void
+trap(struct trapframe *tf) {
+    // dispatch based on what type of trap occurred
+    // used for previous projects
+    if (current == NULL) {
+        trap_dispatch(tf);
+    }
+    else {
+        // keep a trapframe chain in stack
+        struct trapframe *otf = current->tf;
+        current->tf = tf;
+    
+        bool in_kernel = trap_in_kernel(tf);
+    
+        trap_dispatch(tf);
+    
+        current->tf = otf;
+        if (!in_kernel) {
+            if (current->flags & PF_EXITING) {
+                do_exit(-E_KILLED);
+            }
+            if (current->need_resched) {
+                schedule();
+            }
+        }
+    }
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.h b/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.h
new file mode 100644
index 0000000..e870a6f
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/trap/trap.h
@@ -0,0 +1,89 @@
+#ifndef __KERN_TRAP_TRAP_H__
+#define __KERN_TRAP_TRAP_H__
+
+#include <defs.h>
+
+/* Trap Numbers */
+
+/* Processor-defined: */
+#define T_DIVIDE                0   // divide error
+#define T_DEBUG                 1   // debug exception
+#define T_NMI                   2   // non-maskable interrupt
+#define T_BRKPT                 3   // breakpoint
+#define T_OFLOW                 4   // overflow
+#define T_BOUND                 5   // bounds check
+#define T_ILLOP                 6   // illegal opcode
+#define T_DEVICE                7   // device not available
+#define T_DBLFLT                8   // double fault
+// #define T_COPROC             9   // reserved (not used since 486)
+#define T_TSS                   10  // invalid task switch segment
+#define T_SEGNP                 11  // segment not present
+#define T_STACK                 12  // stack exception
+#define T_GPFLT                 13  // general protection fault
+#define T_PGFLT                 14  // page fault
+// #define T_RES                15  // reserved
+#define T_FPERR                 16  // floating point error
+#define T_ALIGN                 17  // aligment check
+#define T_MCHK                  18  // machine check
+#define T_SIMDERR               19  // SIMD floating point error
+
+/* Hardware IRQ numbers. We receive these as (IRQ_OFFSET + IRQ_xx) */
+#define IRQ_OFFSET              32  // IRQ 0 corresponds to int IRQ_OFFSET
+
+#define IRQ_TIMER               0
+#define IRQ_KBD                 1
+#define IRQ_COM1                4
+#define IRQ_IDE1                14
+#define IRQ_IDE2                15
+#define IRQ_ERROR               19
+#define IRQ_SPURIOUS            31
+
+/* *
+ * These are arbitrarily chosen, but with care not to overlap
+ * processor defined exceptions or interrupt vectors.
+ * */
+#define T_SWITCH_TOU                120    // user/kernel switch
+#define T_SWITCH_TOK                121    // user/kernel switch
+
+/* registers as pushed by pushal */
+struct pushregs {
+    uint32_t reg_edi;
+    uint32_t reg_esi;
+    uint32_t reg_ebp;
+    uint32_t reg_oesp;          /* Useless */
+    uint32_t reg_ebx;
+    uint32_t reg_edx;
+    uint32_t reg_ecx;
+    uint32_t reg_eax;
+};
+
+struct trapframe {
+    struct pushregs tf_regs;
+    uint16_t tf_gs;
+    uint16_t tf_padding0;
+    uint16_t tf_fs;
+    uint16_t tf_padding1;
+    uint16_t tf_es;
+    uint16_t tf_padding2;
+    uint16_t tf_ds;
+    uint16_t tf_padding3;
+    uint32_t tf_trapno;
+    /* below here defined by x86 hardware */
+    uint32_t tf_err;
+    uintptr_t tf_eip;
+    uint16_t tf_cs;
+    uint16_t tf_padding4;
+    uint32_t tf_eflags;
+    /* below here only when crossing rings, such as from user to kernel */
+    uintptr_t tf_esp;
+    uint16_t tf_ss;
+    uint16_t tf_padding5;
+} __attribute__((packed));
+
+void idt_init(void);
+void print_trapframe(struct trapframe *tf);
+void print_regs(struct pushregs *regs);
+bool trap_in_kernel(struct trapframe *tf);
+
+#endif /* !__KERN_TRAP_TRAP_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/trap/trapentry.S b/related_info/lab5/lab5-spoc-discuss/kern/trap/trapentry.S
new file mode 100644
index 0000000..3565ec8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/trap/trapentry.S
@@ -0,0 +1,49 @@
+#include <memlayout.h>
+
+# vectors.S sends all traps here.
+.text
+.globl __alltraps
+__alltraps:
+    # push registers to build a trap frame
+    # therefore make the stack look like a struct trapframe
+    pushl %ds
+    pushl %es
+    pushl %fs
+    pushl %gs
+    pushal
+
+    # load GD_KDATA into %ds and %es to set up data segments for kernel
+    movl $GD_KDATA, %eax
+    movw %ax, %ds
+    movw %ax, %es
+
+    # push %esp to pass a pointer to the trapframe as an argument to trap()
+    pushl %esp
+
+    # call trap(tf), where tf=%esp
+    call trap
+
+    # pop the pushed stack pointer
+    popl %esp
+
+    # return falls through to trapret...
+.globl __trapret
+__trapret:
+    # restore registers from stack
+    popal
+
+    # restore %ds, %es, %fs and %gs
+    popl %gs
+    popl %fs
+    popl %es
+    popl %ds
+
+    # get rid of the trap number and error code
+    addl $0x8, %esp
+    iret
+
+.globl forkrets
+forkrets:
+    # set stack to this new process's trapframe
+    movl 4(%esp), %esp
+    jmp __trapret
diff --git a/related_info/lab5/lab5-spoc-discuss/kern/trap/vectors.S b/related_info/lab5/lab5-spoc-discuss/kern/trap/vectors.S
new file mode 100644
index 0000000..1d05b4a
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/kern/trap/vectors.S
@@ -0,0 +1,1536 @@
+# handler
+.text
+.globl __alltraps
+.globl vector0
+vector0:
+  pushl $0
+  pushl $0
+  jmp __alltraps
+.globl vector1
+vector1:
+  pushl $0
+  pushl $1
+  jmp __alltraps
+.globl vector2
+vector2:
+  pushl $0
+  pushl $2
+  jmp __alltraps
+.globl vector3
+vector3:
+  pushl $0
+  pushl $3
+  jmp __alltraps
+.globl vector4
+vector4:
+  pushl $0
+  pushl $4
+  jmp __alltraps
+.globl vector5
+vector5:
+  pushl $0
+  pushl $5
+  jmp __alltraps
+.globl vector6
+vector6:
+  pushl $0
+  pushl $6
+  jmp __alltraps
+.globl vector7
+vector7:
+  pushl $0
+  pushl $7
+  jmp __alltraps
+.globl vector8
+vector8:
+  pushl $8
+  jmp __alltraps
+.globl vector9
+vector9:
+  pushl $9
+  jmp __alltraps
+.globl vector10
+vector10:
+  pushl $10
+  jmp __alltraps
+.globl vector11
+vector11:
+  pushl $11
+  jmp __alltraps
+.globl vector12
+vector12:
+  pushl $12
+  jmp __alltraps
+.globl vector13
+vector13:
+  pushl $13
+  jmp __alltraps
+.globl vector14
+vector14:
+  pushl $14
+  jmp __alltraps
+.globl vector15
+vector15:
+  pushl $0
+  pushl $15
+  jmp __alltraps
+.globl vector16
+vector16:
+  pushl $0
+  pushl $16
+  jmp __alltraps
+.globl vector17
+vector17:
+  pushl $17
+  jmp __alltraps
+.globl vector18
+vector18:
+  pushl $0
+  pushl $18
+  jmp __alltraps
+.globl vector19
+vector19:
+  pushl $0
+  pushl $19
+  jmp __alltraps
+.globl vector20
+vector20:
+  pushl $0
+  pushl $20
+  jmp __alltraps
+.globl vector21
+vector21:
+  pushl $0
+  pushl $21
+  jmp __alltraps
+.globl vector22
+vector22:
+  pushl $0
+  pushl $22
+  jmp __alltraps
+.globl vector23
+vector23:
+  pushl $0
+  pushl $23
+  jmp __alltraps
+.globl vector24
+vector24:
+  pushl $0
+  pushl $24
+  jmp __alltraps
+.globl vector25
+vector25:
+  pushl $0
+  pushl $25
+  jmp __alltraps
+.globl vector26
+vector26:
+  pushl $0
+  pushl $26
+  jmp __alltraps
+.globl vector27
+vector27:
+  pushl $0
+  pushl $27
+  jmp __alltraps
+.globl vector28
+vector28:
+  pushl $0
+  pushl $28
+  jmp __alltraps
+.globl vector29
+vector29:
+  pushl $0
+  pushl $29
+  jmp __alltraps
+.globl vector30
+vector30:
+  pushl $0
+  pushl $30
+  jmp __alltraps
+.globl vector31
+vector31:
+  pushl $0
+  pushl $31
+  jmp __alltraps
+.globl vector32
+vector32:
+  pushl $0
+  pushl $32
+  jmp __alltraps
+.globl vector33
+vector33:
+  pushl $0
+  pushl $33
+  jmp __alltraps
+.globl vector34
+vector34:
+  pushl $0
+  pushl $34
+  jmp __alltraps
+.globl vector35
+vector35:
+  pushl $0
+  pushl $35
+  jmp __alltraps
+.globl vector36
+vector36:
+  pushl $0
+  pushl $36
+  jmp __alltraps
+.globl vector37
+vector37:
+  pushl $0
+  pushl $37
+  jmp __alltraps
+.globl vector38
+vector38:
+  pushl $0
+  pushl $38
+  jmp __alltraps
+.globl vector39
+vector39:
+  pushl $0
+  pushl $39
+  jmp __alltraps
+.globl vector40
+vector40:
+  pushl $0
+  pushl $40
+  jmp __alltraps
+.globl vector41
+vector41:
+  pushl $0
+  pushl $41
+  jmp __alltraps
+.globl vector42
+vector42:
+  pushl $0
+  pushl $42
+  jmp __alltraps
+.globl vector43
+vector43:
+  pushl $0
+  pushl $43
+  jmp __alltraps
+.globl vector44
+vector44:
+  pushl $0
+  pushl $44
+  jmp __alltraps
+.globl vector45
+vector45:
+  pushl $0
+  pushl $45
+  jmp __alltraps
+.globl vector46
+vector46:
+  pushl $0
+  pushl $46
+  jmp __alltraps
+.globl vector47
+vector47:
+  pushl $0
+  pushl $47
+  jmp __alltraps
+.globl vector48
+vector48:
+  pushl $0
+  pushl $48
+  jmp __alltraps
+.globl vector49
+vector49:
+  pushl $0
+  pushl $49
+  jmp __alltraps
+.globl vector50
+vector50:
+  pushl $0
+  pushl $50
+  jmp __alltraps
+.globl vector51
+vector51:
+  pushl $0
+  pushl $51
+  jmp __alltraps
+.globl vector52
+vector52:
+  pushl $0
+  pushl $52
+  jmp __alltraps
+.globl vector53
+vector53:
+  pushl $0
+  pushl $53
+  jmp __alltraps
+.globl vector54
+vector54:
+  pushl $0
+  pushl $54
+  jmp __alltraps
+.globl vector55
+vector55:
+  pushl $0
+  pushl $55
+  jmp __alltraps
+.globl vector56
+vector56:
+  pushl $0
+  pushl $56
+  jmp __alltraps
+.globl vector57
+vector57:
+  pushl $0
+  pushl $57
+  jmp __alltraps
+.globl vector58
+vector58:
+  pushl $0
+  pushl $58
+  jmp __alltraps
+.globl vector59
+vector59:
+  pushl $0
+  pushl $59
+  jmp __alltraps
+.globl vector60
+vector60:
+  pushl $0
+  pushl $60
+  jmp __alltraps
+.globl vector61
+vector61:
+  pushl $0
+  pushl $61
+  jmp __alltraps
+.globl vector62
+vector62:
+  pushl $0
+  pushl $62
+  jmp __alltraps
+.globl vector63
+vector63:
+  pushl $0
+  pushl $63
+  jmp __alltraps
+.globl vector64
+vector64:
+  pushl $0
+  pushl $64
+  jmp __alltraps
+.globl vector65
+vector65:
+  pushl $0
+  pushl $65
+  jmp __alltraps
+.globl vector66
+vector66:
+  pushl $0
+  pushl $66
+  jmp __alltraps
+.globl vector67
+vector67:
+  pushl $0
+  pushl $67
+  jmp __alltraps
+.globl vector68
+vector68:
+  pushl $0
+  pushl $68
+  jmp __alltraps
+.globl vector69
+vector69:
+  pushl $0
+  pushl $69
+  jmp __alltraps
+.globl vector70
+vector70:
+  pushl $0
+  pushl $70
+  jmp __alltraps
+.globl vector71
+vector71:
+  pushl $0
+  pushl $71
+  jmp __alltraps
+.globl vector72
+vector72:
+  pushl $0
+  pushl $72
+  jmp __alltraps
+.globl vector73
+vector73:
+  pushl $0
+  pushl $73
+  jmp __alltraps
+.globl vector74
+vector74:
+  pushl $0
+  pushl $74
+  jmp __alltraps
+.globl vector75
+vector75:
+  pushl $0
+  pushl $75
+  jmp __alltraps
+.globl vector76
+vector76:
+  pushl $0
+  pushl $76
+  jmp __alltraps
+.globl vector77
+vector77:
+  pushl $0
+  pushl $77
+  jmp __alltraps
+.globl vector78
+vector78:
+  pushl $0
+  pushl $78
+  jmp __alltraps
+.globl vector79
+vector79:
+  pushl $0
+  pushl $79
+  jmp __alltraps
+.globl vector80
+vector80:
+  pushl $0
+  pushl $80
+  jmp __alltraps
+.globl vector81
+vector81:
+  pushl $0
+  pushl $81
+  jmp __alltraps
+.globl vector82
+vector82:
+  pushl $0
+  pushl $82
+  jmp __alltraps
+.globl vector83
+vector83:
+  pushl $0
+  pushl $83
+  jmp __alltraps
+.globl vector84
+vector84:
+  pushl $0
+  pushl $84
+  jmp __alltraps
+.globl vector85
+vector85:
+  pushl $0
+  pushl $85
+  jmp __alltraps
+.globl vector86
+vector86:
+  pushl $0
+  pushl $86
+  jmp __alltraps
+.globl vector87
+vector87:
+  pushl $0
+  pushl $87
+  jmp __alltraps
+.globl vector88
+vector88:
+  pushl $0
+  pushl $88
+  jmp __alltraps
+.globl vector89
+vector89:
+  pushl $0
+  pushl $89
+  jmp __alltraps
+.globl vector90
+vector90:
+  pushl $0
+  pushl $90
+  jmp __alltraps
+.globl vector91
+vector91:
+  pushl $0
+  pushl $91
+  jmp __alltraps
+.globl vector92
+vector92:
+  pushl $0
+  pushl $92
+  jmp __alltraps
+.globl vector93
+vector93:
+  pushl $0
+  pushl $93
+  jmp __alltraps
+.globl vector94
+vector94:
+  pushl $0
+  pushl $94
+  jmp __alltraps
+.globl vector95
+vector95:
+  pushl $0
+  pushl $95
+  jmp __alltraps
+.globl vector96
+vector96:
+  pushl $0
+  pushl $96
+  jmp __alltraps
+.globl vector97
+vector97:
+  pushl $0
+  pushl $97
+  jmp __alltraps
+.globl vector98
+vector98:
+  pushl $0
+  pushl $98
+  jmp __alltraps
+.globl vector99
+vector99:
+  pushl $0
+  pushl $99
+  jmp __alltraps
+.globl vector100
+vector100:
+  pushl $0
+  pushl $100
+  jmp __alltraps
+.globl vector101
+vector101:
+  pushl $0
+  pushl $101
+  jmp __alltraps
+.globl vector102
+vector102:
+  pushl $0
+  pushl $102
+  jmp __alltraps
+.globl vector103
+vector103:
+  pushl $0
+  pushl $103
+  jmp __alltraps
+.globl vector104
+vector104:
+  pushl $0
+  pushl $104
+  jmp __alltraps
+.globl vector105
+vector105:
+  pushl $0
+  pushl $105
+  jmp __alltraps
+.globl vector106
+vector106:
+  pushl $0
+  pushl $106
+  jmp __alltraps
+.globl vector107
+vector107:
+  pushl $0
+  pushl $107
+  jmp __alltraps
+.globl vector108
+vector108:
+  pushl $0
+  pushl $108
+  jmp __alltraps
+.globl vector109
+vector109:
+  pushl $0
+  pushl $109
+  jmp __alltraps
+.globl vector110
+vector110:
+  pushl $0
+  pushl $110
+  jmp __alltraps
+.globl vector111
+vector111:
+  pushl $0
+  pushl $111
+  jmp __alltraps
+.globl vector112
+vector112:
+  pushl $0
+  pushl $112
+  jmp __alltraps
+.globl vector113
+vector113:
+  pushl $0
+  pushl $113
+  jmp __alltraps
+.globl vector114
+vector114:
+  pushl $0
+  pushl $114
+  jmp __alltraps
+.globl vector115
+vector115:
+  pushl $0
+  pushl $115
+  jmp __alltraps
+.globl vector116
+vector116:
+  pushl $0
+  pushl $116
+  jmp __alltraps
+.globl vector117
+vector117:
+  pushl $0
+  pushl $117
+  jmp __alltraps
+.globl vector118
+vector118:
+  pushl $0
+  pushl $118
+  jmp __alltraps
+.globl vector119
+vector119:
+  pushl $0
+  pushl $119
+  jmp __alltraps
+.globl vector120
+vector120:
+  pushl $0
+  pushl $120
+  jmp __alltraps
+.globl vector121
+vector121:
+  pushl $0
+  pushl $121
+  jmp __alltraps
+.globl vector122
+vector122:
+  pushl $0
+  pushl $122
+  jmp __alltraps
+.globl vector123
+vector123:
+  pushl $0
+  pushl $123
+  jmp __alltraps
+.globl vector124
+vector124:
+  pushl $0
+  pushl $124
+  jmp __alltraps
+.globl vector125
+vector125:
+  pushl $0
+  pushl $125
+  jmp __alltraps
+.globl vector126
+vector126:
+  pushl $0
+  pushl $126
+  jmp __alltraps
+.globl vector127
+vector127:
+  pushl $0
+  pushl $127
+  jmp __alltraps
+.globl vector128
+vector128:
+  pushl $0
+  pushl $128
+  jmp __alltraps
+.globl vector129
+vector129:
+  pushl $0
+  pushl $129
+  jmp __alltraps
+.globl vector130
+vector130:
+  pushl $0
+  pushl $130
+  jmp __alltraps
+.globl vector131
+vector131:
+  pushl $0
+  pushl $131
+  jmp __alltraps
+.globl vector132
+vector132:
