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 #include <asm.inc>
  21
  22
  23         .text
  24         .code16
  25
  26 #define ASM
  27 #include <arch.h>
  28
  29 PUBLIC ChainLoadBiosBootSectorCode
  30 ChainLoadBiosBootSectorCode:
  31         .code64
  32
  33         call x86_64_SwitchToReal
  34         .code16
  35
  36         /* Set the boot drive */
  37         mov dl, BootDrive
  38
  39         /* Load segment registers */
  40         cli
  41         mov bx, 0x0000
  42         mov ds, bx
  43         mov es, bx
  44         mov fs, bx
  45         mov gs, bx
  46         mov ss, bx
  47         mov sp, 0x7C00
  48
  49 //      ljmpl   $0x0000,$0x7C00
  50         jmp 0x7c00:0x0000
  51
  52 PUBLIC SoftReboot
  53 SoftReboot:
  54         .code64
  55
  56         call    x86_64_SwitchToReal
  57         .code16
  58
  59         mov ax, 0x40
  60         mov ds, ax
  61         mov si, 0x72
  62
  63         // Set the word at location 40:72 to 1234h
  64         mov word ptr [si], 0x1234
  65
  66         // and jump to location FFFF:0 in ROM
  67 //      ljmpl   $0xFFFF,$0x0000
  68         jmp 0xffff: 0x0000