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|
/* $NetBSD: start.S,v 1.12 1995/01/18 17:34:18 mycroft Exp $ */
/*
* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
*
* 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.
*/
/*
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 <machine/asm.h>
#define addr32 .byte 0x67
#define data32 .byte 0x66
#define BOOTSEG 0x0100 /* boot will be loaded here (below 640K) */
#define BOOTSTACK 0xfffc /* boot stack */
#define SIGNATURE 0xaa55 /* MBR signature */
#define LOADSZ 15 /* size of unix boot */
#define PARTSTART 0x1be /* starting address of partition table */
#define NUMPART 4 /* number of partitions in partition table */
#define PARTSZ 16 /* each partition table entry is 16 bytes */
#define BSDPART 0xA6 /* OpenBSD partition identification */
#define OLDBSDPART 0xA5 /* 386/Net/FreeBSD partition identification */
#define BOOTABLE 0x80 /* value of boot_ind, means bootable partition */
.text
.globl start
ENTRY(boot1)
start:
#ifndef DOSREAD
# start (aka boot1) is loaded at 0x0:0x7c00 but we want 0x7c0:0
# ljmp to the next instruction to adjust %cs
data32
ljmp $0x7c0, $start1
start1:
# set up %ds
movl %cs, %ax
movl %ax, %ds
# set up %ss and %esp
data32
movl $BOOTSEG, %eax
movl %ax, %ss
data32
movl $BOOTSTACK, %esp
/*** set up %es, (where we will load boot2 to) ***/
movl %ax, %es
#ifdef SERIAL
# Initialize the serial port to 9600 baud, 8N1.
data32
pushl %edx
data32
movl $0x00e3, %eax
xorl %edx, %edx
int $0x14
data32
popl %edx
#endif
#ifdef DEBUG
data32
movl $one, %esi
data32
call message
#endif
# bootstrap passes us drive number in %dl
cmpb $0x80, %dl
data32
jae hd
fd:
# reset the disk system
#ifdef DEBUG
data32
movl $two, %esi
data32
call message
#endif
movb $0x00, %ah
int $0x13
#ifdef DEBUG
data32
movl $three, %esi
data32
call message
#endif
data32
movl $0x0001, %ecx # cyl 0, sector 1
movb $0x00, %dh # head
# XXX Override the drive number.
movb $0x00, %dl
data32
jmp load
hd: /**** load sector 0 into the BOOTSEG ****/
#ifdef DEBUG
data32
movl $four, %esi
data32
call message
#endif
data32
movl $0x0201, %eax
xorl %ebx, %ebx # %bx = 0
data32
movl $0x0001, %ecx
#ifdef DEBUG
data32
movl $five, %esi
data32
call message
#endif
data32
andl $0xff, %edx
/*mov $0x0080, %edx*/
int $0x13
data32
jb read_error
/***# find the first OpenBSD partition *****/
data32
movl $PARTSTART, %ebx
data32
movl $NUMPART, %ecx
again:
addr32
movb %es:4(%ebx), %al
cmpb $BSDPART, %al
data32
je found
data32
addl $PARTSZ, %ebx
data32
loop again
/***# find the first 386/Net/FreeBSD partition *****/
data32
movl $PARTSTART, %ebx
data32
movl $NUMPART, %ecx
again2:
addr32
movb %es:4(%ebx), %al
cmpb $OLDBSDPART, %al
data32
je found
data32
addl $PARTSZ, %ebx
data32
loop again2
data32
movl $enoboot, %esi
data32
jmp err_stop
#else /* !DOSREAD */
movb $0xff, %dl
jmp _C_LABEL(boot2)
#endif /* DOSREAD */
#ifndef DOSREAD
/*
# 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 */
xorl %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
movl $six, %esi
data32
call message
#endif
data32
ljmp $BOOTSEG, $_C_LABEL(boot2)
#
# read_error
#
read_error:
data32
movl $eread, %esi
err_stop:
data32
call message
data32
jmp stop
#
# message: write the error message in %ds:%esi to console
#
message:
/*
#ifndef SERIAL
# BIOS call "INT 10H Function 0Eh" to write character to console
# Call with %ah = 0x0e
# %al = character
# %bh = page
# %bl = foreground color
#else
# BIOS call "INT 14H Function 01h" to write character to console
# Call with %ah = 0x01
# %al = character
# %dx = port number
#endif
*/
data32
pushl %eax
data32
pushl %ebx
data32
pushl %edx
#endif
nextb:
cld
lodsb # load a byte into %al
testb %al, %al
data32
jz done
#ifndef SERIAL
movb $0x0e, %ah
data32
movl $0x0001, %ebx
int $0x10
#else
movb $0x01, %ah
xorl %edx, %edx
int $0x14
#endif
data32
jmp nextb
done:
data32
popl %edx
data32
popl %ebx
data32
popl %eax
data32
ret
/* Conventional GDT indexes. */
#define BOOT_CS_INDEX 3
#define BOOT_CS16_INDEX 5
#define BOOT_DS_INDEX 4
ENTRY(boot2)
data32
xorl %eax, %eax
movl %cs, %ax
movl %ax, %ds
movl %ax, %es
addr32
data32
movl %eax, _C_LABEL(ourseg)
data32
shll $4, %eax
/* fix up GDT entries for bootstrap */
#define FIXUP(gdt_index) \
addr32; \
movl %eax, _C_LABEL(Gdt)+(8*gdt_index)+2; /* actually movw %ax */ \
addr32; \
movb %bl, _C_LABEL(Gdt)+(8*gdt_index)+4
data32
shldl $16, %eax, %ebx
FIXUP(BOOT_CS_INDEX)
FIXUP(BOOT_CS16_INDEX)
FIXUP(BOOT_DS_INDEX)
/* fix up GDT pointer */
data32
addl $_C_LABEL(Gdt), %eax
addr32
data32
movl %eax, _C_LABEL(Gdtr)+2
/* change to protected mode */
data32
call _C_LABEL(real_to_prot)
/* clear the bss */
movl $_C_LABEL(edata), %edi
movl $_C_LABEL(end), %ecx
subl %edi, %ecx
subb %al, %al
rep
stosb
movzbl %dl, %edx /* discard head (%dh) and random high bits */
pushl %edx
call _C_LABEL(boot)
stop:
cli
hlt
/* error messages */
#ifdef DEBUG
one: .asciz "1\r\n"
two: .asciz "2\r\n"
three: .asciz "3\r\n"
four: .asciz "4\r\n"
five: .asciz "5\r\n"
six: .asciz "6\r\n"
seven: .asciz "7\r\n"
#endif DEBUG
eread: .asciz "Read error\r\n"
enoboot: .asciz "No bootable partition\r\n"
endofcode:
/* throw in a partition in case we are block0 as well */
/* flag, head, sec, cyl, typ, ehead, esect, ecyl, start, len */
. = _C_LABEL(boot1) + PARTSTART
startoflabel:
.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 */
. = _C_LABEL(boot1) + 0x1fe
.short SIGNATURE
. = _C_LABEL(boot1) + 0x200
.globl _disklabel
_disklabel:
. = _C_LABEL(boot1) + 0x400
|
