common.c

i386的bootloader源码grub

/* common.c - miscellaneous shared variables and routines */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2004  Free Software Foundation, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <shared.h>

#ifdef SUPPORT_DISKLESS
# define GRUB	1
# include <etherboot.h>
#endif

/*
 *  Shared BIOS/boot data.
 */

struct multiboot_info mbi;
unsigned long saved_drive;
unsigned long saved_partition;
unsigned long cdrom_drive;
#ifndef STAGE1_5
unsigned long saved_mem_upper;

/* This saves the maximum size of extended memory (in KB).  */
unsigned long extended_memory;
#endif

/*
 *  Error code stuff.
 */

grub_error_t errnum = ERR_NONE;

#ifndef STAGE1_5

char *err_list[] =
{
  [ERR_NONE] = 0,
  [ERR_BAD_ARGUMENT] = "Invalid argument",
  [ERR_BAD_FILENAME] =
  "Filename must be either an absolute pathname or blocklist",
  [ERR_BAD_FILETYPE] = "Bad file or directory type",
  [ERR_BAD_GZIP_DATA] = "Bad or corrupt data while decompressing file",
  [ERR_BAD_GZIP_HEADER] = "Bad or incompatible header in compressed file",
  [ERR_BAD_PART_TABLE] = "Partition table invalid or corrupt",
  [ERR_BAD_VERSION] = "Mismatched or corrupt version of stage1/stage2",
  [ERR_BELOW_1MB] = "Loading below 1MB is not supported",
  [ERR_BOOT_COMMAND] = "Kernel must be loaded before booting",
  [ERR_BOOT_FAILURE] = "Unknown boot failure",
  [ERR_BOOT_FEATURES] = "Unsupported Multiboot features requested",
  [ERR_DEV_FORMAT] = "Unrecognized device string",
  [ERR_DEV_NEED_INIT] = "Device not initialized yet",
  [ERR_DEV_VALUES] = "Invalid device requested",
  [ERR_EXEC_FORMAT] = "Invalid or unsupported executable format",
  [ERR_FILELENGTH] =
  "Filesystem compatibility error, cannot read whole file",
  [ERR_FILE_NOT_FOUND] = "File not found",
  [ERR_FSYS_CORRUPT] = "Inconsistent filesystem structure",
  [ERR_FSYS_MOUNT] = "Cannot mount selected partition",
  [ERR_GEOM] = "Selected cylinder exceeds maximum supported by BIOS",
  [ERR_NEED_LX_KERNEL] = "Linux kernel must be loaded before initrd",
  [ERR_NEED_MB_KERNEL] = "Multiboot kernel must be loaded before modules",
  [ERR_NO_DISK] = "Selected disk does not exist",
  [ERR_NO_DISK_SPACE] = "No spare sectors on the disk",
  [ERR_NO_PART] = "No such partition",
  [ERR_NUMBER_OVERFLOW] = "Overflow while parsing number",
  [ERR_NUMBER_PARSING] = "Error while parsing number",
  [ERR_OUTSIDE_PART] = "Attempt to access block outside partition",
  [ERR_PRIVILEGED] = "Must be authenticated",
  [ERR_READ] = "Disk read error",
  [ERR_SYMLINK_LOOP] = "Too many symbolic links",
  [ERR_UNALIGNED] = "File is not sector aligned",
  [ERR_UNRECOGNIZED] = "Unrecognized command",
  [ERR_WONT_FIT] = "Selected item cannot fit into memory",
  [ERR_WRITE] = "Disk write error",
};


/* static for BIOS memory map fakery */
static struct AddrRangeDesc fakemap[3] =
{
  {20, 0, 0, MB_ARD_MEMORY},
  {20, 0x100000, 0, MB_ARD_MEMORY},
  {20, 0x1000000, 0, MB_ARD_MEMORY}
};

/* A big problem is that the memory areas aren't guaranteed to be:
   (1) contiguous, (2) sorted in ascending order, or (3) non-overlapping.
   Thus this kludge.  */
static unsigned long
mmap_avail_at (unsigned long bottom)
{
  unsigned long long top;
  unsigned long addr;
  int cont;
  
  top = bottom;
  do
    {
      for (cont = 0, addr = mbi.mmap_addr;
	   addr < mbi.mmap_addr + mbi.mmap_length;
	   addr += *((unsigned long *) addr) + 4)
	{
	  struct AddrRangeDesc *desc = (struct AddrRangeDesc *) addr;
	  
	  if (desc->Type == MB_ARD_MEMORY
	      && desc->BaseAddr <= top
	      && desc->BaseAddr + desc->Length > top)
	    {
	      top = desc->BaseAddr + desc->Length;
	      cont++;
	    }
	}
    }
  while (cont);

  /* For now, GRUB assumes 32bits addresses, so...  */
  if (top > 0xFFFFFFFF)
    top = 0xFFFFFFFF;
  
  return (unsigned long) top - bottom;
}
#endif /* ! STAGE1_5 */

/* This queries for BIOS information.  */
void
init_bios_info (void)
{
#ifndef STAGE1_5
  unsigned long cont, memtmp, addr;
  int drive;
#endif

  /*
   *  Get information from BIOS on installed RAM.
   */

  mbi.mem_lower = get_memsize (0);
  mbi.mem_upper = get_memsize (1);

#ifndef STAGE1_5
  /*
   *  We need to call this somewhere before trying to put data
   *  above 1 MB, since without calling it, address line 20 will be wired
   *  to 0.  Not too desirable.
   */

  gateA20 (1);

  /* Store the size of extended memory in EXTENDED_MEMORY, in order to
     tell it to non-Multiboot OSes.  */
  extended_memory = mbi.mem_upper;
  