+  pushl $0
+  pushl $132
+  jmp __alltraps
+.globl vector133
+vector133:
+  pushl $0
+  pushl $133
+  jmp __alltraps
+.globl vector134
+vector134:
+  pushl $0
+  pushl $134
+  jmp __alltraps
+.globl vector135
+vector135:
+  pushl $0
+  pushl $135
+  jmp __alltraps
+.globl vector136
+vector136:
+  pushl $0
+  pushl $136
+  jmp __alltraps
+.globl vector137
+vector137:
+  pushl $0
+  pushl $137
+  jmp __alltraps
+.globl vector138
+vector138:
+  pushl $0
+  pushl $138
+  jmp __alltraps
+.globl vector139
+vector139:
+  pushl $0
+  pushl $139
+  jmp __alltraps
+.globl vector140
+vector140:
+  pushl $0
+  pushl $140
+  jmp __alltraps
+.globl vector141
+vector141:
+  pushl $0
+  pushl $141
+  jmp __alltraps
+.globl vector142
+vector142:
+  pushl $0
+  pushl $142
+  jmp __alltraps
+.globl vector143
+vector143:
+  pushl $0
+  pushl $143
+  jmp __alltraps
+.globl vector144
+vector144:
+  pushl $0
+  pushl $144
+  jmp __alltraps
+.globl vector145
+vector145:
+  pushl $0
+  pushl $145
+  jmp __alltraps
+.globl vector146
+vector146:
+  pushl $0
+  pushl $146
+  jmp __alltraps
+.globl vector147
+vector147:
+  pushl $0
+  pushl $147
+  jmp __alltraps
+.globl vector148
+vector148:
+  pushl $0
+  pushl $148
+  jmp __alltraps
+.globl vector149
+vector149:
+  pushl $0
+  pushl $149
+  jmp __alltraps
+.globl vector150
+vector150:
+  pushl $0
+  pushl $150
+  jmp __alltraps
+.globl vector151
+vector151:
+  pushl $0
+  pushl $151
+  jmp __alltraps
+.globl vector152
+vector152:
+  pushl $0
+  pushl $152
+  jmp __alltraps
+.globl vector153
+vector153:
+  pushl $0
+  pushl $153
+  jmp __alltraps
+.globl vector154
+vector154:
+  pushl $0
+  pushl $154
+  jmp __alltraps
+.globl vector155
+vector155:
+  pushl $0
+  pushl $155
+  jmp __alltraps
+.globl vector156
+vector156:
+  pushl $0
+  pushl $156
+  jmp __alltraps
+.globl vector157
+vector157:
+  pushl $0
+  pushl $157
+  jmp __alltraps
+.globl vector158
+vector158:
+  pushl $0
+  pushl $158
+  jmp __alltraps
+.globl vector159
+vector159:
+  pushl $0
+  pushl $159
+  jmp __alltraps
+.globl vector160
+vector160:
+  pushl $0
+  pushl $160
+  jmp __alltraps
+.globl vector161
+vector161:
+  pushl $0
+  pushl $161
+  jmp __alltraps
+.globl vector162
+vector162:
+  pushl $0
+  pushl $162
+  jmp __alltraps
+.globl vector163
+vector163:
+  pushl $0
+  pushl $163
+  jmp __alltraps
+.globl vector164
+vector164:
+  pushl $0
+  pushl $164
+  jmp __alltraps
+.globl vector165
+vector165:
+  pushl $0
+  pushl $165
+  jmp __alltraps
+.globl vector166
+vector166:
+  pushl $0
+  pushl $166
+  jmp __alltraps
+.globl vector167
+vector167:
+  pushl $0
+  pushl $167
+  jmp __alltraps
+.globl vector168
+vector168:
+  pushl $0
+  pushl $168
+  jmp __alltraps
+.globl vector169
+vector169:
+  pushl $0
+  pushl $169
+  jmp __alltraps
+.globl vector170
+vector170:
+  pushl $0
+  pushl $170
+  jmp __alltraps
+.globl vector171
+vector171:
+  pushl $0
+  pushl $171
+  jmp __alltraps
+.globl vector172
+vector172:
+  pushl $0
+  pushl $172
+  jmp __alltraps
+.globl vector173
+vector173:
+  pushl $0
+  pushl $173
+  jmp __alltraps
+.globl vector174
+vector174:
+  pushl $0
+  pushl $174
+  jmp __alltraps
+.globl vector175
+vector175:
+  pushl $0
+  pushl $175
+  jmp __alltraps
+.globl vector176
+vector176:
+  pushl $0
+  pushl $176
+  jmp __alltraps
+.globl vector177
+vector177:
+  pushl $0
+  pushl $177
+  jmp __alltraps
+.globl vector178
+vector178:
+  pushl $0
+  pushl $178
+  jmp __alltraps
+.globl vector179
+vector179:
+  pushl $0
+  pushl $179
+  jmp __alltraps
+.globl vector180
+vector180:
+  pushl $0
+  pushl $180
+  jmp __alltraps
+.globl vector181
+vector181:
+  pushl $0
+  pushl $181
+  jmp __alltraps
+.globl vector182
+vector182:
+  pushl $0
+  pushl $182
+  jmp __alltraps
+.globl vector183
+vector183:
+  pushl $0
+  pushl $183
+  jmp __alltraps
+.globl vector184
+vector184:
+  pushl $0
+  pushl $184
+  jmp __alltraps
+.globl vector185
+vector185:
+  pushl $0
+  pushl $185
+  jmp __alltraps
+.globl vector186
+vector186:
+  pushl $0
+  pushl $186
+  jmp __alltraps
+.globl vector187
+vector187:
+  pushl $0
+  pushl $187
+  jmp __alltraps
+.globl vector188
+vector188:
+  pushl $0
+  pushl $188
+  jmp __alltraps
+.globl vector189
+vector189:
+  pushl $0
+  pushl $189
+  jmp __alltraps
+.globl vector190
+vector190:
+  pushl $0
+  pushl $190
+  jmp __alltraps
+.globl vector191
+vector191:
+  pushl $0
+  pushl $191
+  jmp __alltraps
+.globl vector192
+vector192:
+  pushl $0
+  pushl $192
+  jmp __alltraps
+.globl vector193
+vector193:
+  pushl $0
+  pushl $193
+  jmp __alltraps
+.globl vector194
+vector194:
+  pushl $0
+  pushl $194
+  jmp __alltraps
+.globl vector195
+vector195:
+  pushl $0
+  pushl $195
+  jmp __alltraps
+.globl vector196
+vector196:
+  pushl $0
+  pushl $196
+  jmp __alltraps
+.globl vector197
+vector197:
+  pushl $0
+  pushl $197
+  jmp __alltraps
+.globl vector198
+vector198:
+  pushl $0
+  pushl $198
+  jmp __alltraps
+.globl vector199
+vector199:
+  pushl $0
+  pushl $199
+  jmp __alltraps
+.globl vector200
+vector200:
+  pushl $0
+  pushl $200
+  jmp __alltraps
+.globl vector201
+vector201:
+  pushl $0
+  pushl $201
+  jmp __alltraps
+.globl vector202
+vector202:
+  pushl $0
+  pushl $202
+  jmp __alltraps
+.globl vector203
+vector203:
+  pushl $0
+  pushl $203
+  jmp __alltraps
+.globl vector204
+vector204:
+  pushl $0
+  pushl $204
+  jmp __alltraps
+.globl vector205
+vector205:
+  pushl $0
+  pushl $205
+  jmp __alltraps
+.globl vector206
+vector206:
+  pushl $0
+  pushl $206
+  jmp __alltraps
+.globl vector207
+vector207:
+  pushl $0
+  pushl $207
+  jmp __alltraps
+.globl vector208
+vector208:
+  pushl $0
+  pushl $208
+  jmp __alltraps
+.globl vector209
+vector209:
+  pushl $0
+  pushl $209
+  jmp __alltraps
+.globl vector210
+vector210:
+  pushl $0
+  pushl $210
+  jmp __alltraps
+.globl vector211
+vector211:
+  pushl $0
+  pushl $211
+  jmp __alltraps
+.globl vector212
+vector212:
+  pushl $0
+  pushl $212
+  jmp __alltraps
+.globl vector213
+vector213:
+  pushl $0
+  pushl $213
+  jmp __alltraps
+.globl vector214
+vector214:
+  pushl $0
+  pushl $214
+  jmp __alltraps
+.globl vector215
+vector215:
+  pushl $0
+  pushl $215
+  jmp __alltraps
+.globl vector216
+vector216:
+  pushl $0
+  pushl $216
+  jmp __alltraps
+.globl vector217
+vector217:
+  pushl $0
+  pushl $217
+  jmp __alltraps
+.globl vector218
+vector218:
+  pushl $0
+  pushl $218
+  jmp __alltraps
+.globl vector219
+vector219:
+  pushl $0
+  pushl $219
+  jmp __alltraps
+.globl vector220
+vector220:
+  pushl $0
+  pushl $220
+  jmp __alltraps
+.globl vector221
+vector221:
+  pushl $0
+  pushl $221
+  jmp __alltraps
+.globl vector222
+vector222:
+  pushl $0
+  pushl $222
+  jmp __alltraps
+.globl vector223
+vector223:
+  pushl $0
+  pushl $223
+  jmp __alltraps
+.globl vector224
+vector224:
+  pushl $0
+  pushl $224
+  jmp __alltraps
+.globl vector225
+vector225:
+  pushl $0
+  pushl $225
+  jmp __alltraps
+.globl vector226
+vector226:
+  pushl $0
+  pushl $226
+  jmp __alltraps
+.globl vector227
+vector227:
+  pushl $0
+  pushl $227
+  jmp __alltraps
+.globl vector228
+vector228:
+  pushl $0
+  pushl $228
+  jmp __alltraps
+.globl vector229
+vector229:
+  pushl $0
+  pushl $229
+  jmp __alltraps
+.globl vector230
+vector230:
+  pushl $0
+  pushl $230
+  jmp __alltraps
+.globl vector231
+vector231:
+  pushl $0
+  pushl $231
+  jmp __alltraps
+.globl vector232
+vector232:
+  pushl $0
+  pushl $232
+  jmp __alltraps
+.globl vector233
+vector233:
+  pushl $0
+  pushl $233
+  jmp __alltraps
+.globl vector234
+vector234:
+  pushl $0
+  pushl $234
+  jmp __alltraps
+.globl vector235
+vector235:
+  pushl $0
+  pushl $235
+  jmp __alltraps
+.globl vector236
+vector236:
+  pushl $0
+  pushl $236
+  jmp __alltraps
+.globl vector237
+vector237:
+  pushl $0
+  pushl $237
+  jmp __alltraps
+.globl vector238
+vector238:
+  pushl $0
+  pushl $238
+  jmp __alltraps
+.globl vector239
+vector239:
+  pushl $0
+  pushl $239
+  jmp __alltraps
+.globl vector240
+vector240:
+  pushl $0
+  pushl $240
+  jmp __alltraps
+.globl vector241
+vector241:
+  pushl $0
+  pushl $241
+  jmp __alltraps
+.globl vector242
+vector242:
+  pushl $0
+  pushl $242
+  jmp __alltraps
+.globl vector243
+vector243:
+  pushl $0
+  pushl $243
+  jmp __alltraps
+.globl vector244
+vector244:
+  pushl $0
+  pushl $244
+  jmp __alltraps
+.globl vector245
+vector245:
+  pushl $0
+  pushl $245
+  jmp __alltraps
+.globl vector246
+vector246:
+  pushl $0
+  pushl $246
+  jmp __alltraps
+.globl vector247
+vector247:
+  pushl $0
+  pushl $247
+  jmp __alltraps
+.globl vector248
+vector248:
+  pushl $0
+  pushl $248
+  jmp __alltraps
+.globl vector249
+vector249:
+  pushl $0
+  pushl $249
+  jmp __alltraps
+.globl vector250
+vector250:
+  pushl $0
+  pushl $250
+  jmp __alltraps
+.globl vector251
+vector251:
+  pushl $0
+  pushl $251
+  jmp __alltraps
+.globl vector252
+vector252:
+  pushl $0
+  pushl $252
+  jmp __alltraps
+.globl vector253
+vector253:
+  pushl $0
+  pushl $253
+  jmp __alltraps
+.globl vector254
+vector254:
+  pushl $0
+  pushl $254
+  jmp __alltraps
+.globl vector255
+vector255:
+  pushl $0
+  pushl $255
+  jmp __alltraps
+
+# vector table
+.data
+.globl __vectors
+__vectors:
+  .long vector0
+  .long vector1
+  .long vector2
+  .long vector3
+  .long vector4
+  .long vector5
+  .long vector6
+  .long vector7
+  .long vector8
+  .long vector9
+  .long vector10
+  .long vector11
+  .long vector12
+  .long vector13
+  .long vector14
+  .long vector15
+  .long vector16
+  .long vector17
+  .long vector18
+  .long vector19
+  .long vector20
+  .long vector21
+  .long vector22
+  .long vector23
+  .long vector24
+  .long vector25
+  .long vector26
+  .long vector27
+  .long vector28
+  .long vector29
+  .long vector30
+  .long vector31
+  .long vector32
+  .long vector33
+  .long vector34
+  .long vector35
+  .long vector36
+  .long vector37
+  .long vector38
+  .long vector39
+  .long vector40
+  .long vector41
+  .long vector42
+  .long vector43
+  .long vector44
+  .long vector45
+  .long vector46
+  .long vector47
+  .long vector48
+  .long vector49
+  .long vector50
+  .long vector51
+  .long vector52
+  .long vector53
+  .long vector54
+  .long vector55
+  .long vector56
+  .long vector57
+  .long vector58
+  .long vector59
+  .long vector60
+  .long vector61
+  .long vector62
+  .long vector63
+  .long vector64
+  .long vector65
+  .long vector66
+  .long vector67
+  .long vector68
+  .long vector69
+  .long vector70
+  .long vector71
+  .long vector72
+  .long vector73
+  .long vector74
+  .long vector75
+  .long vector76
+  .long vector77
+  .long vector78
+  .long vector79
+  .long vector80
+  .long vector81
+  .long vector82
+  .long vector83
+  .long vector84
+  .long vector85
+  .long vector86
+  .long vector87
+  .long vector88
+  .long vector89
+  .long vector90
+  .long vector91
+  .long vector92
+  .long vector93
+  .long vector94
+  .long vector95
+  .long vector96
+  .long vector97
+  .long vector98
+  .long vector99
+  .long vector100
+  .long vector101
+  .long vector102
+  .long vector103
+  .long vector104
+  .long vector105
+  .long vector106
+  .long vector107
+  .long vector108
+  .long vector109
+  .long vector110
+  .long vector111
+  .long vector112
+  .long vector113
+  .long vector114
+  .long vector115
+  .long vector116
+  .long vector117
+  .long vector118
+  .long vector119
+  .long vector120
+  .long vector121
+  .long vector122
+  .long vector123
+  .long vector124
+  .long vector125
+  .long vector126
+  .long vector127
+  .long vector128
+  .long vector129
+  .long vector130
+  .long vector131
+  .long vector132
+  .long vector133
+  .long vector134
+  .long vector135
+  .long vector136
+  .long vector137
+  .long vector138
+  .long vector139
+  .long vector140
+  .long vector141
+  .long vector142
+  .long vector143
+  .long vector144
+  .long vector145
+  .long vector146
+  .long vector147
+  .long vector148
+  .long vector149
+  .long vector150
+  .long vector151
+  .long vector152
+  .long vector153
+  .long vector154
+  .long vector155
+  .long vector156
+  .long vector157
+  .long vector158
+  .long vector159
+  .long vector160
+  .long vector161
+  .long vector162
+  .long vector163
+  .long vector164
+  .long vector165
+  .long vector166
+  .long vector167
+  .long vector168
+  .long vector169
+  .long vector170
+  .long vector171
+  .long vector172
+  .long vector173
+  .long vector174
+  .long vector175
+  .long vector176
+  .long vector177
+  .long vector178
+  .long vector179
+  .long vector180
+  .long vector181
+  .long vector182
+  .long vector183
+  .long vector184
+  .long vector185
+  .long vector186
+  .long vector187
+  .long vector188
+  .long vector189
+  .long vector190
+  .long vector191
+  .long vector192
+  .long vector193
+  .long vector194
+  .long vector195
+  .long vector196
+  .long vector197
+  .long vector198
+  .long vector199
+  .long vector200
+  .long vector201
+  .long vector202
+  .long vector203
+  .long vector204
+  .long vector205
+  .long vector206
+  .long vector207
+  .long vector208
+  .long vector209
+  .long vector210
+  .long vector211
+  .long vector212
+  .long vector213
+  .long vector214
+  .long vector215
+  .long vector216
+  .long vector217
+  .long vector218
+  .long vector219
+  .long vector220
+  .long vector221
+  .long vector222
+  .long vector223
+  .long vector224
+  .long vector225
+  .long vector226
+  .long vector227
+  .long vector228
+  .long vector229
+  .long vector230
+  .long vector231
+  .long vector232
+  .long vector233
+  .long vector234
+  .long vector235
+  .long vector236
+  .long vector237
+  .long vector238
+  .long vector239
+  .long vector240
+  .long vector241
+  .long vector242
+  .long vector243
+  .long vector244
+  .long vector245
+  .long vector246
+  .long vector247
+  .long vector248
+  .long vector249
+  .long vector250
+  .long vector251
+  .long vector252
+  .long vector253
+  .long vector254
+  .long vector255
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/atomic.h b/related_info/lab5/lab5-spoc-discuss/libs/atomic.h
new file mode 100644
index 0000000..e8f317b
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/atomic.h
@@ -0,0 +1,81 @@
+#ifndef __LIBS_ATOMIC_H__
+#define __LIBS_ATOMIC_H__
+
+/* Atomic operations that C can't guarantee us. Useful for resource counting etc.. */
+
+static inline void set_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline void clear_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline void change_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline bool test_bit(int nr, volatile void *addr) __attribute__((always_inline));
+
+/* *
+ * set_bit - Atomically set a bit in memory
+ * @nr:     the bit to set
+ * @addr:   the address to start counting from
+ *
+ * Note that @nr may be almost arbitrarily large; this function is not
+ * restricted to acting on a single-word quantity.
