core/localboot.c

   1 /* -----------------------------------------------------------------------
   2  *
   3  *   Copyright 1999-2008 H. Peter Anvin - All Rights Reserved
   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, Inc., 51 Franklin St, Fifth Floor,
   8  *   Boston MA 02110-1301, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * -----------------------------------------------------------------------
  12  */
  13 #include <sys/cpu.h>
  14 #include <sys/io.h>
  15 #include <string.h>
  16 #include <core.h>
  17 #include <fs.h>
  18 #include <bios.h>
  19 #include <graphics.h>
  20
  21 /*
  22  * localboot.c
  23  *
  24  * Boot from a local disk, or invoke INT 18h.
  25  */
  26
  27 #define LOCALBOOT_MSG   "Booting from local disk..."
  28
  29 #define retry_count     16
  30
  31 extern void local_boot16(void);
  32
  33 /*
  34  * Boot a specified local disk.  AX specifies the BIOS disk number; or
  35  * -1 in case we should execute INT 18h ("next device.")
  36  */
  37 void local_boot(int16_t ax)
  38 {
  39         com32sys_t ireg, oreg;
  40         int i;
  41
  42         syslinux_force_text_mode();
  43
  44         writestr(LOCALBOOT_MSG);
  45         crlf();
  46         cleanup_hardware();
  47
  48         if (ax == -1) {
  49                 /* Hope this does the right thing */
  50                 __intcall(0x18, &zero_regs, NULL);
  51
  52                 /* If we returned, oh boy... */
  53                 kaboom();
  54         }
  55
  56         /*
  57          * Load boot sector from the specified BIOS device and jump to
  58          * it.
  59          */
  60         ireg.edx.b[0] = ax & 0xff;
  61         ireg.eax.w[0] = 0;      /* Reset drive */
  62         __intcall(0x13, &ireg, NULL);
  63
  64         ireg.eax.w[0] = 0x0201; /* Read one sector */
  65         ireg.ecx.w[0] = 0x0001; /* C/H/S = 0/0/1 (first sector) */
  66         ireg.ebx.w[0] = OFFS(trackbuf);
  67         ireg.es = SEG(trackbuf);
  68
  69         for (i = 0; i < retry_count; i++) {
  70                 __intcall(0x13, &ireg, &oreg);
  71
  72                 if (!(oreg.eflags.l & EFLAGS_CF))
  73                         break;
  74         }
  75
  76         if (i == retry_count)
  77                 kaboom();
  78
  79         cli();                  /* Abandon hope, ye who enter here */
  80         memcpy((void *)0x07C00, trackbuf, 512);
  81
  82         ireg.esi.w[0] = OFFS(trackbuf);
  83         ireg.edi.w[0] = 0x07C00;
  84         ireg.edx.w[0] = ax;
  85         call16(local_boot16, &ireg, NULL);
  86 }
  87
  88 void pm_local_boot(com32sys_t *regs)
  89 {
  90         local_boot(regs->eax.w[0]);
  91 }