  /*
   *  The "mbi.mem_upper" variable only recognizes upper memory in the
   *  first memory region.  If there are multiple memory regions,
   *  the rest are reported to a Multiboot-compliant OS, but otherwise
   *  unused by GRUB.
   */

  addr = get_code_end ();
  mbi.mmap_addr = addr;
  mbi.mmap_length = 0;
  cont = 0;

  do
    {
      cont = get_mmap_entry ((void *) addr, cont);

      /* If the returned buffer's length is zero, quit. */
      if (! *((unsigned long *) addr))
	break;

      mbi.mmap_length += *((unsigned long *) addr) + 4;
      addr += *((unsigned long *) addr) + 4;
    }
  while (cont);

  if (mbi.mmap_length)
    {
      unsigned long long max_addr;
      
      /*
       *  This is to get the lower memory, and upper memory (up to the
       *  first memory hole), into the "mbi.mem_{lower,upper}"
       *  elements.  This is for OS's that don't care about the memory
       *  map, but might care about total RAM available.
       */
      mbi.mem_lower = mmap_avail_at (0) >> 10;
      mbi.mem_upper = mmap_avail_at (0x100000) >> 10;

      /* Find the maximum available address. Ignore any memory holes.  */
      for (max_addr = 0, addr = mbi.mmap_addr;
	   addr < mbi.mmap_addr + mbi.mmap_length;
	   addr += *((unsigned long *) addr) + 4)
	{
	  struct AddrRangeDesc *desc = (struct AddrRangeDesc *) addr;
	  
	  if (desc->Type == MB_ARD_MEMORY && desc->Length > 0
	      && desc->BaseAddr + desc->Length > max_addr)
	    max_addr = desc->BaseAddr + desc->Length;
	}

      extended_memory = (max_addr - 0x100000) >> 10;
    }
  else if ((memtmp = get_eisamemsize ()) != -1)
    {
      cont = memtmp & ~0xFFFF;
      memtmp = memtmp & 0xFFFF;

      if (cont != 0)
	extended_memory = (cont >> 10) + 0x3c00;
      else
	extended_memory = memtmp;
      
      if (!cont || (memtmp == 0x3c00))
	memtmp += (cont >> 10);
      else
	{
	  /* XXX should I do this at all ??? */

	  mbi.mmap_addr = (unsigned long) fakemap;
	  mbi.mmap_length = sizeof (fakemap);
	  fakemap[0].Length = (mbi.mem_lower << 10);
	  fakemap[1].Length = (memtmp << 10);
	  fakemap[2].Length = cont;
	}

      mbi.mem_upper = memtmp;
    }

  saved_mem_upper = mbi.mem_upper;

  /* Get the drive info.  */
  /* FIXME: This should be postponed until a Multiboot kernel actually
     requires it, because this could slow down the start-up
     unreasonably.  */
  mbi.drives_length = 0;
  mbi.drives_addr = addr;

  /* For now, GRUB doesn't probe floppies, since it is trivial to map
     floppy drives to BIOS drives.  */
  for (drive = 0x80; drive < 0x88; drive++)
    {
      struct geometry geom;
      struct drive_info *info = (struct drive_info *) addr;
      unsigned short *port;
      
      /* Get the geometry. This ensures that the drive is present.  */
      if (get_diskinfo (drive, &geom))
	break;
      
      /* Clean out the I/O map.  */
      grub_memset ((char *) io_map, 0,
		   IO_MAP_SIZE * sizeof (unsigned short));

      /* Disable to probe I/O ports temporarily, because this doesn't
	 work with some BIOSes (maybe they are too buggy).  */
#if 0
      /* Track the int13 handler.  */
      track_int13 (drive);
#endif

      /* Set the information.  */
      info->drive_number = drive;
      info->drive_mode = ((geom.flags & BIOSDISK_FLAG_LBA_EXTENSION)
			  ? MB_DI_LBA_MODE : MB_DI_CHS_MODE);
      info->drive_cylinders = geom.cylinders;
      info->drive_heads = geom.heads;
      info->drive_sectors = geom.sectors;

      addr += sizeof (struct drive_info);
      for (port = io_map; *port; port++, addr += sizeof (unsigned short))
	*((unsigned short *) addr) = *port;

      info->size = addr - (unsigned long) info;
      mbi.drives_length += info->size;
    }

  /* Get the ROM configuration table by INT 15, AH=C0h.  */
  mbi.config_table = get_rom_config_table ();

  /* Set the boot loader name.  */
  mbi.boot_loader_name = (unsigned long) "GNU GRUB " VERSION;

  /* Get the APM BIOS table.  */
  get_apm_info ();
  if (apm_bios_info.version)
    mbi.apm_table = (unsigned long) &apm_bios_info;
  
  /*
   *  Initialize other Multiboot Info flags.
   */

  mbi.flags = (MB_INFO_MEMORY | MB_INFO_CMDLINE | MB_INFO_BOOTDEV
	       | MB_INFO_DRIVE_INFO | MB_INFO_CONFIG_TABLE
	       | MB_INFO_BOOT_LOADER_NAME);
  
  if (apm_bios_info.version)
    mbi.flags |= MB_INFO_APM_TABLE;

#endif /* STAGE1_5 */

  /* Set boot drive and partition.  */
  saved_drive = boot_drive;
  saved_partition = install_partition;

  /* Set cdrom drive.  */
  {
    struct geometry geom;
    
    /* Get the geometry.  */
    if (get_diskinfo (boot_drive, &geom)
	|| ! (geom.flags & BIOSDISK_FLAG_CDROM))
      cdrom_drive = GRUB_INVALID_DRIVE;
    else
      cdrom_drive = boot_drive;
  }
  
  /* Start main routine here.  */
  cmain ();
}