Attachment 661116 Details for Bug 885240 – parted mbr.s boot loader assembly code

parted mbr.s boot loader assembly code

mbr.s (text/plain), 2.07 KB, created by Steve Tyler on 2012-12-10 20:38:32 UTC

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Creator: Steve Tyler

Created: 2012-12-10 20:38:32 UTC

Size: 2.07 KB

patch

obsolete

>;   libparted - a library for manipulating disk partitions
>;   Copyright (C) 1999-2000, 2007, 2009-2012 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 3 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, see <http://www.gnu.org/licenses/>.
>
>; NOTE: I build this with:
>;	$ as86 -b /dev/stdout mbr.s | hexdump -e '8/1 "0x%02x, " "\n"'
>;
>; The build isn't done automagically by make, because as86 may not be on many
>; machines (particularly non-x86).  Also, it seems rather difficult to get
>; as86 to build object files that can be linked, especially as it's 16 bit
>; code...
>
>USE16
>
>; This code, plus the partition table is loaded into 0000:7C00 by the BIOS
>
>.text
>
>; set top of stack to 1000:B000
>
>	cli
>
>	mov	ax, #0x1000
>	mov	ss, ax
>	mov	sp, #0xB000
>
>	mov	ax, #0x0000
>	mov	ds, ax
>	mov	es, ax
>
>	sti
>
>; Copy what the BIOS loaded (i.e. the MBR + head of partition table) from
>; 0000:7c00 to 0000:0600
>
>	mov	si, #0x7c00
>	mov	di, #0x0600
>	mov	cx, #0x200
>	rep
>	movsb
>
>; Jump to the copy of the MBR
>
>	jmp	0x0000:find_boot_partition + 0x0600
>
>find_boot_partition:
>	mov	si, #0x07BE
>
>check_next_bootable:
>	cmp	[si], al
>	jnz	found_bootable
>	add	si, #0x0010
>	cmp	si, #0x07FE
>	jnz	check_next_bootable
>	jmp	error
>
>found_bootable:
>
>; Load in the boot sector at 0000:7c00
>
>	mov	ah, #2			; BIOS command (read)
>	mov	al, #1			; count
>	mov	bx, #0x7c00		; destination pointer
>	mov	dl, #0x80		; drive
>	mov	dh, byte ptr [si + 1]	; head
>	mov	cx, word ptr [si + 2]	; sector / cylinder
>	int	#0x13			; BIOS read interrupt
>
>	jmp	0x0000:0x7c00		; hand control to boot sector
>
>error:
>	jmp	error

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Attachments on bug 885240: 659598 | 659599 | 659600 | 659602 | 659695 | 659696 | 659697 | 659698 | 661116