+ * */
+static inline void
+set_bit(int nr, volatile void *addr) {
+    asm volatile ("btsl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * clear_bit - Atomically clears a bit in memory
+ * @nr:     the bit to clear
+ * @addr:   the address to start counting from
+ * */
+static inline void
+clear_bit(int nr, volatile void *addr) {
+    asm volatile ("btrl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * change_bit - Atomically toggle a bit in memory
+ * @nr:     the bit to change
+ * @addr:   the address to start counting from
+ * */
+static inline void
+change_bit(int nr, volatile void *addr) {
+    asm volatile ("btcl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * test_bit - Determine whether a bit is set
+ * @nr:     the bit to test
+ * @addr:   the address to count from
+ * */
+static inline bool
+test_bit(int nr, volatile void *addr) {
+    int oldbit;
+    asm volatile ("btl %2, %1; sbbl %0,%0" : "=r" (oldbit) : "m" (*(volatile long *)addr), "Ir" (nr));
+    return oldbit != 0;
+}
+
+/* *
+ * test_and_set_bit - Atomically set a bit and return its old value
+ * @nr:     the bit to set
+ * @addr:   the address to count from
+ * */
+static inline bool
+test_and_set_bit(int nr, volatile void *addr) {
+    int oldbit;
+    asm volatile ("btsl %2, %1; sbbl %0, %0" : "=r" (oldbit), "=m" (*(volatile long *)addr) : "Ir" (nr) : "memory");
+    return oldbit != 0;
+}
+
+/* *
+ * test_and_clear_bit - Atomically clear a bit and return its old value
+ * @nr:     the bit to clear
+ * @addr:   the address to count from
+ * */
+static inline bool
+test_and_clear_bit(int nr, volatile void *addr) {
+    int oldbit;
+    asm volatile ("btrl %2, %1; sbbl %0, %0" : "=r" (oldbit), "=m" (*(volatile long *)addr) : "Ir" (nr) : "memory");
+    return oldbit != 0;
+}
+
+#endif /* !__LIBS_ATOMIC_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/defs.h b/related_info/lab5/lab5-spoc-discuss/libs/defs.h
new file mode 100644
index 0000000..88f280e
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/defs.h
@@ -0,0 +1,68 @@
+#ifndef __LIBS_DEFS_H__
+#define __LIBS_DEFS_H__
+
+#ifndef NULL
+#define NULL ((void *)0)
+#endif
+
+#define __always_inline inline __attribute__((always_inline))
+#define __noinline __attribute__((noinline))
+#define __noreturn __attribute__((noreturn))
+
+/* Represents true-or-false values */
+typedef int bool;
+
+/* Explicitly-sized versions of integer types */
+typedef char int8_t;
+typedef unsigned char uint8_t;
+typedef short int16_t;
+typedef unsigned short uint16_t;
+typedef int int32_t;
+typedef unsigned int uint32_t;
+typedef long long int64_t;
+typedef unsigned long long uint64_t;
+
+/* *
+ * Pointers and addresses are 32 bits long.
+ * We use pointer types to represent addresses,
+ * uintptr_t to represent the numerical values of addresses.
+ * */
+typedef int32_t intptr_t;
+typedef uint32_t uintptr_t;
+
+/* size_t is used for memory object sizes */
+typedef uintptr_t size_t;
+
+/* used for page numbers */
+typedef size_t ppn_t;
+
+/* *
+ * Rounding operations (efficient when n is a power of 2)
+ * Round down to the nearest multiple of n
+ * */
+#define ROUNDDOWN(a, n) ({                                          \
+            size_t __a = (size_t)(a);                               \
+            (typeof(a))(__a - __a % (n));                           \
+        })
+
+/* Round up to the nearest multiple of n */
+#define ROUNDUP(a, n) ({                                            \
+            size_t __n = (size_t)(n);                               \
+            (typeof(a))(ROUNDDOWN((size_t)(a) + __n - 1, __n));     \
+        })
+
+/* Return the offset of 'member' relative to the beginning of a struct type */
+#define offsetof(type, member)                                      \
+    ((size_t)(&((type *)0)->member))
+
+/* *
+ * to_struct - get the struct from a ptr
+ * @ptr:    a struct pointer of member
+ * @type:   the type of the struct this is embedded in
+ * @member: the name of the member within the struct
+ * */
+#define to_struct(ptr, type, member)                               \
+    ((type *)((char *)(ptr) - offsetof(type, member)))
+
+#endif /* !__LIBS_DEFS_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/elf.h b/related_info/lab5/lab5-spoc-discuss/libs/elf.h
new file mode 100644
index 0000000..8678f10
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/elf.h
@@ -0,0 +1,48 @@
+#ifndef __LIBS_ELF_H__
+#define __LIBS_ELF_H__
+
+#include <defs.h>
+
+#define ELF_MAGIC   0x464C457FU         // "\x7FELF" in little endian
+
+/* file header */
+struct elfhdr {
+    uint32_t e_magic;     // must equal ELF_MAGIC
+    uint8_t e_elf[12];
+    uint16_t e_type;      // 1=relocatable, 2=executable, 3=shared object, 4=core image
+    uint16_t e_machine;   // 3=x86, 4=68K, etc.
+    uint32_t e_version;   // file version, always 1
+    uint32_t e_entry;     // entry point if executable
+    uint32_t e_phoff;     // file position of program header or 0
+    uint32_t e_shoff;     // file position of section header or 0
+    uint32_t e_flags;     // architecture-specific flags, usually 0
+    uint16_t e_ehsize;    // size of this elf header
+    uint16_t e_phentsize; // size of an entry in program header
+    uint16_t e_phnum;     // number of entries in program header or 0
+    uint16_t e_shentsize; // size of an entry in section header
+    uint16_t e_shnum;     // number of entries in section header or 0
+    uint16_t e_shstrndx;  // section number that contains section name strings
+};
+
+/* program section header */
+struct proghdr {
+    uint32_t p_type;   // loadable code or data, dynamic linking info,etc.
+    uint32_t p_offset; // file offset of segment
+    uint32_t p_va;     // virtual address to map segment
+    uint32_t p_pa;     // physical address, not used
+    uint32_t p_filesz; // size of segment in file
+    uint32_t p_memsz;  // size of segment in memory (bigger if contains bss）
+    uint32_t p_flags;  // read/write/execute bits
+    uint32_t p_align;  // required alignment, invariably hardware page size
+};
+
+/* values for Proghdr::p_type */
+#define ELF_PT_LOAD                     1
+
+/* flag bits for Proghdr::p_flags */
+#define ELF_PF_X                        1
+#define ELF_PF_W                        2
+#define ELF_PF_R                        4
+
+#endif /* !__LIBS_ELF_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/error.h b/related_info/lab5/lab5-spoc-discuss/libs/error.h
new file mode 100644
index 0000000..ddad593
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/error.h
@@ -0,0 +1,33 @@
+#ifndef __LIBS_ERROR_H__
+#define __LIBS_ERROR_H__
+
+/* kernel error codes -- keep in sync with list in lib/printfmt.c */
+#define E_UNSPECIFIED       1   // Unspecified or unknown problem
+#define E_BAD_PROC          2   // Process doesn't exist or otherwise
+#define E_INVAL             3   // Invalid parameter
+#define E_NO_MEM            4   // Request failed due to memory shortage
+#define E_NO_FREE_PROC      5   // Attempt to create a new process beyond
+#define E_FAULT             6   // Memory fault
+#define E_SWAP_FAULT        7   // SWAP READ/WRITE fault
+#define E_INVAL_ELF         8   // Invalid elf file
+#define E_KILLED            9   // Process is killed
+#define E_PANIC             10  // Panic Failure
+#define E_TIMEOUT           11  // Timeout
+#define E_TOO_BIG           12  // Argument is Too Big
+#define E_NO_DEV            13  // No such Device
+#define E_NA_DEV            14  // Device Not Available
+#define E_BUSY              15  // Device/File is Busy
+#define E_NOENT             16  // No Such File or Directory
+#define E_ISDIR             17  // Is a Directory
+#define E_NOTDIR            18  // Not a Directory
+#define E_XDEV              19  // Cross Device-Link
+#define E_UNIMP             20  // Unimplemented Feature
+#define E_SEEK              21  // Illegal Seek
+#define E_MAX_OPEN          22  // Too Many Files are Open
+#define E_EXISTS            23  // File/Directory Already Exists
+#define E_NOTEMPTY          24  // Directory is Not Empty
+/* the maximum allowed */
+#define MAXERROR            24
+
+#endif /* !__LIBS_ERROR_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/hash.c b/related_info/lab5/lab5-spoc-discuss/libs/hash.c
new file mode 100644
index 0000000..61bcd88
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/hash.c
@@ -0,0 +1,18 @@
+#include <stdlib.h>
+
+/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
+#define GOLDEN_RATIO_PRIME_32       0x9e370001UL
+
+/* *
+ * hash32 - generate a hash value in the range [0, 2^@bits - 1]
+ * @val:    the input value
+ * @bits:   the number of bits in a return value
+ *
+ * High bits are more random, so we use them.
+ * */
+uint32_t
+hash32(uint32_t val, unsigned int bits) {
+    uint32_t hash = val * GOLDEN_RATIO_PRIME_32;
+    return (hash >> (32 - bits));
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/list.h b/related_info/lab5/lab5-spoc-discuss/libs/list.h
new file mode 100644
index 0000000..3dbf772
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/list.h
@@ -0,0 +1,163 @@
+#ifndef __LIBS_LIST_H__
+#define __LIBS_LIST_H__
+
+#ifndef __ASSEMBLER__
+
+#include <defs.h>
+
+/* *
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when manipulating
+ * whole lists rather than single entries, as sometimes we already know
+ * the next/prev entries and we can generate better code by using them
+ * directly rather than using the generic single-entry routines.
+ * */
+
+struct list_entry {
+    struct list_entry *prev, *next;
+};
+
+typedef struct list_entry list_entry_t;
+
+static inline void list_init(list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add_before(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add_after(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_del(list_entry_t *listelm) __attribute__((always_inline));
+static inline void list_del_init(list_entry_t *listelm) __attribute__((always_inline));
+static inline bool list_empty(list_entry_t *list) __attribute__((always_inline));
+static inline list_entry_t *list_next(list_entry_t *listelm) __attribute__((always_inline));
+static inline list_entry_t *list_prev(list_entry_t *listelm) __attribute__((always_inline));
+
+static inline void __list_add(list_entry_t *elm, list_entry_t *prev, list_entry_t *next) __attribute__((always_inline));
+static inline void __list_del(list_entry_t *prev, list_entry_t *next) __attribute__((always_inline));
+
+/* *
+ * list_init - initialize a new entry
+ * @elm:        new entry to be initialized
+ * */
+static inline void
+list_init(list_entry_t *elm) {
+    elm->prev = elm->next = elm;
+}
+
+/* *
+ * list_add - add a new entry
+ * @listelm:    list head to add after
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *after* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add(list_entry_t *listelm, list_entry_t *elm) {
+    list_add_after(listelm, elm);
+}
+
+/* *
+ * list_add_before - add a new entry
+ * @listelm:    list head to add before
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *before* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add_before(list_entry_t *listelm, list_entry_t *elm) {
+    __list_add(elm, listelm->prev, listelm);
+}
+
+/* *
+ * list_add_after - add a new entry
+ * @listelm:    list head to add after
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *after* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add_after(list_entry_t *listelm, list_entry_t *elm) {
+    __list_add(elm, listelm, listelm->next);
+}
+
+/* *
+ * list_del - deletes entry from list
+ * @listelm:    the element to delete from the list
+ *
+ * Note: list_empty() on @listelm does not return true after this, the entry is
+ * in an undefined state.
+ * */
+static inline void
+list_del(list_entry_t *listelm) {
+    __list_del(listelm->prev, listelm->next);
+}
+
+/* *
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @listelm:    the element to delete from the list.
