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/*
* Mach Operating System
* Copyright (c) 1992, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*
* from: Mach, Revision 2.2 92/04/04 11:36:29 rpd
* $Id: start.S,v 1.4 1994/10/02 05:18:26 rgrimes Exp $
*/
/*
Copyright 1988, 1989, 1990, 1991, 1992
by Intel Corporation, Santa Clara, California.
All Rights Reserved
Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appears in all
copies and that both the copyright notice and this permission notice
appear in supporting documentation, and that the name of Intel
not be used in advertising or publicity pertaining to distribution
of the software without specific, written prior permission.
INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "asm.h"
.file "start.s"
SIGNATURE= 0xaa55
LOADSZ= 15 /* size of unix boot */
PARTSTART= 0x1be /* starting address of partition table */
NUMPART= 4 /* number of partitions in partition table */
PARTSZ= 16 /* each partition table entry is 16 bytes */
BSDPART= 0xA5 /* value of boot_ind, means bootable partition */
BOOTABLE= 0x80 /* value of boot_ind, means bootable partition */
.text
ENTRY(boot1)
/*
* start (aka boot1) is loaded at 0x0:0x7c00 but we want 0x7c0:0
* ljmp to the next instruction to adjust %cs
*/
data32
ljmp $0x7c0, $start
start:
/* set up %ds */
mov %cs, %ax
mov %ax, %ds
/* set up %ss and %esp */
data32
mov $BOOTSEG, %eax
mov %ax, %ss
data32
mov $BOOTSTACK, %esp
/* set up %es, (where we will load boot2 to) */
mov %ax, %es
#ifdef DEBUG
data32
mov $one, %esi
data32
call message
#endif
/* bootstrap passes us drive number in %dl */
cmpb $0x80, %dl
data32
jae hd
fd:
mov $0x0, %dl
/* reset the disk system */
#ifdef DEBUG
data32
mov $two, %esi
data32
call message
#endif
movb $0x0, %ah
int $0x13
data32
mov $0x0001, %ecx /* cyl 0, sector 1 */
movb $0, %dh /* head */
#ifdef DEBUG
data32
mov $three, %esi
data32
call message
#endif
data32
jmp load
hd: /**** load sector 0 into the BOOTSEG ****/
#ifdef DEBUG
data32
mov $four, %esi
data32
call message
#endif
data32
mov $0x0201, %eax
xor %ebx, %ebx /* %bx = 0 */
data32
mov $0x0001, %ecx
#ifdef DEBUG
data32
mov $five, %esi
data32
call message
#endif
data32
andl $0xff, %edx
/*mov $0x0080, %edx*/
int $0x13
data32
jb read_error
/* find the first 386BSD partition */
data32
mov $PARTSTART, %ebx
data32
mov $NUMPART, %ecx
again:
addr32
movb %es:4(%ebx), %al
cmpb $BSDPART, %al
data32
je found
data32
add $PARTSZ, %ebx
data32
loop again
data32
mov $enoboot, %esi
data32
jmp err_stop
/*
* BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
* Call with %ah = 0x2
* %al = number of sectors
* %ch = cylinder
* %cl = sector
* %dh = head
* %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
* %es:%bx = segment:offset of buffer
* Return:
* %al = 0x0 on success; err code on failure
*/
found:
addr32
movb %es:1(%ebx), %dh /* head */
addr32
movl %es:2(%ebx), %ecx /*sect, cyl (+ 2 bytes junk in top word) */
load:
movb $0x2, %ah /* function 2 */
movb $LOADSZ, %al /* number of blocks */
xor %ebx, %ebx /* %bx = 0, put it at 0 in the BOOTSEG */
int $0x13
data32
jb read_error
/*
* ljmp to the second stage boot loader (boot2).
* After ljmp, %cs is BOOTSEG and boot1 (512 bytes) will be used
* as an internal buffer "intbuf".
*/
#ifdef DEBUG
data32
mov $six, %esi
data32
call message
#endif
data32
ljmp $BOOTSEG, $ EXT(boot2)
/*
* read_error
*/
read_error:
data32
mov $eread, %esi
err_stop:
data32
call message
data32
jmp stop
/*
* message: write the error message in %ds:%esi to console
*/
message:
/*
* Use BIOS "int 10H Function 0Eh" to write character in teletype mode
* %ah = 0xe %al = character
* %bh = page %bl = foreground color (graphics modes)
*/
data32
push %eax
data32
push %ebx
data32
mov $0x0001, %ebx
cld
nextb:
lodsb /* load a byte into %al */
cmpb $0x0, %al
data32
je done
movb $0xe, %ah
int $0x10 /* display a byte */
data32
jmp nextb
done:
data32
pop %ebx
data32
pop %eax
data32
ret
stop: hlt
data32
jmp stop /* halt doesnt actually halt forever */
/* error messages */
#ifdef DEBUG
one: String "1\r\n\0"
two: String "2\r\n\0"
three: String "3\r\n\0"
four: String "4\r\n\0"
five: String "5\r\n\0"
six: String "6\r\n\0"
seven: String "7\r\n\0"
#endif DEBUG
eread: String "Read error\r\n\0"
enoboot: String "No bootable partition\r\n\0"
endofcode:
/* throw in a partition in case we are block0 as well */
/* flag, head, sec, cyl, typ, ehead, esect, ecyl, start, len */
. = EXT(boot1) + PARTSTART
.byte 0x0,0,0,0,0,0,0,0
.long 0,0
.byte 0x0,0,0,0,0,0,0,0
.long 0,0
.byte 0x0,0,0,0,0,0,0,0
.long 0,0
.byte BOOTABLE,0,1,0,BSDPART,255,255,255
.long 0,50000
/* the last 2 bytes in the sector 0 contain the signature */
. = EXT(boot1) + 0x1fe
.value SIGNATURE
ENTRY(disklabel)
. = EXT(boot1) + 0x400
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