1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
.code16gcc
#include "assembly.h"
.section .init
ENTRY(pm_entry)
xor %ax, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss
mov $0x7c00, %sp
mov %cr0, %eax
or $1, %eax
mov %eax, %cr0
lgdtl %cs:0xff80 + gdt32_descr - pm_entry
ljmpl $8, $0xffffff80 + 2f - pm_entry
2:
.code32
mov $16, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss
ljmp $8, $0xffff0000
gdt32:
.quad 0
.quad 0x00cf9b000000ffff // flat 32-bit code segment
.quad 0x00cf93000000ffff // flat 32-bit data segment
.quad 0x008f9b0f0000ffff // 16-bit code segment at 0xF0000
gdt32_end:
gdt32_descr:
.word gdt32_end - gdt32 - 1
.long 0xffffff80 + gdt32 - pm_entry
ENTRY_END(pm_entry)
.code16gcc
.section .resetvector
jmp pm_entry
|
