freebsd-skq/sys/boot/pc98/boot2/start.S
2002-05-14 12:34:03 +00:00

476 lines
10 KiB
ArmAsm

/*
* 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
* $FreeBSD$
*/
/*
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.
*/
/*
* Ported to PC-9801 by Yoshio Kimura
*/
#include "asm.h"
.file "start.S"
SIGNATURE= 0xaa55
LOADSZ= 8192 /* size of unix boot */
NAMEBLOCKMAGIC= 0xfadefeed /* value of magicnumebr for block2 */
/*
* This DEBUGMSG(msg) macro may be useful for debugging. Its use is
* restricted to this file since it only works in real mode.
*/
#define DEBUGMSG(msg) \
data32 ; \
mov $msg, %esi ; \
data32 ; \
call message
.code16
.text
.globl start
start:
jmp main
boot_cyl:
.word 0
String "IPL1 "
main:
/* set up %ds */
xor %ax, %ax
mov %ax, %ds
/* set up %ss and %esp */
mov $BOOTSEG, %eax
mov %ax, %ss
/*
* make a little room on the stack for
* us to save the default bootstring we might find..
* effectively, we push the bootstring.
*/
mov $BOOTSTACK-64, %esp
/* set up %es, (where we will load boot2 to) */
mov %ax, %es
push %es
push %ecx
push %dx
mov $0xa000, %eax
mov %ax, %es
/* set up graphic screen */
movb $0x42, %ah
movb $0xc0, %ch
int $0x18
movb $0x40, %ah
int $0x18
mov $0x0a00, %eax /* 80 x 25 mode */
int $0x18
movb $0x0c, %ah /* text on */
int $0x18
/* cursor home and on */
xor %dx, %dx
movb $0x13, %ah
int $0x18
movb $0x11, %ah
int $0x18
/* keyboad reset */
movb $0x03, %ah
int $0x18
/* transfer PC-9801 system common area to 0xa1000 */
mov $0x0000, %esi
mov $0x1000, %edi
mov $0x0630, %ecx
cld
rep
movsb
/* transfer EPSON machine type to 0xa1200 */
push %ds
mov $0xfd00, %eax
mov %ax, %ds
mov 0x804, %eax
and $0x00ffffff, %eax
mov %eax, %es: (0x1624)
pop %ds
pop %dx
pop %ecx
pop %es
/* bootstrap passes */
mov %cs, %bx
cmp $0x1fe0, %bx
jz fd
cmp $0x1fc0, %bx
jnz hd
xor %cx, %cx
movb 0x584, %al
andb $0xf0, %al
cmpb $0x30, %al
jz fd
cmpb $0x90, %al
jnz hd
fd:
mov $0x0200, %cx
mov $0x0001, %dx
movb $0xd6, %ah
jmp load
hd:
and %cx, %cx
jnz 1f
.code32
addr32
mov %cs: (boot_cyl), %ecx /* actualy %cx in real mode */
.code16
1:
xor %dx, %dx
movb $0x06, %ah
/*
* BIOS call "INT 0x1B Function 0xn6" to read sectors from disk into memory
* Call with %ah = 0xd6(for floppy disk) or 0x06(for hard disk)
* %al = DA/UA
* %bx = data length
* %ch = sector size(for floppy) or cylinder(for hard)
* %cl = cylinder
* %dh = head
* %dl = sector
* %es:%bp = segment:offset of buffer
* Return:
* %ah = 0x0 on success; err code on failure
*/
load:
#ifdef NAMEBLOCK
/*
* Load the second sector and see if it is a boot instruction block.
* If it is then scan the contents for the first valid string and copy it to
* the location of the default boot string.. then zero it out.
* Finally write the block back to disk with the zero'd out entry..
* I hate writing at this stage but we need this to be persistant.
* If the boot fails, then the next boot will get the next string.
* /etc/rc will regenerate a complete block2 iff the boot succeeds.
*
* Format of block 2 is:
* [NAMEBLOCKMAGIC] <--0xdeafc0de
* [nulls]
* [bootstring]NULL <---e.g. 0:wd(0,a)/kernel.experimental
* [bootstring]NULL <---e.g. 0:wd(0,a)/kernel.old
* ....
* [bootstring]NULL <---e.g. 0:wd(0,f)/kernel
* FF FF FF
*/
where:
/*
* save things we might smash
* (that are not smashed immedatly after us anyway.)
