startup.s

grub 1.95 linux 的bootloader 源代码

/* startup.S - bootstrap GRUB itself */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2006  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 <config.h>
#include <grub/symbol.h>
#include <grub/boot.h>

        .file   "startup.S"
        .text
        .globl  start, _start
start:
_start:
	jmp codestart

        /*
         *  Compatibility version number
         *
         *  These MUST be at byte offset 6 and 7 of the executable
         *  DO NOT MOVE !!!
         */
        . = EXT_C(start) + 0x6
        .byte   GRUB_BOOT_VERSION_MAJOR, GRUB_BOOT_VERSION_MINOR

        /*
         *  This is a special data area 8 bytes from the beginning.
         */

        . = EXT_C(start) + 0x8

VARIABLE(grub_prefix)
        .string "/boot/grub"

        /*
         *  Leave some breathing room for the prefix.
         */

        . = EXT_C(start) + 0x50

codestart:
	/*
	 *  EFI_SYSTEM_TABLE * and EFI_HANDLE are passed on the stack.
	 */
	movl	4(%esp), %eax
	movl	%eax, EXT_C(grub_efi_image_handle)
	movl	8(%esp), %eax
	movl	%eax, EXT_C(grub_efi_system_table)
	call	EXT_C(grub_main)
	ret