com32/modules/mb_header.h

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2000   Free Software Foundation, Inc.
   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
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 /*
  21  *  MultiBoot Header description
  22  */
  23
  24 struct multiboot_header
  25 {
  26   /* Must be MULTIBOOT_MAGIC - see below.  */
  27   unsigned magic;
  28
  29   /* Feature flags - see below.  */
  30   unsigned flags;
  31
  32   /*
  33    * Checksum
  34    *
  35    * The above fields plus this one must equal 0 mod 2^32.
  36    */
  37   unsigned checksum;
  38
  39   /* These are only valid if MULTIBOOT_AOUT_KLUDGE is set.  */
  40   unsigned header_addr;
  41   unsigned load_addr;
  42   unsigned load_end_addr;
  43   unsigned bss_end_addr;
  44   unsigned entry_addr;
  45
  46   /* These are only valid if MULTIBOOT_VIDEO_MODE is set.  */
  47   unsigned mode_type;
  48   unsigned width;
  49   unsigned height;
  50   unsigned depth;
  51 };
  52
  53 /*
  54  * The entire multiboot_header must be contained
  55  * within the first MULTIBOOT_SEARCH bytes of the kernel image.
  56  */
  57 #define MULTIBOOT_SEARCH                8192
  58 #define MULTIBOOT_FOUND(addr, len) \
  59   (! ((addr) & 0x3) \
  60    && (len) >= 12 \
  61    && *((int *) (addr)) == MULTIBOOT_MAGIC \
  62    && ! (*((unsigned *) (addr)) + *((unsigned *) (addr + 4)) \
  63          + *((unsigned *) (addr + 8))) \
  64    && (! (MULTIBOOT_AOUT_KLUDGE & *((int *) (addr + 4))) || (len) >= 32) \
  65    && (! (MULTIBOOT_VIDEO_MODE & *((int *) (addr + 4))) || (len) >= 48))
  66
  67 /* Magic value identifying the multiboot_header.  */
  68 #define MULTIBOOT_MAGIC                 0x1BADB002
  69
  70 /*
  71  * Features flags for 'flags'.
  72  * If a boot loader sees a flag in MULTIBOOT_MUSTKNOW set
  73  * and it doesn't understand it, it must fail.
  74  */
  75 #define MULTIBOOT_MUSTKNOW              0x0000FFFF
  76
  77 /* currently unsupported flags...  this is a kind of version number.  */
  78 #define MULTIBOOT_UNSUPPORTED           0x0000FFF8
  79
  80 /* Align all boot modules on i386 page (4KB) boundaries.  */
  81 #define MULTIBOOT_PAGE_ALIGN            0x00000001
  82
  83 /* Must pass memory information to OS.  */
  84 #define MULTIBOOT_MEMORY_INFO           0x00000002
  85
  86 /* Must pass video information to OS.  */
  87 #define MULTIBOOT_VIDEO_MODE            0x00000004
  88
  89 /* This flag indicates the use of the address fields in the header.  */
  90 #define MULTIBOOT_AOUT_KLUDGE           0x00010000