+ *
+ * Note: list_empty() on @listelm returns true after this.
+ * */
+static inline void
+list_del_init(list_entry_t *listelm) {
+    list_del(listelm);
+    list_init(listelm);
+}
+
+/* *
+ * list_empty - tests whether a list is empty
+ * @list:       the list to test.
+ * */
+static inline bool
+list_empty(list_entry_t *list) {
+    return list->next == list;
+}
+
+/* *
+ * list_next - get the next entry
+ * @listelm:    the list head
+ **/
+static inline list_entry_t *
+list_next(list_entry_t *listelm) {
+    return listelm->next;
+}
+
+/* *
+ * list_prev - get the previous entry
+ * @listelm:    the list head
+ **/
+static inline list_entry_t *
+list_prev(list_entry_t *listelm) {
+    return listelm->prev;
+}
+
+/* *
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ * */
+static inline void
+__list_add(list_entry_t *elm, list_entry_t *prev, list_entry_t *next) {
+    prev->next = next->prev = elm;
+    elm->next = next;
+    elm->prev = prev;
+}
+
+/* *
+ * Delete a list entry by making the prev/next entries point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ * */
+static inline void
+__list_del(list_entry_t *prev, list_entry_t *next) {
+    prev->next = next;
+    next->prev = prev;
+}
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* !__LIBS_LIST_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/printfmt.c b/related_info/lab5/lab5-spoc-discuss/libs/printfmt.c
new file mode 100644
index 0000000..a666a52
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/printfmt.c
@@ -0,0 +1,343 @@
+#include <defs.h>
+#include <x86.h>
+#include <error.h>
+#include <stdio.h>
+#include <string.h>
+
+/* *
+ * Space or zero padding and a field width are supported for the numeric
+ * formats only.
+ *
+ * The special format %e takes an integer error code
+ * and prints a string describing the error.
+ * The integer may be positive or negative,
+ * so that -E_NO_MEM and E_NO_MEM are equivalent.
+ * */
+
+static const char * const error_string[MAXERROR + 1] = {
+    [0]                     NULL,
+    [E_UNSPECIFIED]         "unspecified error",
+    [E_BAD_PROC]            "bad process",
+    [E_INVAL]               "invalid parameter",
+    [E_NO_MEM]              "out of memory",
+    [E_NO_FREE_PROC]        "out of processes",
+    [E_FAULT]               "segmentation fault",
+    [E_INVAL_ELF]           "invalid elf file",
+    [E_KILLED]              "process is killed",
+    [E_PANIC]               "panic failure",
+};
+
+/* *
+ * printnum - print a number (base <= 16) in reverse order
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @num:        the number will be printed
+ * @base:       base for print, must be in [1, 16]
+ * @width:      maximum number of digits, if the actual width is less than @width, use @padc instead
+ * @padc:       character that padded on the left if the actual width is less than @width
+ * */
+static void
+printnum(void (*putch)(int, void*), void *putdat,
+        unsigned long long num, unsigned base, int width, int padc) {
+    unsigned long long result = num;
+    unsigned mod = do_div(result, base);
+
+    // first recursively print all preceding (more significant) digits
+    if (num >= base) {
+        printnum(putch, putdat, result, base, width - 1, padc);
+    } else {
+        // print any needed pad characters before first digit
+        while (-- width > 0)
+            putch(padc, putdat);
+    }
+    // then print this (the least significant) digit
+    putch("0123456789abcdef"[mod], putdat);
+}
+
+/* *
+ * getuint - get an unsigned int of various possible sizes from a varargs list
+ * @ap:         a varargs list pointer
+ * @lflag:      determines the size of the vararg that @ap points to
+ * */
+static unsigned long long
+getuint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, unsigned long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, unsigned long);
+    }
+    else {
+        return va_arg(*ap, unsigned int);
+    }
+}
+
+/* *
+ * getint - same as getuint but signed, we can't use getuint because of sign extension
+ * @ap:         a varargs list pointer
+ * @lflag:      determines the size of the vararg that @ap points to
+ * */
+static long long
+getint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, long);
+    }
+    else {
+        return va_arg(*ap, int);
+    }
+}
+
+/* *
+ * printfmt - format a string and print it by using putch
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @fmt:        the format string to use
+ * */
+void
+printfmt(void (*putch)(int, void*), void *putdat, const char *fmt, ...) {
+    va_list ap;
+
+    va_start(ap, fmt);
+    vprintfmt(putch, putdat, fmt, ap);
+    va_end(ap);
+}
+
+/* *
+ * vprintfmt - format a string and print it by using putch, it's called with a va_list
+ * instead of a variable number of arguments
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @fmt:        the format string to use
+ * @ap:         arguments for the format string
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want printfmt() instead.
+ * */
+void
+vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap) {
+    register const char *p;
+    register int ch, err;
+    unsigned long long num;
+    int base, width, precision, lflag, altflag;
+
+    while (1) {
+        while ((ch = *(unsigned char *)fmt ++) != '%') {
+            if (ch == '\0') {
+                return;
+            }
+            putch(ch, putdat);
+        }
+
+        // Process a %-escape sequence
+        char padc = ' ';
+        width = precision = -1;
+        lflag = altflag = 0;
+
+    reswitch:
+        switch (ch = *(unsigned char *)fmt ++) {
+
+        // flag to pad on the right
+        case '-':
+            padc = '-';
+            goto reswitch;
+
+        // flag to pad with 0's instead of spaces
+        case '0':
+            padc = '0';
+            goto reswitch;
+
+        // width field
+        case '1' ... '9':
+            for (precision = 0; ; ++ fmt) {
+                precision = precision * 10 + ch - '0';
+                ch = *fmt;
+                if (ch < '0' || ch > '9') {
+                    break;
+                }
+            }
+            goto process_precision;
+
+        case '*':
+            precision = va_arg(ap, int);
+            goto process_precision;
+
+        case '.':
+            if (width < 0)
+                width = 0;
+            goto reswitch;
+
+        case '#':
+            altflag = 1;
+            goto reswitch;
+
+        process_precision:
+            if (width < 0)
+                width = precision, precision = -1;
+            goto reswitch;
+
+        // long flag (doubled for long long)
+        case 'l':
+            lflag ++;
+            goto reswitch;
+
+        // character
+        case 'c':
+            putch(va_arg(ap, int), putdat);
+            break;
+
+        // error message
+        case 'e':
+            err = va_arg(ap, int);
+            if (err < 0) {
+                err = -err;
+            }
+            if (err > MAXERROR || (p = error_string[err]) == NULL) {
+                printfmt(putch, putdat, "error %d", err);
+            }
+            else {
+                printfmt(putch, putdat, "%s", p);
+            }
+            break;
+
+        // string
+        case 's':
+            if ((p = va_arg(ap, char *)) == NULL) {
+                p = "(null)";
+            }
+            if (width > 0 && padc != '-') {
+                for (width -= strnlen(p, precision); width > 0; width --) {
+                    putch(padc, putdat);
+                }
+            }
+            for (; (ch = *p ++) != '\0' && (precision < 0 || -- precision >= 0); width --) {
+                if (altflag && (ch < ' ' || ch > '~')) {
+                    putch('?', putdat);
+                }
+                else {
+                    putch(ch, putdat);
+                }
+            }
+            for (; width > 0; width --) {
+                putch(' ', putdat);
+            }
+            break;
+
+        // (signed) decimal
+        case 'd':
+            num = getint(&ap, lflag);
+            if ((long long)num < 0) {
+                putch('-', putdat);
+                num = -(long long)num;
+            }
+            base = 10;
+            goto number;
+
+        // unsigned decimal
+        case 'u':
+            num = getuint(&ap, lflag);
+            base = 10;
+            goto number;
+
+        // (unsigned) octal
+        case 'o':
+            num = getuint(&ap, lflag);
+            base = 8;
+            goto number;
+
+        // pointer
+        case 'p':
+            putch('0', putdat);
+            putch('x', putdat);
+            num = (unsigned long long)(uintptr_t)va_arg(ap, void *);
+            base = 16;
+            goto number;
+
+        // (unsigned) hexadecimal
+        case 'x':
+            num = getuint(&ap, lflag);
+            base = 16;
+        number:
+            printnum(putch, putdat, num, base, width, padc);
+            break;
+
+        // escaped '%' character
+        case '%':
+            putch(ch, putdat);
+            break;
+
+        // unrecognized escape sequence - just print it literally
+        default:
+            putch('%', putdat);
+            for (fmt --; fmt[-1] != '%'; fmt --)
+                /* do nothing */;
+            break;
+        }
+    }
+}
+
+/* sprintbuf is used to save enough information of a buffer */
+struct sprintbuf {
+    char *buf;          // address pointer points to the first unused memory
+    char *ebuf;         // points the end of the buffer
+    int cnt;            // the number of characters that have been placed in this buffer
+};
+
+/* *
+ * sprintputch - 'print' a single character in a buffer
+ * @ch:         the character will be printed
+ * @b:          the buffer to place the character @ch
+ * */
+static void
+sprintputch(int ch, struct sprintbuf *b) {
+    b->cnt ++;
+    if (b->buf < b->ebuf) {
+        *b->buf ++ = ch;
+    }
+}
+
+/* *
+ * snprintf - format a string and place it in a buffer
+ * @str:        the buffer to place the result into
+ * @size:       the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * */
+int
+snprintf(char *str, size_t size, const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vsnprintf(str, size, fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* *
+ * vsnprintf - format a string and place it in a buffer, it's called with a va_list
+ * instead of a variable number of arguments
+ * @str:        the buffer to place the result into
+ * @size:       the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * @ap:         arguments for the format string
+ *
+ * The return value is the number of characters which would be generated for the
+ * given input, excluding the trailing '\0'.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want snprintf() instead.
+ * */
+int
+vsnprintf(char *str, size_t size, const char *fmt, va_list ap) {
+    struct sprintbuf b = {str, str + size - 1, 0};
+    if (str == NULL || b.buf > b.ebuf) {
+        return -E_INVAL;
+    }
+    // print the string to the buffer
+    vprintfmt((void*)sprintputch, &b, fmt, ap);
+    // null terminate the buffer
+    *b.buf = '\0';
+    return b.cnt;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/rand.c b/related_info/lab5/lab5-spoc-discuss/libs/rand.c
new file mode 100644
index 0000000..2a2c4e7
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/rand.c
@@ -0,0 +1,26 @@
+#include <x86.h>
+#include <stdlib.h>
+
+static unsigned long long next = 1;
+
+/* *
+ * rand - returns a pseudo-random integer
+ *
+ * The rand() function return a value in the range [0, RAND_MAX].
+ * */
+int
+rand(void) {
+    next = (next * 0x5DEECE66DLL + 0xBLL) & ((1LL << 48) - 1);
+    unsigned long long result = (next >> 12);
+    return (int)do_div(result, RAND_MAX + 1);
+}
+
+/* *
+ * srand - seed the random number generator with the given number
+ * @seed:   the required seed number
+ * */
+void
+srand(unsigned int seed) {
+    next = seed;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/stdarg.h b/related_info/lab5/lab5-spoc-discuss/libs/stdarg.h
new file mode 100644
index 0000000..f6e0758
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/stdarg.h
@@ -0,0 +1,12 @@
+#ifndef __LIBS_STDARG_H__
+#define __LIBS_STDARG_H__
+
+/* compiler provides size of save area */
+typedef __builtin_va_list va_list;
+
+#define va_start(ap, last)              (__builtin_va_start(ap, last))
+#define va_arg(ap, type)                (__builtin_va_arg(ap, type))
+#define va_end(ap)                      /*nothing*/
+
+#endif /* !__LIBS_STDARG_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/stdio.h b/related_info/lab5/lab5-spoc-discuss/libs/stdio.h
new file mode 100644
index 0000000..41e8b41
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/stdio.h
@@ -0,0 +1,24 @@
+#ifndef __LIBS_STDIO_H__
+#define __LIBS_STDIO_H__
+
+#include <defs.h>
+#include <stdarg.h>
+
+/* kern/libs/stdio.c */
+int cprintf(const char *fmt, ...);
+int vcprintf(const char *fmt, va_list ap);
+void cputchar(int c);
+int cputs(const char *str);
+int getchar(void);
+
+/* kern/libs/readline.c */
+char *readline(const char *prompt);
+
+/* libs/printfmt.c */
+void printfmt(void (*putch)(int, void *), void *putdat, const char *fmt, ...);
+void vprintfmt(void (*putch)(int, void *), void *putdat, const char *fmt, va_list ap);
+int snprintf(char *str, size_t size, const char *fmt, ...);
+int vsnprintf(char *str, size_t size, const char *fmt, va_list ap);
+
+#endif /* !__LIBS_STDIO_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/stdlib.h b/related_info/lab5/lab5-spoc-discuss/libs/stdlib.h
new file mode 100644
index 0000000..51878ef
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/stdlib.h
@@ -0,0 +1,17 @@
+#ifndef __LIBS_STDLIB_H__
+#define __LIBS_STDLIB_H__
+
+#include <defs.h>
+
+/* the largest number rand will return */
+#define RAND_MAX    2147483647UL
+
+/* libs/rand.c */
+int rand(void);
+void srand(unsigned int seed);
+
+/* libs/hash.c */
+uint32_t hash32(uint32_t val, unsigned int bits);
+
+#endif /* !__LIBS_RAND_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/string.c b/related_info/lab5/lab5-spoc-discuss/libs/string.c
new file mode 100644
index 0000000..bcf1b1c
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/string.c
@@ -0,0 +1,367 @@
+#include <string.h>
+#include <x86.h>
+
+/* *
+ * strlen - calculate the length of the string @s, not including
+ * the terminating '\0' character.
+ * @s:      the input string
+ *
+ * The strlen() function returns the length of string @s.
+ * */
+size_t
+strlen(const char *s) {
+    size_t cnt = 0;
+    while (*s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strnlen - calculate the length of the string @s, not including
+ * the terminating '\0' char acter, but at most @len.
+ * @s:      the input string
+ * @len:    the max-length that function will scan
+ *
+ * Note that, this function looks only at the first @len characters
+ * at @s, and never beyond @s + @len.
+ *
+ * The return value is strlen(s), if that is less than @len, or
+ * @len if there is no '\0' character among the first @len characters
+ * pointed by @s.
+ * */
+size_t
+strnlen(const char *s, size_t len) {
+    size_t cnt = 0;
+    while (cnt < len && *s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strcpy - copies the string pointed by @src into the array pointed by @dst,
+ * including the terminating null character.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ *
+ * The return value is @dst.
+ *
+ * To avoid overflows, the size of array pointed by @dst should be long enough to
+ * contain the same string as @src (including the terminating null character), and
+ * should not overlap in memory with @src.
+ * */
+char *
+strcpy(char *dst, const char *src) {
+#ifdef __HAVE_ARCH_STRCPY
+    return __strcpy(dst, src);
+#else
+    char *p = dst;
+    while ((*p ++ = *src ++) != '\0')
+        /* nothing */;
+    return dst;
+#endif /* __HAVE_ARCH_STRCPY */
+}
+
+/* *
+ * strncpy - copies the first @len characters of @src to @dst. If the end of string @src
+ * if found before @len characters have been copied, @dst is padded with '\0' until a
+ * total of @len characters have been written to it.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ * @len:    maximum number of characters to be copied from @src
+ *
+ * The return value is @dst
+ * */
+char *
+strncpy(char *dst, const char *src, size_t len) {
+    char *p = dst;
+    while (len > 0) {
+        if ((*p = *src) != '\0') {
+            src ++;
+        }
+        p ++, len --;
+    }
+    return dst;
+}
+
+/* *
+ * strcmp - compares the string @s1 and @s2
+ * @s1:     string to be compared
+ * @s2:     string to be compared
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ or until a terminanting null-character is reached.
+ *
+ * Returns an integral value indicating the relationship between the strings:
+ * - A zero value indicates that both strings are equal;
+ * - A value greater than zero indicates that the first character that does
+ *   not match has a greater value in @s1 than in @s2;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+strcmp(const char *s1, const char *s2) {
+#ifdef __HAVE_ARCH_STRCMP
+    return __strcmp(s1, s2);
+#else
+    while (*s1 != '\0' && *s1 == *s2) {
+        s1 ++, s2 ++;
+    }
+    return (int)((unsigned char)*s1 - (unsigned char)*s2);
+#endif /* __HAVE_ARCH_STRCMP */
+}
+
+/* *
+ * strncmp - compares up to @n characters of the string @s1 to those of the string @s2
+ * @s1:     string to be compared
+ * @s2:     string to be compared
+ * @n:      maximum number of characters to compare
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ, until a terminating null-character is reached, or
+ * until @n characters match in both strings, whichever happens first.
+ * */
+int
+strncmp(const char *s1, const char *s2, size_t n) {
+    while (n > 0 && *s1 != '\0' && *s1 == *s2) {
+        n --, s1 ++, s2 ++;
+    }
+    return (n == 0) ? 0 : (int)((unsigned char)*s1 - (unsigned char)*s2);
+}
+
+/* *
+ * strchr - locates first occurrence of character in string
+ * @s:      the input string
+ * @c:      character to be located
+ *
+ * The strchr() function returns a pointer to the first occurrence of
+ * character in @s. If the value is not found, the function returns 'NULL'.
+ * */
+char *
+strchr(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            return (char *)s;
+        }
+        s ++;
+    }
+    return NULL;
+}
+
+/* *
+ * strfind - locates first occurrence of character in string
+ * @s:      the input string
+ * @c:      character to be located
+ *
+ * The strfind() function is like strchr() except that if @c is
+ * not found in @s, then it returns a pointer to the null byte at the
+ * end of @s, rather than 'NULL'.
+ * */
+char *
+strfind(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            break;
+        }
+        s ++;
+    }
+    return (char *)s;
+}
+
+/* *
+ * strtol - converts string to long integer
+ * @s:      the input string that contains the representation of an integer number
+ * @endptr: reference to an object of type char *, whose value is set by the
+ *          function to the next character in @s after the numerical value. This
+ *          parameter can also be a null pointer, in which case it is not used.
+ * @base:   x
+ *
+ * The function first discards as many whitespace characters as necessary until
+ * the first non-whitespace character is found. Then, starting from this character,
+ * takes as many characters as possible that are valid following a syntax that
+ * depends on the base parameter, and interprets them as a numerical value. Finally,
+ * a pointer to the first character following the integer representation in @s
+ * is stored in the object pointed by @endptr.
+ *
+ * If the value of base is zero, the syntax expected is similar to that of
+ * integer constants, which is formed by a succession of:
+ * - An optional plus or minus sign;
+ * - An optional prefix indicating octal or hexadecimal base ("0" or "0x" respectively)
+ * - A sequence of decimal digits (if no base prefix was specified) or either octal
+ *   or hexadecimal digits if a specific prefix is present
+ *
+ * If the base value is between 2 and 36, the format expected for the integral number
+ * is a succession of the valid digits and/or letters needed to represent integers of
+ * the specified radix (starting from '0' and up to 'z'/'Z' for radix 36). The
+ * sequence may optionally be preceded by a plus or minus sign and, if base is 16,
+ * an optional "0x" or "0X" prefix.
+ *
+ * The strtol() function returns the converted integral number as a long int value.
+ * */
+long
+strtol(const char *s, char **endptr, int base) {
+    int neg = 0;
+    long val = 0;
+
+    // gobble initial whitespace
+    while (*s == ' ' || *s == '\t') {
+        s ++;
+    }
+
+    // plus/minus sign
+    if (*s == '+') {
+        s ++;
+    }
+    else if (*s == '-') {
+        s ++, neg = 1;
+    }
+
+    // hex or octal base prefix
+    if ((base == 0 || base == 16) && (s[0] == '0' && s[1] == 'x')) {
+        s += 2, base = 16;
+    }
+    else if (base == 0 && s[0] == '0') {
+        s ++, base = 8;
+    }
+    else if (base == 0) {
+        base = 10;
+    }
+
+    // digits
+    while (1) {
+        int dig;
+
+        if (*s >= '0' && *s <= '9') {
+            dig = *s - '0';
+        }
+        else if (*s >= 'a' && *s <= 'z') {
+            dig = *s - 'a' + 10;
+        }
+        else if (*s >= 'A' && *s <= 'Z') {
+            dig = *s - 'A' + 10;
+        }
+        else {
+            break;
+        }
+        if (dig >= base) {
+            break;
+        }
+        s ++, val = (val * base) + dig;
+        // we don't properly detect overflow!
+    }
+
+    if (endptr) {
+        *endptr = (char *) s;
+    }
+    return (neg ? -val : val);
+}
+
+/* *
+ * memset - sets the first @n bytes of the memory area pointed by @s
+ * to the specified value @c.
+ * @s:      pointer the the memory area to fill
+ * @c:      value to set
+ * @n:      number of bytes to be set to the value
+ *
+ * The memset() function returns @s.
+ * */
+void *
+memset(void *s, char c, size_t n) {
+#ifdef __HAVE_ARCH_MEMSET
+    return __memset(s, c, n);
+#else
+    char *p = s;
+    while (n -- > 0) {
+        *p ++ = c;
+    }
+    return s;
+#endif /* __HAVE_ARCH_MEMSET */
+}
+
+/* *
+ * memmove - copies the values of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst. @src and @dst are allowed to overlap.
+ * @dst     pointer to the destination array where the content is to be copied
+ * @src     pointer to the source of data to by copied
+ * @n:      number of bytes to copy
+ *
+ * The memmove() function returns @dst.
+ * */
+void *
+memmove(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMMOVE
+    return __memmove(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    if (s < d && s + n > d) {
+        s += n, d += n;
+        while (n -- > 0) {
+            *-- d = *-- s;
+        }
+    } else {
+        while (n -- > 0) {
+            *d ++ = *s ++;
+        }
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMMOVE */
+}
+
+/* *
+ * memcpy - copies the value of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst.
+ * @dst     pointer to the destination array where the content is to be copied
+ * @src     pointer to the source of data to by copied
+ * @n:      number of bytes to copy
+ *
+ * The memcpy() returns @dst.
+ *
+ * Note that, the function does not check any terminating null character in @src,
+ * it always copies exactly @n bytes. To avoid overflows, the size of arrays pointed
+ * by both @src and @dst, should be at least @n bytes, and should not overlap
+ * (for overlapping memory area, memmove is a safer approach).
+ * */
+void *
+memcpy(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMCPY
+    return __memcpy(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    while (n -- > 0) {
+        *d ++ = *s ++;
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMCPY */
+}
+
+/* *
+ * memcmp - compares two blocks of memory
+ * @v1:     pointer to block of memory
+ * @v2:     pointer to block of memory
+ * @n:      number of bytes to compare
+ *
+ * The memcmp() functions returns an integral value indicating the
+ * relationship between the content of the memory blocks:
+ * - A zero value indicates that the contents of both memory blocks are equal;
+ * - A value greater than zero indicates that the first byte that does not
+ *   match in both memory blocks has a greater value in @v1 than in @v2
+ *   as if evaluated as unsigned char values;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+memcmp(const void *v1, const void *v2, size_t n) {
+    const char *s1 = (const char *)v1;
+    const char *s2 = (const char *)v2;
+    while (n -- > 0) {
+        if (*s1 != *s2) {
+            return (int)((unsigned char)*s1 - (unsigned char)*s2);
+        }
+        s1 ++, s2 ++;
+    }
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/string.h b/related_info/lab5/lab5-spoc-discuss/libs/string.h
new file mode 100644
index 0000000..14d0aac
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/string.h
@@ -0,0 +1,25 @@
+#ifndef __LIBS_STRING_H__
+#define __LIBS_STRING_H__
+
+#include <defs.h>
+
+size_t strlen(const char *s);
+size_t strnlen(const char *s, size_t len);
+
+char *strcpy(char *dst, const char *src);
+char *strncpy(char *dst, const char *src, size_t len);
+
+int strcmp(const char *s1, const char *s2);
+int strncmp(const char *s1, const char *s2, size_t n);
+
+char *strchr(const char *s, char c);
+char *strfind(const char *s, char c);
+long strtol(const char *s, char **endptr, int base);
+
+void *memset(void *s, char c, size_t n);
+void *memmove(void *dst, const void *src, size_t n);
+void *memcpy(void *dst, const void *src, size_t n);
+int memcmp(const void *v1, const void *v2, size_t n);
+
+#endif /* !__LIBS_STRING_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/unistd.h b/related_info/lab5/lab5-spoc-discuss/libs/unistd.h
new file mode 100644
index 0000000..56ce6f5
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/unistd.h
@@ -0,0 +1,29 @@
+#ifndef __LIBS_UNISTD_H__
+#define __LIBS_UNISTD_H__
+
+#define T_SYSCALL           0x80
+
+/* syscall number */
+#define SYS_exit            1
+#define SYS_fork            2
+#define SYS_wait            3
+#define SYS_exec            4
+#define SYS_clone           5
+#define SYS_yield           10
+#define SYS_sleep           11
+#define SYS_kill            12
+#define SYS_gettime         17
+#define SYS_getpid          18
+#define SYS_brk             19
+#define SYS_mmap            20
+#define SYS_munmap          21
+#define SYS_shmem           22
+#define SYS_putc            30
+#define SYS_pgdir           31
+
+/* SYS_fork flags */
+#define CLONE_VM            0x00000100  // set if VM shared between processes
+#define CLONE_THREAD        0x00000200  // thread group
+
+#endif /* !__LIBS_UNISTD_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/libs/x86.h b/related_info/lab5/lab5-spoc-discuss/libs/x86.h
new file mode 100644
index 0000000..b29f671
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/libs/x86.h
@@ -0,0 +1,302 @@
+#ifndef __LIBS_X86_H__
+#define __LIBS_X86_H__
+
+#include <defs.h>
+
+#define do_div(n, base) ({                                          \
+            unsigned long __upper, __low, __high, __mod, __base;    \
+            __base = (base);                                        \
+            asm ("" : "=a" (__low), "=d" (__high) : "A" (n));       \
+            __upper = __high;                                       \
+            if (__high != 0) {                                      \
+                __upper = __high % __base;                          \
+                __high = __high / __base;                           \
+            }                                                       \
+            asm ("divl %2" : "=a" (__low), "=d" (__mod)             \
+                : "rm" (__base), "0" (__low), "1" (__upper));       \
+            asm ("" : "=A" (n) : "a" (__low), "d" (__high));        \
+            __mod;                                                  \
+        })
+
+#define barrier() __asm__ __volatile__ ("" ::: "memory")
+
+static inline uint8_t inb(uint16_t port) __attribute__((always_inline));
+static inline void insl(uint32_t port, void *addr, int cnt) __attribute__((always_inline));
+static inline void outb(uint16_t port, uint8_t data) __attribute__((always_inline));
+static inline void outw(uint16_t port, uint16_t data) __attribute__((always_inline));
+static inline void outsl(uint32_t port, const void *addr, int cnt) __attribute__((always_inline));
+static inline uint32_t read_ebp(void) __attribute__((always_inline));
+static inline void breakpoint(void) __attribute__((always_inline));
+static inline uint32_t read_dr(unsigned regnum) __attribute__((always_inline));
+static inline void write_dr(unsigned regnum, uint32_t value) __attribute__((always_inline));
+
+/* Pseudo-descriptors used for LGDT, LLDT(not used) and LIDT instructions. */
+struct pseudodesc {
+    uint16_t pd_lim;        // Limit
+    uintptr_t pd_base;      // Base address
+} __attribute__ ((packed));
+
+static inline void lidt(struct pseudodesc *pd) __attribute__((always_inline));
+static inline void sti(void) __attribute__((always_inline));
+static inline void cli(void) __attribute__((always_inline));
+static inline void ltr(uint16_t sel) __attribute__((always_inline));
+static inline uint32_t read_eflags(void) __attribute__((always_inline));
+static inline void write_eflags(uint32_t eflags) __attribute__((always_inline));
+static inline void lcr0(uintptr_t cr0) __attribute__((always_inline));
+static inline void lcr3(uintptr_t cr3) __attribute__((always_inline));
+static inline uintptr_t rcr0(void) __attribute__((always_inline));
+static inline uintptr_t rcr1(void) __attribute__((always_inline));
+static inline uintptr_t rcr2(void) __attribute__((always_inline));
+static inline uintptr_t rcr3(void) __attribute__((always_inline));
+static inline void invlpg(void *addr) __attribute__((always_inline));
+
+static inline uint8_t
+inb(uint16_t port) {
+    uint8_t data;
+    asm volatile ("inb %1, %0" : "=a" (data) : "d" (port) : "memory");
+    return data;
+}
+
+static inline void
+insl(uint32_t port, void *addr, int cnt) {
+    asm volatile (
+        "cld;"
+        "repne; insl;"
+        : "=D" (addr), "=c" (cnt)
+        : "d" (port), "0" (addr), "1" (cnt)
+        : "memory", "cc");
+}
+
+static inline void
+outb(uint16_t port, uint8_t data) {
+    asm volatile ("outb %0, %1" :: "a" (data), "d" (port) : "memory");
+}
+
+static inline void
+outw(uint16_t port, uint16_t data) {
+    asm volatile ("outw %0, %1" :: "a" (data), "d" (port) : "memory");
+}
+
+static inline void
+outsl(uint32_t port, const void *addr, int cnt) {
+    asm volatile (
+        "cld;"
+        "repne; outsl;"
+        : "=S" (addr), "=c" (cnt)
+        : "d" (port), "0" (addr), "1" (cnt)
+        : "memory", "cc");
+}
+
+static inline uint32_t
+read_ebp(void) {
+    uint32_t ebp;
+    asm volatile ("movl %%ebp, %0" : "=r" (ebp));
+    return ebp;
+}
+
+static inline void
+breakpoint(void) {
+    asm volatile ("int $3");
+}
+
+static inline uint32_t
+read_dr(unsigned regnum) {
+    uint32_t value = 0;
+    switch (regnum) {
+    case 0: asm volatile ("movl %%db0, %0" : "=r" (value)); break;
+    case 1: asm volatile ("movl %%db1, %0" : "=r" (value)); break;
+    case 2: asm volatile ("movl %%db2, %0" : "=r" (value)); break;
+    case 3: asm volatile ("movl %%db3, %0" : "=r" (value)); break;
+    case 6: asm volatile ("movl %%db6, %0" : "=r" (value)); break;
+    case 7: asm volatile ("movl %%db7, %0" : "=r" (value)); break;
+    }
+    return value;
+}
+
+static void
+write_dr(unsigned regnum, uint32_t value) {
+    switch (regnum) {
+    case 0: asm volatile ("movl %0, %%db0" :: "r" (value)); break;
+    case 1: asm volatile ("movl %0, %%db1" :: "r" (value)); break;
+    case 2: asm volatile ("movl %0, %%db2" :: "r" (value)); break;
+    case 3: asm volatile ("movl %0, %%db3" :: "r" (value)); break;
+    case 6: asm volatile ("movl %0, %%db6" :: "r" (value)); break;
+    case 7: asm volatile ("movl %0, %%db7" :: "r" (value)); break;
+    }
+}
+
+static inline void
+lidt(struct pseudodesc *pd) {
+    asm volatile ("lidt (%0)" :: "r" (pd) : "memory");
+}
