54 lines
674 B
ArmAsm
54 lines
674 B
ArmAsm
.file "srt0.S"
|
|
|
|
#include "def.h"
|
|
|
|
.globl end
|
|
.globl edata
|
|
.globl Gdtr
|
|
.globl boot
|
|
.globl pmode_init
|
|
|
|
.text
|
|
.code16
|
|
.align 16
|
|
.globl _start
|
|
_start:
|
|
popl %eax
|
|
cmpl $BOOTMAGIC, %eax
|
|
je 1f
|
|
|
|
1:
|
|
popl %edx
|
|
// load GDT
|
|
cli
|
|
pushl %cs
|
|
popl %ds
|
|
addr32 data32 lgdt (Gdtr - LINKADDR)
|
|
movl %cr0, %eax
|
|
// enable protected mode
|
|
orl $CR0_PE, %eax
|
|
data32 movl %eax, %cr0
|
|
data32 ljmp $S32TEXT, $1f
|
|
|
|
1:
|
|
.code32
|
|
movl $0x10, %eax
|
|
mov %ax, %ds
|
|
mov %ax, %ss
|
|
mov %ax, %es
|
|
mov %ax, %fs
|
|
mov %ax, %gs
|
|
movl $BOOTSTACKOFF, %esp
|
|
pushl %edx
|
|
|
|
// fill 0 .bss
|
|
xorl %eax, %eax
|
|
movl $end, %ecx
|
|
subl $edata, %ecx
|
|
movl $edata, %edi
|
|
cld
|
|
rep; stosb
|
|
|
|
call pmode_init
|
|
call boot
|