i386/boot1u/boot1u.s

   1 /*
   2  * Copyright (c) 1999-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 2.0 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Mach Operating System
  26  * Copyright (c) 1990 Carnegie-Mellon University
  27  * Copyright (c) 1989 Carnegie-Mellon University
  28  * All rights reserved.  The CMU software License Agreement specifies
  29  * the terms and conditions for use and redistribution.
  30  */
  31
  32 /*
  33  * bootu() -- second stage boot.
  34  *
  35  * This function must be located at 0:BOOTER_ADDR and will be called
  36  * by boot1 or by NBP.
  37  */
  38
  39 #include <architecture/i386/asm_help.h>
  40 #include "memory.h"
  41
  42 #define data32  .byte 0x66
  43 #define addr32  .byte 0x67
  44 #define retf    .byte 0xcb
  45
  46     .file "bootu.s"
  47
  48     .data
  49
  50 EXPORT(_chainbootdev)  .byte 0x80
  51 EXPORT(_chainbootflag) .byte 0x00
  52
  53 .text
  54
  55 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  56 # Booter entry point. Called by the MBR booter.
  57 # This routine must be the first in the TEXT segment.
  58 #
  59 # Arguments:
  60 #   DL    = Boot drive number
  61 #   SI    = Pointer to partition table entry.
  62 #
  63 LABEL(bootu)
  64     pushl   %ecx                # Save general purpose registers
  65     pushl   %ebx
  66     pushl   %ebp
  67     pushl   %esi
  68     pushl   %edi
  69     push    %ds                 # Save DS, ES
  70     push    %es
  71
  72     mov     %cs, %ax            # Update segment registers.
  73     mov     %ax, %ds            # Set DS and ES to match CS
  74     mov     %ax, %es
  75
  76     xor     %ebx, %ebx
  77     mov     %si, %bx            # save si
  78
  79     data32
  80     call    __switch_stack      # Switch to new stack
  81
  82     data32
  83     call    __real_to_prot      # Enter protected mode.
  84
  85     # We are now in 32-bit protected mode.
  86     # Transfer execution to C by calling boot().
  87
  88     pushl   %ebx
  89     pushl   %edx                # bootdev
  90     call    _boot
  91
  92 start_boot2:
  93     xorl    %edx, %edx
  94     movb    _chainbootdev, %dl  # Setup DL with the BIOS device number
  95
  96     call    __prot_to_real      # Back to real mode.
  97
  98     data32
  99     call    __switch_stack      # Restore original stack
 100
 101     pop     %es                 # Restore original ES and DS
 102     pop     %ds
 103     popl    %edi                # Restore all general purpose registers
 104     popl    %esi                # except EAX.
 105     popl    %ebp
 106     popl    %ebx
 107     popl    %ecx
 108
 109     data32
 110     ljmp    $0x2000, $0x0200    # Jump to boot code already in memory
 111