+
+static inline void
+sti(void) {
+    asm volatile ("sti");
+}
+
+static inline void
+cli(void) {
+    asm volatile ("cli" ::: "memory");
+}
+
+static inline void
+ltr(uint16_t sel) {
+    asm volatile ("ltr %0" :: "r" (sel) : "memory");
+}
+
+static inline uint32_t
+read_eflags(void) {
+    uint32_t eflags;
+    asm volatile ("pushfl; popl %0" : "=r" (eflags));
+    return eflags;
+}
+
+static inline void
+write_eflags(uint32_t eflags) {
+    asm volatile ("pushl %0; popfl" :: "r" (eflags));
+}
+
+static inline void
+lcr0(uintptr_t cr0) {
+    asm volatile ("mov %0, %%cr0" :: "r" (cr0) : "memory");
+}
+
+static inline void
+lcr3(uintptr_t cr3) {
+    asm volatile ("mov %0, %%cr3" :: "r" (cr3) : "memory");
+}
+
+static inline uintptr_t
+rcr0(void) {
+    uintptr_t cr0;
+    asm volatile ("mov %%cr0, %0" : "=r" (cr0) :: "memory");
+    return cr0;
+}
+
+static inline uintptr_t
+rcr1(void) {
+    uintptr_t cr1;
+    asm volatile ("mov %%cr1, %0" : "=r" (cr1) :: "memory");
+    return cr1;
+}
+
+static inline uintptr_t
+rcr2(void) {
+    uintptr_t cr2;
+    asm volatile ("mov %%cr2, %0" : "=r" (cr2) :: "memory");
+    return cr2;
+}
+
+static inline uintptr_t
+rcr3(void) {
+    uintptr_t cr3;
+    asm volatile ("mov %%cr3, %0" : "=r" (cr3) :: "memory");
+    return cr3;
+}
+
+static inline void
+invlpg(void *addr) {
+    asm volatile ("invlpg (%0)" :: "r" (addr) : "memory");
+}
+
+static inline int __strcmp(const char *s1, const char *s2) __attribute__((always_inline));
+static inline char *__strcpy(char *dst, const char *src) __attribute__((always_inline));
+static inline void *__memset(void *s, char c, size_t n) __attribute__((always_inline));
+static inline void *__memmove(void *dst, const void *src, size_t n) __attribute__((always_inline));
+static inline void *__memcpy(void *dst, const void *src, size_t n) __attribute__((always_inline));
+
+#ifndef __HAVE_ARCH_STRCMP
+#define __HAVE_ARCH_STRCMP
+static inline int
+__strcmp(const char *s1, const char *s2) {
+    int d0, d1, ret;
+    asm volatile (
+        "1: lodsb;"
+        "scasb;"
+        "jne 2f;"
+        "testb %%al, %%al;"
+        "jne 1b;"
+        "xorl %%eax, %%eax;"
+        "jmp 3f;"
+        "2: sbbl %%eax, %%eax;"
+        "orb $1, %%al;"
+        "3:"
+        : "=a" (ret), "=&S" (d0), "=&D" (d1)
+        : "1" (s1), "2" (s2)
+        : "memory");
+    return ret;
+}
+
+#endif /* __HAVE_ARCH_STRCMP */
+
+#ifndef __HAVE_ARCH_STRCPY
+#define __HAVE_ARCH_STRCPY
+static inline char *
+__strcpy(char *dst, const char *src) {
+    int d0, d1, d2;
+    asm volatile (
+        "1: lodsb;"
+        "stosb;"
+        "testb %%al, %%al;"
+        "jne 1b;"
+        : "=&S" (d0), "=&D" (d1), "=&a" (d2)
+        : "0" (src), "1" (dst) : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_STRCPY */
+
+#ifndef __HAVE_ARCH_MEMSET
+#define __HAVE_ARCH_MEMSET
+static inline void *
+__memset(void *s, char c, size_t n) {
+    int d0, d1;
+    asm volatile (
+        "rep; stosb;"
+        : "=&c" (d0), "=&D" (d1)
+        : "0" (n), "a" (c), "1" (s)
+        : "memory");
+    return s;
+}
+#endif /* __HAVE_ARCH_MEMSET */
+
+#ifndef __HAVE_ARCH_MEMMOVE
+#define __HAVE_ARCH_MEMMOVE
+static inline void *
+__memmove(void *dst, const void *src, size_t n) {
+    if (dst < src) {
+        return __memcpy(dst, src, n);
+    }
+    int d0, d1, d2;
+    asm volatile (
+        "std;"
+        "rep; movsb;"
+        "cld;"
+        : "=&c" (d0), "=&S" (d1), "=&D" (d2)
+        : "0" (n), "1" (n - 1 + src), "2" (n - 1 + dst)
+        : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMMOVE */
+
+#ifndef __HAVE_ARCH_MEMCPY
+#define __HAVE_ARCH_MEMCPY
+static inline void *
+__memcpy(void *dst, const void *src, size_t n) {
+    int d0, d1, d2;
+    asm volatile (
+        "rep; movsl;"
+        "movl %4, %%ecx;"
+        "andl $3, %%ecx;"
+        "jz 1f;"
+        "rep; movsb;"
+        "1:"
+        : "=&c" (d0), "=&D" (d1), "=&S" (d2)
+        : "0" (n / 4), "g" (n), "1" (dst), "2" (src)
+        : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMCPY */
+
+#endif /* !__LIBS_X86_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/boot.ld b/related_info/lab5/lab5-spoc-discuss/tools/boot.ld
new file mode 100644
index 0000000..dc732b0
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/boot.ld
@@ -0,0 +1,15 @@
+OUTPUT_FORMAT("elf32-i386")
+OUTPUT_ARCH(i386)
+
+SECTIONS {
+    . = 0x7C00;
+
+    .startup : {
+        *bootasm.o(.text)
+    }
+
+    .text : { *(.text) }
+    .data : { *(.data .rodata) }
+    
+    /DISCARD/ : { *(.eh_*) }
+}
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/function.mk b/related_info/lab5/lab5-spoc-discuss/tools/function.mk
new file mode 100644
index 0000000..9b8be0c
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/function.mk
@@ -0,0 +1,95 @@
+OBJPREFIX	:= __objs_
+
+.SECONDEXPANSION:
+# -------------------- function begin --------------------
+
+# list all files in some directories: (#directories, #types)
+listf = $(filter $(if $(2),$(addprefix %.,$(2)),%),\
+		  $(wildcard $(addsuffix $(SLASH)*,$(1))))
+
+# get .o obj files: (#files[, packet])
+toobj = $(addprefix $(OBJDIR)$(SLASH)$(if $(2),$(2)$(SLASH)),\
+		$(addsuffix .o,$(basename $(1))))
+
+# get .d dependency files: (#files[, packet])
+todep = $(patsubst %.o,%.d,$(call toobj,$(1),$(2)))
+
+totarget = $(addprefix $(BINDIR)$(SLASH),$(1))
+
+# change $(name) to $(OBJPREFIX)$(name): (#names)
+packetname = $(if $(1),$(addprefix $(OBJPREFIX),$(1)),$(OBJPREFIX))
+
+# cc compile template, generate rule for dep, obj: (file, cc[, flags, dir])
+define cc_template
+$$(call todep,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@$(2) -I$$(dir $(1)) $(3) -MM $$< -MT "$$(patsubst %.d,%.o,$$@) $$@"> $$@
+$$(call toobj,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@echo + cc $$<
+	$(V)$(2) -I$$(dir $(1)) $(3) -c $$< -o $$@
+ALLOBJS += $$(call toobj,$(1),$(4))
+endef
+
+# compile file: (#files, cc[, flags, dir])
+define do_cc_compile
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(4))))
+endef
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+define do_add_files_to_packet
+__temp_packet__ := $(call packetname,$(4))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+__temp_objs__ := $(call toobj,$(1),$(5))
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(5))))
+$$(__temp_packet__) += $$(__temp_objs__)
+endef
+
+# add objs to packet: (#objs, packet)
+define do_add_objs_to_packet
+__temp_packet__ := $(call packetname,$(2))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+$$(__temp_packet__) += $(1)
+endef
+
+# add packets and objs to target (target, #packes, #objs[, cc, flags])
+define do_create_target
+__temp_target__ = $(call totarget,$(1))
+__temp_objs__ = $$(foreach p,$(call packetname,$(2)),$$($$(p))) $(3)
+TARGETS += $$(__temp_target__)
+ifneq ($(4),)
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+	$(V)$(4) $(5) $$^ -o $$@
+else
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+endif
+endef
+
+# finish all
+define do_finish_all
+ALLDEPS = $$(ALLOBJS:.o=.d)
+$$(sort $$(dir $$(ALLOBJS)) $(BINDIR)$(SLASH) $(OBJDIR)$(SLASH)):
+	@$(MKDIR) $$@
+endef
+
+# --------------------  function end  --------------------
+# compile file: (#files, cc[, flags, dir])
+cc_compile = $(eval $(call do_cc_compile,$(1),$(2),$(3),$(4)))
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+add_files = $(eval $(call do_add_files_to_packet,$(1),$(2),$(3),$(4),$(5)))
+
+# add objs to packet: (#objs, packet)
+add_objs = $(eval $(call do_add_objs_to_packet,$(1),$(2)))
+
+# add packets and objs to target (target, #packes, #objs, cc, [, flags])
+create_target = $(eval $(call do_create_target,$(1),$(2),$(3),$(4),$(5)))
+
+read_packet = $(foreach p,$(call packetname,$(1)),$($(p)))
+
+add_dependency = $(eval $(1): $(2))
+
+finish_all = $(eval $(call do_finish_all))
+
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/gdbinit b/related_info/lab5/lab5-spoc-discuss/tools/gdbinit
new file mode 100644
index 0000000..df5df85
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/gdbinit
@@ -0,0 +1,3 @@
+file bin/kernel
+target remote :1234
+break kern_init
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/grade.sh b/related_info/lab5/lab5-spoc-discuss/tools/grade.sh
new file mode 100644
index 0000000..8250993
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/grade.sh
@@ -0,0 +1,556 @@
+#!/bin/sh
+
+verbose=false
+if [ "x$1" = "x-v" ]; then
+    verbose=true
+    out=/dev/stdout
+    err=/dev/stderr
+else
+    out=/dev/null
+    err=/dev/null
+fi
+
+## make & makeopts
+if gmake --version > /dev/null 2>&1; then
+    make=gmake;
+else
+    make=make;
+fi
+
+makeopts="--quiet --no-print-directory -j"
+
+make_print() {
+    echo `$make $makeopts print-$1`
+}
+
+## command tools
+awk='awk'
+bc='bc'
+date='date'
+grep='grep'
+rm='rm -f'
+sed='sed'
+
+## symbol table
+sym_table='obj/kernel.sym'
+
+## gdb & gdbopts
+gdb="$(make_print GDB)"
+gdbport='1234'
+
+gdb_in="$(make_print GRADE_GDB_IN)"
+
+## qemu & qemuopts
+qemu="$(make_print qemu)"
+
+qemu_out="$(make_print GRADE_QEMU_OUT)"
+
+if $qemu -nographic -help | grep -q '^-gdb'; then
+    qemugdb="-gdb tcp::$gdbport"
+else
+    qemugdb="-s -p $gdbport"
+fi
+
+## default variables
+default_timeout=30
+default_pts=5
+
+pts=5
+part=0
+part_pos=0
+total=0
+total_pos=0
+
+## default functions
+update_score() {
+    total=`expr $total + $part`
+    total_pos=`expr $total_pos + $part_pos`
+    part=0
+    part_pos=0
+}
+
+get_time() {
+    echo `$date +%s.%N 2> /dev/null`
+}
+
+show_part() {
+    echo "Part $1 Score: $part/$part_pos"
+    echo
+    update_score
+}
+
+show_final() {
+    update_score
+    echo "Total Score: $total/$total_pos"
+    if [ $total -lt $total_pos ]; then
+        exit 1
+    fi
+}
+
+show_time() {
+    t1=$(get_time)
+    time=`echo "scale=1; ($t1-$t0)/1" | $sed 's/.N/.0/g' | $bc 2> /dev/null`
+    echo "(${time}s)"
+}
+
+show_build_tag() {
+    echo "$1:" | $awk '{printf "%-24s ", $0}'
+}
+
+show_check_tag() {
+    echo "$1:" | $awk '{printf "  -%-40s  ", $0}'
+}
+
+show_msg() {
+    echo $1
+    shift
+    if [ $# -gt 0 ]; then
+        echo "$@" | awk '{printf "   %s\n", $0}'
+        echo
+    fi
+}
+
+pass() {
+    show_msg OK "$@"
+    part=`expr $part + $pts`
+    part_pos=`expr $part_pos + $pts`
+}
+
+fail() {
+    show_msg WRONG "$@"
+    part_pos=`expr $part_pos + $pts`
+}
+
+run_qemu() {
+    # Run qemu with serial output redirected to $qemu_out. If $brkfun is non-empty,
+    # wait until $brkfun is reached or $timeout expires, then kill QEMU
+    qemuextra=
+    if [ "$brkfun" ]; then
+        qemuextra="-S $qemugdb"
+    fi
+
+    if [ -z "$timeout" ] || [ $timeout -le 0 ]; then
+        timeout=$default_timeout;
+    fi
+
+    t0=$(get_time)
+    (
+        ulimit -t $timeout
+        exec $qemu -nographic $qemuopts -serial file:$qemu_out -monitor null -no-reboot $qemuextra
+    ) > $out 2> $err &
+    pid=$!
+
+    # wait for QEMU to start
+    sleep 1
+
+    if [ -n "$brkfun" ]; then
+        # find the address of the kernel $brkfun function
+        brkaddr=`$grep " $brkfun\$" $sym_table | $sed -e's/ .*$//g'`
+        (
+            echo "target remote localhost:$gdbport"
+            echo "break *0x$brkaddr"
+            echo "continue"
+        ) > $gdb_in
+
+        $gdb -batch -nx -x $gdb_in > /dev/null 2>&1
+
+        # make sure that QEMU is dead
+        # on OS X, exiting gdb doesn't always exit qemu
+        kill $pid > /dev/null 2>&1
+    fi
+}
+
+build_run() {
+    # usage: build_run <tag> <args>
+    show_build_tag "$1"
+    shift
+
+    if $verbose; then
+        echo "$make $@ ..."
+    fi
+    $make $makeopts $@ 'DEFS+=-DDEBUG_GRADE' > $out 2> $err
+
+    if [ $? -ne 0 ]; then
+        echo $make $@ failed
+        exit 1
+    fi
+
+    # now run qemu and save the output
+    run_qemu
+
+    show_time
+}
+
+check_result() {
+    # usage: check_result <tag> <check> <check args...>
+    show_check_tag "$1"
+    shift
+
+    # give qemu some time to run (for asynchronous mode)
+    if [ ! -s $qemu_out ]; then
+        sleep 4
+    fi
+
+    if [ ! -s $qemu_out ]; then
+        fail > /dev/null
+        echo 'no $qemu_out'
+    else
+        check=$1
+        shift
+        $check "$@"
+    fi
+}
+
+check_regexps() {
+    okay=yes
+    not=0
+    reg=0
+    error=
+    for i do
+        if [ "x$i" = "x!" ]; then
+            not=1
+        elif [ "x$i" = "x-" ]; then
+            reg=1
+        else
+            if [ $reg -ne 0 ]; then
+                $grep '-E' "^$i\$" $qemu_out > /dev/null
+            else
+                $grep '-F' "$i" $qemu_out > /dev/null
+            fi
+            found=$(($? == 0))
+            if [ $found -eq $not ]; then
+                if [ $found -eq 0 ]; then
+                    msg="!! error: missing '$i'"
+                else
+                    msg="!! error: got unexpected line '$i'"
+                fi
+                okay=no
+                if [ -z "$error" ]; then
+                    error="$msg"
+                else
+                    error="$error\n$msg"
+                fi
+            fi
+            not=0
+            reg=0
+        fi
+    done
+    if [ "$okay" = "yes" ]; then
+        pass
+    else
+        fail "$error"
+        if $verbose; then
+            exit 1
+        fi
+    fi
+}
+
+run_test() {
+    # usage: run_test [-tag <tag>] [-prog <prog>] [-Ddef...] [-check <check>] checkargs ...
+    tag=
+    prog=
+    check=check_regexps
+    while true; do
+        select=
+        case $1 in
+            -tag|-prog)
+                select=`expr substr $1 2 ${#1}`
+                eval $select='$2'
+                ;;
+        esac
+        if [ -z "$select" ]; then
+            break
+        fi
+        shift
+        shift
+    done
+    defs=
+    while expr "x$1" : "x-D.*" > /dev/null; do
+        defs="DEFS+='$1' $defs"
+        shift
+    done
+    if [ "x$1" = "x-check" ]; then
+        check=$2
+        shift
+        shift
+    fi
+
+    if [ -z "$prog" ]; then
+        $make $makeopts touch > /dev/null 2>&1
+        args="$defs"
+    else
+        if [ -z "$tag" ]; then
+            tag="$prog"
+        fi
+        args="build-$prog $defs"
+    fi
+
+    build_run "$tag" "$args"
+
+    check_result 'check result' "$check" "$@"
+}
+
+quick_run() {
+    # usage: quick_run <tag> [-Ddef...]
+    tag="$1"
+    shift
+    defs=
+    while expr "x$1" : "x-D.*" > /dev/null; do
+        defs="DEFS+='$1' $defs"
+        shift
+    done
+
+    $make $makeopts touch > /dev/null 2>&1
+    build_run "$tag" "$defs"
+}
+
+quick_check() {
+    # usage: quick_check <tag> checkargs ...
