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49 líneas
1.1 KiB
49 líneas
1.1 KiB
#include <mmu.h>
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#include <memlayout.h>
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#define REALLOC(x) (x - KERNBASE)
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.text
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.globl kern_entry
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kern_entry:
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# reload temperate gdt (second time) to remap all physical memory
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# virtual_addr 0~4G=linear_addr&physical_addr -KERNBASE~4G-KERNBASE
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lgdt REALLOC(__gdtdesc)
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movl $KERNEL_DS, %eax
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %ss
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ljmp $KERNEL_CS, $relocated
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relocated:
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# set ebp, esp
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movl $0x0, %ebp
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# the kernel stack region is from bootstack -- bootstacktop,
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# the kernel stack size is KSTACKSIZE (8KB)defined in memlayout.h
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movl $bootstacktop, %esp
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# now kernel stack is ready , call the first C function
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call kern_init
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# should never get here
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spin:
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jmp spin
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.data
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.align PGSIZE
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.globl bootstack
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bootstack:
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.space KSTACKSIZE
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.globl bootstacktop
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bootstacktop:
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.align 4
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__gdt:
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SEG_NULL
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SEG_ASM(STA_X | STA_R, - KERNBASE, 0xFFFFFFFF) # code segment
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SEG_ASM(STA_W, - KERNBASE, 0xFFFFFFFF) # data segment
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__gdtdesc:
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.word 0x17 # sizeof(__gdt) - 1
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.long REALLOC(__gdt)
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