diff --git a/related_info/lab1/pmbootloader/Makefile b/related_info/lab1/pmbootloader/Makefile new file mode 100644 index 0000000..ab492e4 --- /dev/null +++ b/related_info/lab1/pmbootloader/Makefile @@ -0,0 +1,12 @@ +all:pmboot +pmboot.s: pmboot.S + gcc -E pmboot.S > pmboot.s +pmboot.o: pmboot.s + as -o pmboot.o pmboot.s +pmboot: pmboot.o + ld --oformat binary -N -e start -Ttext 0x7c00 -o pmboot pmboot.o +run: pmboot + qemu-system-i386 -fda pmboot +.PHONY: clean +clean: + rm pmboot.o pmboot pmboot.s diff --git a/related_info/lab1/pmbootloader/pmboot.S b/related_info/lab1/pmbootloader/pmboot.S new file mode 100644 index 0000000..729cef0 --- /dev/null +++ b/related_info/lab1/pmbootloader/pmboot.S @@ -0,0 +1,81 @@ +#define Descriptor(base,lim,type)\ +.word lim&0xffff;\ +.word base&0xffff;\ +.byte (base>>16)&0xff;\ +.word ((lim>>8)&0xf00)|(type&0x0f0ff);\ +.byte ((base>>24)&0xff) + +DA_C = 0x98 +DA_32 = 0x4000 +DA_DRW = 0x92 + +.text +.globl start +.code16 +start: + jmpl $0x0, $code + +GDT_START: +Descriptor_DUMMY:Descriptor(0x0,0x0,0x0) +Descript_CODE32 :Descriptor(0x0,0xffffffff,DA_C+DA_32) +Descriptor_VIDEO:Descriptor(0xb8000,0x0ffff,DA_DRW) +GDT_END: + +GdtPtr: + .word (GDT_END-GDT_START)-1 # so does gdt + .long GDT_START # This will be rewrite by code. +msg: + .string "Hello world!" +code: + mov %cs,%ax + mov %ax,%ds + mov %ax,%es + mov %ax,%ss + mov $0x8000,%sp + /*显示HelloWorld字符串*/ + mov $msg ,%ax + mov %ax ,%bp + mov $12 ,%cx + mov $0x1301,%ax + mov $0x000c,%bx + mov $0 ,%dl + + int $0x10 + +/*加载gdtr即将全局描述符表gdt的首地址和gdt的界限赋给gdtr寄存器*/ + lgdt GdtPtr + +/*关中断*/ + cli + +/*打开地址线A20*/ + inb $0x92,%al + or $0x02,%al + outb %al,$0x92 + +/*设置cr0寄存器,切换到保护模式*/ + movl %cr0,%eax + or $1,%eax + movl %eax,%cr0 + + +/*真正进入保护模式,执行此命令后CS=0x8,IP=LABEL_SEG_CODE32的偏移地址*/ + ljmp $0x8,$(LABEL_SEG_CODE32) +/*此时CS:IP=全局描述符表中第1(0x8>>3)项描述符给出的段基址+LABEL_SEG_CODE32的偏移地址*/ + + +LABEL_SEG_CODE32: +.align 32 +.code32 + movw $0x10,%ax + movw %ax,%gs + movl $((80*11+79)*2),%edi/*第11行,79列*/ + movb $0x0c,%ah/*高四位表示黑底,低四位表示红字*/ + movb $'P',%al/*显示的字符*/ + movw %ax,%gs:(%edi) + +loop2: + jmp loop2 + +.org 0x1fe, 0x90 +.word 0xaa55 diff --git a/related_info/lab1/pmbootloader/pmboot.md b/related_info/lab1/pmbootloader/pmboot.md new file mode 100644 index 0000000..3c26b32 --- /dev/null +++ b/related_info/lab1/pmbootloader/pmboot.md @@ -0,0 +1,8 @@ +From http://blog.csdn.net/guocaigao/article/details/8477929 + +A toy protect-mode bootloader can display string in real/protect mode of x86. + +Try +``` +make run +```