+    tag="$1"
+    shift
+    check_result "$tag" check_regexps "$@"
+}
+
+## kernel image
+osimg=$(make_print ucoreimg)
+
+## swap image
+swapimg=$(make_print swapimg)
+
+## set default qemu-options
+qemuopts="-hda $osimg -drive file=$swapimg,media=disk,cache=writeback"
+
+## set break-function, default is readline
+brkfun=readline
+
+default_check() {
+    pts=7
+    check_regexps "$@"
+
+    pts=3
+    quick_check 'check output'                                  \
+    'memory management: default_pmm_manager'                      \
+    'check_alloc_page() succeeded!'                             \
+    'check_pgdir() succeeded!'                                  \
+    'check_boot_pgdir() succeeded!'				\
+    'PDE(0e0) c0000000-f8000000 38000000 urw'                   \
+    '  |-- PTE(38000) c0000000-f8000000 38000000 -rw'           \
+    'PDE(001) fac00000-fb000000 00400000 -rw'                   \
+    '  |-- PTE(000e0) faf00000-fafe0000 000e0000 urw'           \
+    '  |-- PTE(00001) fafeb000-fafec000 00001000 -rw'		\
+    'check_slab() succeeded!'					\
+    'check_vma_struct() succeeded!'                             \
+    'page fault at 0x00000100: K/W [no page found].'            \
+    'check_pgfault() succeeded!'                                \
+    'check_vmm() succeeded.'					\
+    'page fault at 0x00001000: K/W [no page found].'            \
+    'page fault at 0x00002000: K/W [no page found].'            \
+    'page fault at 0x00003000: K/W [no page found].'            \
+    'page fault at 0x00004000: K/W [no page found].'            \
+    'write Virt Page e in fifo_check_swap'			\
+    'page fault at 0x00005000: K/W [no page found].'		\
+    'page fault at 0x00001000: K/W [no page found]'		\
+    'page fault at 0x00002000: K/W [no page found].'		\
+    'page fault at 0x00003000: K/W [no page found].'		\
+    'page fault at 0x00004000: K/W [no page found].'		\
+    'check_swap() succeeded!'					\
+    '++ setup timer interrupts'
+}
+
+## check now!!
+
+run_test -prog 'badsegment' -check default_check                \
+        'kernel_execve: pid = 2, name = "badsegment".'          \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x0000000d General Protection'                    \
+        '  err  0x00000028'                                     \
+      - '  eip  0x008.....'                                     \
+      - '  esp  0xaff.....'                                     \
+        '  cs   0x----001b'                                     \
+        '  ss   0x----0023'                                     \
+    ! - 'user panic at .*'
+
+run_test -prog 'divzero' -check default_check                   \
+        'kernel_execve: pid = 2, name = "divzero".'             \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x00000000 Divide error'                          \
+      - '  eip  0x008.....'                                     \
+      - '  esp  0xaff.....'                                     \
+        '  cs   0x----001b'                                     \
+        '  ss   0x----0023'                                     \
+    ! - 'user panic at .*'
+
+run_test -prog 'softint' -check default_check                   \
+        'kernel_execve: pid = 2, name = "softint".'             \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x0000000d General Protection'                    \
+        '  err  0x00000072'                                     \
+      - '  eip  0x008.....'                                     \
+      - '  esp  0xaff.....'                                     \
+        '  cs   0x----001b'                                     \
+        '  ss   0x----0023'                                     \
+    ! - 'user panic at .*'
+
+pts=10
+
+run_test -prog 'faultread'  -check default_check                                     \
+        'kernel_execve: pid = 2, name = "faultread".'           \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x0000000e Page Fault'                            \
+        '  err  0x00000004'                                     \
+      - '  eip  0x008.....'                                     \
+    ! - 'user panic at .*'
+
+run_test -prog 'faultreadkernel' -check default_check                                \
+        'kernel_execve: pid = 2, name = "faultreadkernel".'     \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x0000000e Page Fault'                            \
+        '  err  0x00000005'                                     \
+      - '  eip  0x008.....'                                     \
+    ! - 'user panic at .*'
+
+run_test -prog 'hello' -check default_check                                          \
+        'kernel_execve: pid = 2, name = "hello".'               \
+        'Hello world!!.'                                        \
+        'I am process 2.'                                       \
+        'hello pass.'
+
+run_test -prog 'testbss' -check default_check                                        \
+        'kernel_execve: pid = 2, name = "testbss".'             \
+        'Making sure bss works right...'                        \
+        'Yes, good.  Now doing a wild write off the end...'     \
+        'testbss may pass.'                                     \
+      - 'trapframe at 0xc.......'                               \
+        'trap 0x0000000e Page Fault'                            \
+        '  err  0x00000006'                                     \
+      - '  eip  0x008.....'                                     \
+        'killed by kernel.'                                     \
+    ! - 'user panic at .*'
+
+run_test -prog 'pgdir' -check default_check                                          \
+        'kernel_execve: pid = 2, name = "pgdir".'               \
+        'I am 2, print pgdir.'                                  \
+        'PDE(001) 00800000-00c00000 00400000 urw'               \
+        '  |-- PTE(00002) 00800000-00802000 00002000 ur-'       \
+        '  |-- PTE(00001) 00802000-00803000 00001000 urw'       \
+        'PDE(001) afc00000-b0000000 00400000 urw'               \
+        '  |-- PTE(00004) afffc000-b0000000 00004000 urw'       \
+        'PDE(0e0) c0000000-f8000000 38000000 urw'               \
+        '  |-- PTE(38000) c0000000-f8000000 38000000 -rw'       \
+        'pgdir pass.'
+
+run_test -prog 'yield' -check default_check                                          \
+        'kernel_execve: pid = 2, name = "yield".'               \
+        'Hello, I am process 2.'                                \
+        'Back in process 2, iteration 0.'                       \
+        'Back in process 2, iteration 1.'                       \
+        'Back in process 2, iteration 2.'                       \
+        'Back in process 2, iteration 3.'                       \
+        'Back in process 2, iteration 4.'                       \
+        'All done in process 2.'                                \
+        'yield pass.'
+
+
+run_test -prog 'badarg' -check default_check                    \
+        'kernel_execve: pid = 2, name = "badarg".'              \
+        'fork ok.'                                              \
+        'badarg pass.'                                          \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'                               \
+    ! - 'user panic at .*'
+
+pts=10
+
+run_test -prog 'exit'  -check default_check                                          \
+        'kernel_execve: pid = 2, name = "exit".'                \
+        'I am the parent. Forking the child...'                 \
+        'I am the parent, waiting now..'                        \
+        'I am the child.'                                       \
+      - 'waitpid [0-9]+ ok\.'                                   \
+        'exit pass.'                                            \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'                               \
+    ! - 'user panic at .*'
+
+run_test -prog 'spin'  -check default_check                                          \
+        'kernel_execve: pid = 2, name = "spin".'                \
+        'I am the parent. Forking the child...'                 \
+        'I am the parent. Running the child...'                 \
+        'I am the child. spinning ...'                          \
+        'I am the parent.  Killing the child...'                \
+        'kill returns 0'                                        \
+        'wait returns 0'                                        \
+        'spin may pass.'                                        \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'                               \
+    ! - 'user panic at .*'
+
+run_test -prog 'waitkill'  -check default_check                                      \
+        'kernel_execve: pid = 2, name = "waitkill".'            \
+        'wait child 1.'                                         \
+        'child 2.'                                              \
+        'child 1.'                                              \
+        'kill parent ok.'                                       \
+        'kill child1 ok.'                                       \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'                               \
+    ! - 'user panic at .*'
+
+pts=15
+
+run_test -prog 'forktest'   -check default_check                                     \
+        'kernel_execve: pid = 2, name = "forktest".'            \
+        'I am child 31'                                         \
+        'I am child 19'                                         \
+        'I am child 13'                                         \
+        'I am child 0'                                          \
+        'forktest pass.'                                        \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'                               \
+    ! - 'fork claimed to work [0-9]+ times!'                    \
+    !   'wait stopped early'                                    \
+    !   'wait got too many'                                     \
+    ! - 'user panic at .*'
+
+pts=10
+run_test -prog 'forktree'    -check default_check               \
+        'kernel_execve: pid = 2, name = "forktree".'            \
+      - '....: I am '\'''\'                                     \
+      - '....: I am '\''0'\'                                    \
+      - '....: I am '\'''\'                                     \
+      - '....: I am '\''1'\'                                    \
+      - '....: I am '\''0'\'                                    \
+      - '....: I am '\''01'\'                                   \
+      - '....: I am '\''00'\'                                   \
+      - '....: I am '\''11'\'                                   \
+      - '....: I am '\''10'\'                                   \
+      - '....: I am '\''101'\'                                  \
+      - '....: I am '\''100'\'                                  \
+      - '....: I am '\''111'\'                                  \
+      - '....: I am '\''110'\'                                  \
+      - '....: I am '\''001'\'                                  \
+      - '....: I am '\''000'\'                                  \
+      - '....: I am '\''011'\'                                  \
+      - '....: I am '\''010'\'                                  \
+      - '....: I am '\''0101'\'                                 \
+      - '....: I am '\''0100'\'                                 \
+      - '....: I am '\''0111'\'                                 \
+      - '....: I am '\''0110'\'                                 \
+      - '....: I am '\''0001'\'                                 \
+      - '....: I am '\''0000'\'                                 \
+      - '....: I am '\''0011'\'                                 \
+      - '....: I am '\''0010'\'                                 \
+      - '....: I am '\''1101'\'                                 \
+      - '....: I am '\''1100'\'                                 \
+      - '....: I am '\''1111'\'                                 \
+      - '....: I am '\''1110'\'                                 \
+      - '....: I am '\''1001'\'                                 \
+      - '....: I am '\''1000'\'                                 \
+      - '....: I am '\''1011'\'                                 \
+      - '....: I am '\''1010'\'                                 \
+        'all user-mode processes have quit.'                    \
+        'init check memory pass.'
+
+## print final-score
+show_final
+
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/kernel.ld b/related_info/lab5/lab5-spoc-discuss/tools/kernel.ld
new file mode 100644
index 0000000..1838500
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/kernel.ld
@@ -0,0 +1,58 @@
+/* Simple linker script for the ucore kernel.
+   See the GNU ld 'info' manual ("info ld") to learn the syntax. */
+
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(kern_entry)
+
+SECTIONS {
+    /* Load the kernel at this address: "." means the current address */
+    . = 0xC0100000;
+
+    .text : {
+        *(.text .stub .text.* .gnu.linkonce.t.*)
+    }
+
+    PROVIDE(etext = .); /* Define the 'etext' symbol to this value */
+
+    .rodata : {
+        *(.rodata .rodata.* .gnu.linkonce.r.*)
+    }
+
+    /* Include debugging information in kernel memory */
+    .stab : {
+        PROVIDE(__STAB_BEGIN__ = .);
+        *(.stab);
+        PROVIDE(__STAB_END__ = .);
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    .stabstr : {
+        PROVIDE(__STABSTR_BEGIN__ = .);
+        *(.stabstr);
+        PROVIDE(__STABSTR_END__ = .);
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    /* Adjust the address for the data segment to the next page */
+    . = ALIGN(0x1000);
+
+    /* The data segment */
+    .data : {
+        *(.data)
+    }
+
+    PROVIDE(edata = .);
+
+    .bss : {
+        *(.bss)
+    }
+
+    PROVIDE(end = .);
+
+    /DISCARD/ : {
+        *(.eh_frame .note.GNU-stack)
+    }
+}
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/sign.c b/related_info/lab5/lab5-spoc-discuss/tools/sign.c
new file mode 100644
index 0000000..9d81bb6
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/sign.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+
+int
+main(int argc, char *argv[]) {
+    struct stat st;
+    if (argc != 3) {
+        fprintf(stderr, "Usage: <input filename> <output filename>\n");
+        return -1;
+    }
+    if (stat(argv[1], &st) != 0) {
+        fprintf(stderr, "Error opening file '%s': %s\n", argv[1], strerror(errno));
+        return -1;
+    }
+    printf("'%s' size: %lld bytes\n", argv[1], (long long)st.st_size);
+    if (st.st_size > 510) {
+        fprintf(stderr, "%lld >> 510!!\n", (long long)st.st_size);
+        return -1;
+    }
+    char buf[512];
+    memset(buf, 0, sizeof(buf));
+    FILE *ifp = fopen(argv[1], "rb");
+    int size = fread(buf, 1, st.st_size, ifp);
+    if (size != st.st_size) {
+        fprintf(stderr, "read '%s' error, size is %d.\n", argv[1], size);
+        return -1;
+    }
+    fclose(ifp);
+    buf[510] = 0x55;
+    buf[511] = 0xAA;
+    FILE *ofp = fopen(argv[2], "wb+");
+    size = fwrite(buf, 1, 512, ofp);
+    if (size != 512) {
+        fprintf(stderr, "write '%s' error, size is %d.\n", argv[2], size);
+        return -1;
+    }
+    fclose(ofp);
+    printf("build 512 bytes boot sector: '%s' success!\n", argv[2]);
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/user.ld b/related_info/lab5/lab5-spoc-discuss/tools/user.ld
new file mode 100644
index 0000000..c73b6fa
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/user.ld
@@ -0,0 +1,71 @@
+/* Simple linker script for ucore user-level programs.
+   See the GNU ld 'info' manual ("info ld") to learn the syntax. */
+
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(_start)
+
+SECTIONS {
+    /* Load programs at this address: "." means the current address */
+    . = 0x800020;
+
+    .text : {
+        *(.text .stub .text.* .gnu.linkonce.t.*)
+    }
+
+    PROVIDE(etext = .); /* Define the 'etext' symbol to this value */
+
+    .rodata : {
+        *(.rodata .rodata.* .gnu.linkonce.r.*)
+    }
+
+    /* Adjust the address for the data segment to the next page */
+    . = ALIGN(0x1000);
+
+    .data : {
+        *(.data)
+    }
+
+    PROVIDE(edata = .);
+
+    .bss : {
+        *(.bss)
+    }
+
+    PROVIDE(end = .);
+
+
+    /* Place debugging symbols so that they can be found by
+     * the kernel debugger.
+     * Specifically, the four words at 0x200000 mark the beginning of
+     * the stabs, the end of the stabs, the beginning of the stabs
+     * string table, and the end of the stabs string table, respectively.
