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 <syslinux/video.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 __export void local_boot(int16_t ax)
  38 {
  39         com32sys_t ireg, oreg;
  40         int i;
  41
  42         memset(&ireg, 0, sizeof(ireg));
  43         syslinux_force_text_mode();
  44
  45         writestr(LOCALBOOT_MSG);
  46         crlf();
  47         cleanup_hardware();
  48
  49         if (ax == -1) {
  50                 /* Hope this does the right thing */
  51                 __intcall(0x18, &zero_regs, NULL);
  52
  53                 /* If we returned, oh boy... */
  54                 kaboom();
  55         }
  56
  57         /*
  58          * Load boot sector from the specified BIOS device and jump to
  59          * it.
  60          */
  61         memset(&ireg, 0, sizeof ireg);
  62         ireg.edx.b[0] = ax & 0xff;
  63         ireg.eax.w[0] = 0;      /* Reset drive */
  64         __intcall(0x13, &ireg, NULL);
  65
  66         memset(&ireg, 0, sizeof(ireg));
  67         ireg.eax.w[0] = 0x0201; /* Read one sector */
  68         ireg.ecx.w[0] = 0x0001; /* C/H/S = 0/0/1 (first sector) */
  69         ireg.ebx.w[0] = OFFS(trackbuf);
  70         ireg.es = SEG(trackbuf);
  71
  72         for (i = 0; i < retry_count; i++) {
  73                 __intcall(0x13, &ireg, &oreg);
  74
  75                 if (!(oreg.eflags.l & EFLAGS_CF))
  76                         break;
  77         }
  78
  79         if (i == retry_count)
  80                 kaboom();
  81
  82         cli();                  /* Abandon hope, ye who enter here */
  83         memcpy((void *)0x07C00, trackbuf, 512);
  84
  85         ireg.esi.w[0] = OFFS(trackbuf);
  86         ireg.edi.w[0] = 0x07C00;
  87         ireg.edx.w[0] = ax;
  88         call16(local_boot16, &ireg, NULL);
  89 }
  90
  91 void pm_local_boot(com32sys_t *regs)
  92 {
  93         local_boot(regs->eax.w[0]);
  94 }