1/* $OpenBSD: srt0.S,v 1.3 2012/10/12 15:00:32 jsing Exp $ */ 2 3/* 4 * Copyright (c) 1997 Michael Shalayeff 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 */ 29#include <machine/asm.h> 30#include <assym.h> 31 32#define BOOTSTACK 0xfffc 33 34 .globl _C_LABEL(end) 35 .globl _C_LABEL(edata) 36 .globl _C_LABEL(boot) 37 .globl _C_LABEL(_rtt) 38 .globl _C_LABEL(bios_bootdev) 39 .globl _ASM_LABEL(pmm_init) 40 .globl Gdtr 41 42 .text 43 .align 16 44 .code16 45 .globl _start 46_start: 47 popl %eax 48 cmpl $BOOTMAGIC, %eax 49 je 1f 50#ifdef DEBUG 51 movl $0xb80a0, %ebx 52 addr32 movl $0x07420742, (%ebx) 53#endif 541: 55 popl %edx 56 cli 57 pushl %cs 58 popl %ds 59 addr32 data32 lgdt (Gdtr - LINKADDR) 60 movl %cr0, %eax 61 orl $CR0_PE, %eax 62 data32 movl %eax, %cr0 63 data32 ljmp $8, $1f 641: 65 .code32 66 movl $0x10,%eax 67 mov %ax,%ds 68 mov %ax,%ss 69 mov %ax,%es 70 mov %ax,%fs 71 mov %ax,%gs 72 movl $BOOTSTACK,%esp 73 pushl %edx 74 movl %edx, _C_LABEL(bios_bootdev) 75 76 /* Now do it all */ 77#ifdef DEBUG 78 movl $0xb80a4, %ebx 79 movl $0x07520752, (%ebx) 80#endif 81 /* zero .bss */ 82 xorl %eax, %eax 83 movl $_C_LABEL(end), %ecx 84 subl $_C_LABEL(edata),%ecx 85 movl $_C_LABEL(edata), %edi 86 cld 87 rep; stosb 88 89 call _ASM_LABEL(pmm_init) 90 call _C_LABEL(boot) 91 92 jmp _C_LABEL(_rtt) 93