+     */
+
+    .stab_info 0x200000 : {
+        LONG(__STAB_BEGIN__);
+        LONG(__STAB_END__);
+        LONG(__STABSTR_BEGIN__);
+        LONG(__STABSTR_END__);
+    }
+
+    .stab : {
+        __STAB_BEGIN__ = DEFINED(__STAB_BEGIN__) ? __STAB_BEGIN__ : .;
+        *(.stab);
+        __STAB_END__ = DEFINED(__STAB_END__) ? __STAB_END__ : .;
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    .stabstr : {
+        __STABSTR_BEGIN__ = DEFINED(__STABSTR_BEGIN__) ? __STABSTR_BEGIN__ : .;
+        *(.stabstr);
+        __STABSTR_END__ = DEFINED(__STABSTR_END__) ? __STABSTR_END__ : .;
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    /DISCARD/ : {
+        *(.eh_frame .note.GNU-stack .comment)
+    }
+}
diff --git a/related_info/lab5/lab5-spoc-discuss/tools/vector.c b/related_info/lab5/lab5-spoc-discuss/tools/vector.c
new file mode 100644
index 0000000..e24d77e
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/tools/vector.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+int
+main(void) {
+    printf("# handler\n");
+    printf(".text\n");
+    printf(".globl __alltraps\n");
+
+    int i;
+    for (i = 0; i < 256; i ++) {
+        printf(".globl vector%d\n", i);
+        printf("vector%d:\n", i);
+        if ((i < 8 || i > 14) && i != 17) {
+            printf("  pushl $0\n");
+        }
+        printf("  pushl $%d\n", i);
+        printf("  jmp __alltraps\n");
+    }
+    printf("\n");
+    printf("# vector table\n");
+    printf(".data\n");
+    printf(".globl __vectors\n");
+    printf("__vectors:\n");
+    for (i = 0; i < 256; i ++) {
+        printf("  .long vector%d\n", i);
+    }
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/badarg.c b/related_info/lab5/lab5-spoc-discuss/user/badarg.c
new file mode 100644
index 0000000..7b4ffad
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/badarg.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    int pid, exit_code;
+    if ((pid = fork()) == 0) {
+        cprintf("fork ok.\n");
+        int i;
+        for (i = 0; i < 10; i ++) {
+            yield();
+        }
+        exit(0xbeaf);
+    }
+    assert(pid > 0);
+    assert(waitpid(-1, NULL) != 0);
+    assert(waitpid(pid, (void *)0xC0000000) != 0);
+    assert(waitpid(pid, &exit_code) == 0 && exit_code == 0xbeaf);
+    cprintf("badarg pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/badsegment.c b/related_info/lab5/lab5-spoc-discuss/user/badsegment.c
new file mode 100644
index 0000000..cdd9e99
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/badsegment.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <ulib.h>
+
+/* try to load the kernel's TSS selector into the DS register */
+
+int
+main(void) {
+    asm volatile("movw $0x28,%ax; movw %ax,%ds");
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/divzero.c b/related_info/lab5/lab5-spoc-discuss/user/divzero.c
new file mode 100644
index 0000000..16c23d5
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/divzero.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int zero;
+
+int
+main(void) {
+    cprintf("value is %d.\n", 1 / zero);
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/exit.c b/related_info/lab5/lab5-spoc-discuss/user/exit.c
new file mode 100644
index 0000000..c3ac5f8
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/exit.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int magic = -0x10384;
+
+int
+main(void) {
+    int pid, code;
+    cprintf("I am the parent. Forking the child...\n");
+    if ((pid = fork()) == 0) {
+        cprintf("I am the child.\n");
+        yield();
+        yield();
+        yield();
+        yield();
+        yield();
+        yield();
+        yield();
+        exit(magic);
+    }
+    else {
+        cprintf("I am parent, fork a child pid %d\n",pid);
+    }
+    assert(pid > 0);
+    cprintf("I am the parent, waiting now..\n");
+
+    assert(waitpid(pid, &code) == 0 && code == magic);
+    assert(waitpid(pid, &code) != 0 && wait() != 0);
+    cprintf("waitpid %d ok.\n", pid);
+
+    cprintf("exit pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/faultread.c b/related_info/lab5/lab5-spoc-discuss/user/faultread.c
new file mode 100644
index 0000000..6d292e1
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/faultread.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    cprintf("I read %8x from 0.\n", *(unsigned int *)0);
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/faultreadkernel.c b/related_info/lab5/lab5-spoc-discuss/user/faultreadkernel.c
new file mode 100644
index 0000000..53457f6
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/faultreadkernel.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    cprintf("I read %08x from 0xfac00000!\n", *(unsigned *)0xfac00000);
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/forktest.c b/related_info/lab5/lab5-spoc-discuss/user/forktest.c
new file mode 100644
index 0000000..3eda228
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/forktest.c
@@ -0,0 +1,34 @@
+#include <ulib.h>
+#include <stdio.h>
+
+const int max_child = 32;
+
+int
+main(void) {
+    int n, pid;
+    for (n = 0; n < max_child; n ++) {
+        if ((pid = fork()) == 0) {
+            cprintf("I am child %d\n", n);
+            exit(0);
+        }
+        assert(pid > 0);
+    }
+
+    if (n > max_child) {
+        panic("fork claimed to work %d times!\n", n);
+    }
+
+    for (; n > 0; n --) {
+        if (wait() != 0) {
+            panic("wait stopped early\n");
+        }
+    }
+
+    if (wait() == 0) {
+        panic("wait got too many\n");
+    }
+
+    cprintf("forktest pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/forktree.c b/related_info/lab5/lab5-spoc-discuss/user/forktree.c
new file mode 100644
index 0000000..93f28bb
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/forktree.c
@@ -0,0 +1,37 @@
+#include <ulib.h>
+#include <stdio.h>
+#include <string.h>
+
+#define DEPTH 4
+
+void forktree(const char *cur);
+
+void
+forkchild(const char *cur, char branch) {
+    char nxt[DEPTH + 1];
+
+    if (strlen(cur) >= DEPTH)
+        return;
+
+    snprintf(nxt, DEPTH + 1, "%s%c", cur, branch);
+    if (fork() == 0) {
+        forktree(nxt);
+        yield();
+        exit(0);
+    }
+}
+
+void
+forktree(const char *cur) {
+    cprintf("%04x: I am '%s'\n", getpid(), cur);
+
+    forkchild(cur, '0');
+    forkchild(cur, '1');
+}
+
+int
+main(void) {
+    forktree("");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/hello.c b/related_info/lab5/lab5-spoc-discuss/user/hello.c
new file mode 100644
index 0000000..0f05251
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/hello.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    cprintf("Hello world!!.\n");
+    cprintf("I am process %d.\n", getpid());
+    cprintf("hello pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/initcode.S b/related_info/lab5/lab5-spoc-discuss/user/libs/initcode.S
new file mode 100644
index 0000000..77a91d6
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/initcode.S
@@ -0,0 +1,14 @@
+.text
+.globl _start
+_start:
+    # set ebp for backtrace
+    movl $0x0, %ebp
+
+    # move down the esp register
+    # since it may cause page fault in backtrace
+    subl $0x20, %esp
+
+    # call user-program function
+    call umain
+1:  jmp 1b
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/panic.c b/related_info/lab5/lab5-spoc-discuss/user/libs/panic.c
new file mode 100644
index 0000000..783be16
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/panic.c
@@ -0,0 +1,28 @@
+#include <defs.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <ulib.h>
+#include <error.h>
+
+void
+__panic(const char *file, int line, const char *fmt, ...) {
+    // print the 'message'
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("user panic at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+    exit(-E_PANIC);
+}
+
+void
+__warn(const char *file, int line, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("user warning at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/stdio.c b/related_info/lab5/lab5-spoc-discuss/user/libs/stdio.c
new file mode 100644
index 0000000..69b7749
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/stdio.c
@@ -0,0 +1,62 @@
+#include <defs.h>
+#include <stdio.h>
+#include <syscall.h>
+
+/* *
+ * cputch - writes a single character @c to stdout, and it will
+ * increace the value of counter pointed by @cnt.
+ * */
+static void
+cputch(int c, int *cnt) {
+    sys_putc(c);
+    (*cnt) ++;
+}
+
+/* *
+ * vcprintf - format a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want cprintf() instead.
+ * */
+int
+vcprintf(const char *fmt, va_list ap) {
+    int cnt = 0;
+    vprintfmt((void*)cputch, &cnt, fmt, ap);
+    return cnt;
+}
+
+/* *
+ * cprintf - formats a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ * */
+int
+cprintf(const char *fmt, ...) {
+    va_list ap;
+
+    va_start(ap, fmt);
+    int cnt = vcprintf(fmt, ap);
+    va_end(ap);
+
+    return cnt;
+}
+
+/* *
+ * cputs- writes the string pointed by @str to stdout and
+ * appends a newline character.
+ * */
+int
+cputs(const char *str) {
+    int cnt = 0;
+    char c;
+    while ((c = *str ++) != '\0') {
+        cputch(c, &cnt);
+    }
+    cputch('\n', &cnt);
+    return cnt;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.c b/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.c
new file mode 100644
index 0000000..7bdc0d2
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.c
@@ -0,0 +1,72 @@
+#include <defs.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <syscall.h>
+
+#define MAX_ARGS            5
+
+static inline int
+syscall(int num, ...) {
+    va_list ap;
+    va_start(ap, num);
+    uint32_t a[MAX_ARGS];
+    int i, ret;
+    for (i = 0; i < MAX_ARGS; i ++) {
+        a[i] = va_arg(ap, uint32_t);
+    }
+    va_end(ap);
+
+    asm volatile (
+        "int %1;"
+        : "=a" (ret)
+        : "i" (T_SYSCALL),
+          "a" (num),
+          "d" (a[0]),
+          "c" (a[1]),
+          "b" (a[2]),
+          "D" (a[3]),
+          "S" (a[4])
+        : "cc", "memory");
+    return ret;
+}
+
+int
+sys_exit(int error_code) {
+    return syscall(SYS_exit, error_code);
+}
+
+int
+sys_fork(void) {
+    return syscall(SYS_fork);
+}
+
+int
+sys_wait(int pid, int *store) {
+    return syscall(SYS_wait, pid, store);
+}
+
+int
+sys_yield(void) {
+    return syscall(SYS_yield);
+}
+
+int
+sys_kill(int pid) {
+    return syscall(SYS_kill, pid);
+}
+
+int
+sys_getpid(void) {
+    return syscall(SYS_getpid);
+}
+
+int
+sys_putc(int c) {
+    return syscall(SYS_putc, c);
+}
+
+int
+sys_pgdir(void) {
+    return syscall(SYS_pgdir);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.h b/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.h
new file mode 100644
index 0000000..1ccfbc4
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/syscall.h
@@ -0,0 +1,14 @@
+#ifndef __USER_LIBS_SYSCALL_H__
+#define __USER_LIBS_SYSCALL_H__
+
+int sys_exit(int error_code);
+int sys_fork(void);
+int sys_wait(int pid, int *store);
+int sys_yield(void);
+int sys_kill(int pid);
+int sys_getpid(void);
+int sys_putc(int c);
+int sys_pgdir(void);
+
+#endif /* !__USER_LIBS_SYSCALL_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.c b/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.c
new file mode 100644
index 0000000..329da5c
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.c
@@ -0,0 +1,48 @@
+#include <defs.h>
+#include <syscall.h>
+#include <stdio.h>
+#include <ulib.h>
+
+void
+exit(int error_code) {
+    sys_exit(error_code);
+    cprintf("BUG: exit failed.\n");
+    while (1);
+}
+
+int
+fork(void) {
+    return sys_fork();
+}
+
+int
+wait(void) {
+    return sys_wait(0, NULL);
+}
+
+int
+waitpid(int pid, int *store) {
+    return sys_wait(pid, store);
+}
+
+void
+yield(void) {
+    sys_yield();
+}
+
+int
+kill(int pid) {
+    return sys_kill(pid);
+}
+
+int
+getpid(void) {
+    return sys_getpid();
+}
+
+//print_pgdir - print the PDT&PT
+void
+print_pgdir(void) {
+    sys_pgdir();
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.h b/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.h
new file mode 100644
index 0000000..1bb5763
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/ulib.h
@@ -0,0 +1,36 @@
+#ifndef __USER_LIBS_ULIB_H__
+#define __USER_LIBS_ULIB_H__
+
+#include <defs.h>
+
+void __warn(const char *file, int line, const char *fmt, ...);
+void __noreturn __panic(const char *file, int line, const char *fmt, ...);
+
+#define warn(...)                                       \
+    __warn(__FILE__, __LINE__, __VA_ARGS__)
+
+#define panic(...)                                      \
+    __panic(__FILE__, __LINE__, __VA_ARGS__)
+
+#define assert(x)                                       \
+    do {                                                \
+        if (!(x)) {                                     \
+            panic("assertion failed: %s", #x);          \
+        }                                               \
+    } while (0)
+
+// static_assert(x) will generate a compile-time error if 'x' is false.
+#define static_assert(x)                                \
+    switch (x) { case 0: case (x): ; }
+
+void __noreturn exit(int error_code);
+int fork(void);
+int wait(void);
+int waitpid(int pid, int *store);
+void yield(void);
+int kill(int pid);
+int getpid(void);
+void print_pgdir(void);
+
+#endif /* !__USER_LIBS_ULIB_H__ */
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/libs/umain.c b/related_info/lab5/lab5-spoc-discuss/user/libs/umain.c
new file mode 100644
index 0000000..c352072
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/libs/umain.c
@@ -0,0 +1,10 @@
+#include <ulib.h>
+
+int main(void);
+
+void
+umain(void) {
+    int ret = main();
+    exit(ret);
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/pgdir.c b/related_info/lab5/lab5-spoc-discuss/user/pgdir.c
new file mode 100644
index 0000000..09fd7e3
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/pgdir.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    cprintf("I am %d, print pgdir.\n", getpid());
+    print_pgdir();
+    cprintf("pgdir pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/softint.c b/related_info/lab5/lab5-spoc-discuss/user/softint.c
new file mode 100644
index 0000000..2f14d15
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/softint.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    asm volatile("int $14");
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/spin.c b/related_info/lab5/lab5-spoc-discuss/user/spin.c
new file mode 100644
index 0000000..91581e5
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/spin.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <ulib.h>
+
+int
+main(void) {
+    int pid, ret;
+    cprintf("I am the parent. Forking the child...\n");
+    if ((pid = fork()) == 0) {
+        cprintf("I am the child. spinning ...\n");
+        while (1);
+    }
+    cprintf("I am the parent. Running the child...\n");
+
+    yield();
+    yield();
+    yield();
+
+    cprintf("I am the parent.  Killing the child...\n");
+
+    assert((ret = kill(pid)) == 0);
+    cprintf("kill returns %d\n", ret);
+
+    assert((ret = waitpid(pid, NULL)) == 0);
+    cprintf("wait returns %d\n", ret);
+
+    cprintf("spin may pass.\n");
+    return 0;
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/testbss.c b/related_info/lab5/lab5-spoc-discuss/user/testbss.c
new file mode 100644
index 0000000..14dc6e1
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/testbss.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <ulib.h>
+
+#define ARRAYSIZE (1024*1024)
+
+uint32_t bigarray[ARRAYSIZE];
+
+int
+main(void) {
+    cprintf("Making sure bss works right...\n");
+    int i;
+    for (i = 0; i < ARRAYSIZE; i ++) {
+        if (bigarray[i] != 0) {
+            panic("bigarray[%d] isn't cleared!\n", i);
+        }
+    }
+    for (i = 0; i < ARRAYSIZE; i ++) {
+        bigarray[i] = i;
+    }
+    for (i = 0; i < ARRAYSIZE; i ++) {
+        if (bigarray[i] != i) {
+            panic("bigarray[%d] didn't hold its value!\n", i);
+        }
+    }
+
+    cprintf("Yes, good.  Now doing a wild write off the end...\n");
+    cprintf("testbss may pass.\n");
+
+    bigarray[ARRAYSIZE + 1024] = 0;
+    asm volatile ("int $0x14");
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/waitkill.c b/related_info/lab5/lab5-spoc-discuss/user/waitkill.c
new file mode 100644
index 0000000..9bb3f80
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/waitkill.c
@@ -0,0 +1,59 @@
+#include <ulib.h>
+#include <stdio.h>
+
+void
+do_yield(void) {
+    yield();
+    yield();
+    yield();
+    yield();
+    yield();
+    yield();
+}
+
+int parent, pid1, pid2;
+
+void
+loop(void) {
+    cprintf("child 1.\n");
+    while (1);
+}
+
+void
+work(void) {
+    cprintf("child 2.\n");
+    do_yield();
+    if (kill(parent) == 0) {
+        cprintf("kill parent ok.\n");
+        do_yield();
+        if (kill(pid1) == 0) {
+            cprintf("kill child1 ok.\n");
+            exit(0);
+        }
+    }
+    exit(-1);
+}
+
+int
+main(void) {
+    parent = getpid();
+    if ((pid1 = fork()) == 0) {
+        loop();
+    }
+
+    assert(pid1 > 0);
+
+    if ((pid2 = fork()) == 0) {
+        work();
+    }
+    if (pid2 > 0) {
+        cprintf("wait child 1.\n");
+        waitpid(pid1, NULL);
+        panic("waitpid %d returns\n", pid1);
+    }
+    else {
+        kill(pid1);
+    }
+    panic("FAIL: T.T\n");
+}
+
diff --git a/related_info/lab5/lab5-spoc-discuss/user/yield.c b/related_info/lab5/lab5-spoc-discuss/user/yield.c
new file mode 100644
index 0000000..a19890d
--- /dev/null
+++ b/related_info/lab5/lab5-spoc-discuss/user/yield.c
@@ -0,0 +1,16 @@
+#include <ulib.h>
+#include <stdio.h>
+
+int
+main(void) {
+    int i;
+    cprintf("Hello, I am process %d.\n", getpid());
+    for (i = 0; i < 5; i ++) {
+        yield();
+        cprintf("Back in process %d, iteration %d.\n", getpid(), i);
+    }
+    cprintf("All done in process %d.\n", getpid());
+    cprintf("yield pass.\n");
+    return 0;
+}
+