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Annotation of sys/arch/i386/stand/boot/srt0.S, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: srt0.S,v 1.14 2003/11/22 09:18:25 grange 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:        .code16
                     44:        .globl  _start
                     45: _start:
                     46:        popl %eax
                     47:        cmpl $BOOTMAGIC, %eax
                     48:        je      1f
                     49: #ifdef DEBUG
                     50:        movl    $0xb80a0, %ebx
                     51:        addr32 movl $0x07420742, (%ebx)
                     52: #endif
                     53: 1:
                     54:        popl %edx
                     55:        cli
                     56:        pushl   %cs
                     57:        popl    %ds
                     58:        addr32 data32 lgdt      (Gdtr - LINKADDR)
                     59:        movl    %cr0, %eax
                     60:        orl $CR0_PE, %eax
                     61:        data32 movl %eax, %cr0
                     62:        data32 ljmp $8, $1f
                     63: 1:
                     64:        .code32
                     65:        movl    $0x10,%eax
                     66:        mov     %ax,%ds
                     67:        mov     %ax,%ss
                     68:        mov     %ax,%es
                     69:        mov     %ax,%fs
                     70:        mov     %ax,%gs
                     71:        movl    $BOOTSTACK,%esp
                     72:        pushl   %edx
                     73:        movl    %edx, _C_LABEL(bios_bootdev)
                     74:
                     75:        /* Now do it all */
                     76:        call    _ASM_LABEL(pmm_init)
                     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    _C_LABEL(boot)
                     90:
                     91:        jmp     _C_LABEL(_rtt)
                     92: