boot/freeldr/freeldr/arch/amd64/boot.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  Brian Palmer  <brianp@sginet.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20         .text
  21         .code16
  22
  23 #define ASM
  24 #include <arch.h>
  25
  26
  27 EXTERN(ChainLoadBiosBootSectorCode)
  28         .code64
  29
  30         call x86_64_SwitchToReal
  31         .code16
  32
  33         /* Set the boot drive */
  34         mov dl, BootDrive
  35
  36         /* Load segment registers */
  37         cli
  38         mov bx, 0x0000
  39         mov ds, bx
  40         mov es, bx
  41         mov fs, bx
  42         mov gs, bx
  43         mov ss, bx
  44         mov sp, 0x7C00
  45
  46 //      ljmpl   $0x0000,$0x7C00
  47         jmp 0x7c00:0x0000
  48
  49 EXTERN(SoftReboot)
  50         .code64
  51
  52         call    x86_64_SwitchToReal
  53         .code16
  54
  55         mov ax, 0x40
  56         mov ds, ax
  57         mov si, 0x72
  58
  59         // Set the word at location 40:72 to 1234h
  60         mov word ptr [si], 0x1234
  61
  62         // and jump to location FFFF:0 in ROM
  63 //      ljmpl   $0xFFFF,$0x0000
  64         jmp 0xffff: 0x0000