*/
data32
push %ecx /* preserve 'cyl,sector ' */
data32
push %edx
/*
* Load the second sector
* 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
*/
data32
movl $0x0201, %eax /function 2 (read) 1 sector */
xor %ebx, %ebx /* %bx = 0 */ /* buffer address (ES:0) */
data32
movl $0x0002, %ecx /* sector 2, cylinder 0 */
data32
andl $0x00ff, %edx /* head 0, drive N */
int $0x13
data32
jb read_error
/*
* confirm that it is one for us
*/
data32
xorl %ebx, %ebx /* magic number at start of buffer */
data32
addr32
movl %es:(%ebx), %eax
data32
cmpl $NAMEBLOCKMAGIC, %eax
data32
jne notours /* not ours so return to caller */
/*
* scan for a bootstring
* Skip the magic number, and scan till we find a non-null,
* or a -1
*/
incl %ebx /* quicker and smaller */
incl %ebx
incl %ebx
scan:
incl %ebx
addr32
movb %es:(%ebx), %al /* load the next byte */
testb %al, %al /* and if it is null */
data32 /* keep scanning (past deleted entries) */
jz scan
incb %al /* now look for -1 */
data32
jz notours /* if we reach the 0xFF then we have finished */
/*
* save our settings.. we need them twice..
*/
data32
push %ebx
/*
* copy it to the default string location
* which is just above the stack for 64 bytes.
*/
data32
movl $BOOTSTACK-64, %ecx /* 64 bytes at the top of the stack */
nxtbyte:
addr32
movb %es:(%ebx), %al /* get the next byte in */
addr32
movb %al, %es:(%ecx) /* and transfer it to the name buffer */
incl %ebx /* get on with the next byte */
incl %ecx /* get on with the next byte */
testb %al, %al /* if it was 0 then quit this */
data32
jnz nxtbyte /* and looop if more to do */
/*
* restore the saved settings and
* zero it out so next time we don't try it again
*/
data32
pop %ebx /* get back our starting location */
#ifdef NAMEBLOCK_WRITEBACK
nxtbyte2:
addr32
movb %es:(%ebx), %al /* get the byte */
addr32
movb $0, %es:(%ebx) /* zero it out */
data32
incl %ebx /* point to the next byte */
testb %al, %al /* check if we have finished.. */
data32
jne nxtbyte2
/*
* Write the second sector back
* Load the second sector
* BIOS call "INT 0x13 Function 0x3" to write sectors from memory to disk
* Call with %ah = 0x3
* %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
*/
data32
movl $0x0301, %eax /* write 1 sector */
xor %ebx, %ebx /* buffer is at offset 0 */
data32
movl $0x0002, %ecx /* block 2 */
data32
andl $0xff, %edx /* head 0 */
int $0x13
data32
jnb notours
data32
mov $eread, %esi
jmp err_stop
#endif /* NAMEBLOCK_WRITEBACK */
/*
* return to the main-line
*/
notours:
data32
pop %edx
data32
pop %ecx
#endif
mov $LOADSZ, %ebx
movb 0x584, %al
xor %bp, %bp /* %bp = 0, put it at 0 in the BOOTSEG */
int $0x1b
jc 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".
*/
.code32
data32
ljmp $BOOTSEG, $ EXT(boot2)
.code16
/*
* read_error
*/
read_error:
mov $eread, %esi
err_stop:
call message
jmp stop
/*
* message: write the error message in %ds:%esi to console
*/
message:
push %eax
push %ebx
push %ds
push %es
mov $0xe000, %dx
mov 0x501, %al
testb $0x08, %al
jnz 1f
mov $0xa000, %dx
1:
mov %dx, %es
mov %cs, %ax
mov %ax, %ds
mov vram, %di
mov $0x00e1, %bx
mov $160, %cx
cld
nextb:
lodsb /* load a byte into %al */
cmpb $0x0, %al
je done
cmpb $0x0d, %al
je cr_code
cmpb $0x0a, %al
je lf_code
movb %bl, %es:0x2000(%di)
stosb
inc %di
jmp move_cursor
lf_code:
add %cx, %di
jmp move_cursor
cr_code:
xor %dx, %dx
mov %di, %ax
div %cx
sub %dx, %di
move_cursor:
mov %di, %dx
movb $0x13, %ah
int $0x18
jmp nextb
done:
mov %di, vram
pop %es
pop %ds
pop %ebx
pop %eax
ret
stop: hlt
jmp stop /* halt doesnt actually halt forever */
vram:
.word 0
/* error messages */
#ifdef DEBUG
one: String "1-\0"
two: String "2-\0"
three: String "3-\0"
four: String "4-\0"
#endif /* DEBUG */
#ifdef NAMEBLOCK_WRITEBACK
ewrite: String "Write error\r\n\0"
#endif /* NAMEBLOCK_WRITEBACK */
eread: String "Read error\r\n\0"
enoboot: String "No bootable partition\r\n\0"
endofcode:
. = EXT(start) + 0x1be
/* Partition table */
.fill 0x30,0x1,0x0
.byte 0x80, 0x00, 0x01, 0x00
.byte 0xa5, 0xff, 0xff, 0xff
.byte 0x00, 0x00, 0x00, 0x00
.byte 0x50, 0xc3, 0x00, 0x00
/* the last 2 bytes in the sector 0 contain the signature */
.value SIGNATURE
ENTRY(disklabel)
. = EXT(start) + 0x400