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/* $OpenBSD: srt0.S,v 1.17 2022/12/08 01:25:45 guenther Exp $ */
/*
* Copyright (c) 1997 Michael Shalayeff
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <machine/asm.h>
#include <assym.h>
#define BOOTSTACK 0xfffc
.globl end
.globl edata
.globl boot
.globl _rtt
.globl bios_bootdev
.globl pmm_init
.globl Gdtr
.text
.align 16
.code16
.globl _start
_start:
popl %eax
cmpl $BOOTMAGIC, %eax
je 1f
#ifdef DEBUG
movl $0xb80a0, %ebx
addr32 movl $0x07420742, (%ebx)
#endif
1:
popl %edx
cli
pushl %cs
popl %ds
addr32 data32 lgdt (Gdtr - LINKADDR)
movl %cr0, %eax
orl $CR0_PE, %eax
data32 movl %eax, %cr0
data32 ljmp $8, $1f
1:
.code32
movl $0x10,%eax
mov %ax,%ds
mov %ax,%ss
mov %ax,%es
mov %ax,%fs
mov %ax,%gs
movl $BOOTSTACK,%esp
pushl %edx
movl %edx, bios_bootdev
/* Now do it all */
#ifdef DEBUG
movl $0xb80a4, %ebx
movl $0x07520752, (%ebx)
#endif
/* zero .bss */
xorl %eax, %eax
movl $end, %ecx
subl $edata,%ecx
movl $edata, %edi
cld
rep; stosb
call pmm_init
call boot
jmp _rtt
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