NetBSD/sys/arch/i386/stand/fdbootblk.c

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1993-03-21 12:45:37 +03:00
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)fdbootblk.c 7.2 (Berkeley) 5/4/91
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* $Id: fdbootblk.c,v 1.5 1993/08/02 18:17:39 mycroft Exp $
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*/
/*
* fdbootblk.s:
* Written 10/6/90 by William F. Jolitz
* Initial block boot for AT/386 with typical stupid NEC controller
*
* Goal is to read in sucessive 7.5Kbytes of bootstrap to
* execute.
*
* No attempt is made to handle disk errors.
*/
/*#include "/sys/i386/isa/isa.h"
#include "/sys/i386/isa/fdreg.h"*/
#define NOP inb $0x84,%al
#define BIOSRELOC 0x7c00
#define start RELOC+0x400
/* mumbo-jumbo to pacify DOS, in the hope of getting diskcopy to work */
jmp 1f
.asciz "NetBSD "
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.byte 1 # sectors per allocation
.word 15 # additional sectors for bootstrap
.word 0 # number of DOS fat sectors
.word 0 # number of DOS rootdir entries
.byte 0xf0 # media descriptor
.word 0 # number of sectors per a DOS fat entry
.word 18 # number of sectors per track
.word 2 # number of heads
.long 0 # number of hidden sectors
.long 2880-18 # logical sectors per volume
.byte 0 # physical drive
.byte 0x29 # ?
.long 137 # binary id
.ascii "Release 0.1" # volume label
.space 5
1:
/* step 0 force descriptors to bottom of address space */
cli
.byte 0xb8,0x30,0x00 /* mov $0x30,%ax */
mov %ax, %ss
.byte 0xbc,0x00,0x01 /* mov $0x100,%sp */
xorl %eax,%eax
movl %ax,%ds
movl %ax,%es
/* obtain BIOS parameters for hard disk XXX */
movb $0x9f,%ah /* write to 0x9ff00 XXX */
movb $0xf0,%al
mov %ax,%es
xor %edi,%edi
.byte 0xf, 0xb4, 0x36 ; .word 0x41*4 /* lfs 0x41*4, %si */
xorb %ch,%ch
movb $0x10,%cl
fs
rep
movsb
.byte 0xf, 0xb4, 0x36 ; .word 0x46*4 /* lfs 0x46*4, %si */
xorb %ch,%ch
movb $0x10,%cl
fs
rep
movsb
xorl %eax,%eax
movl %ax,%es
/* step 1 load new descriptor table */
.byte 0x2E,0x0F,1,0x16 /* word aword cs lgdt GDTptr */
.word BIOSRELOC+0xa4 #GDTptr
/* step 2 turn on protected mode */
smsw %ax
orb $1,%al
lmsw %ax
jmp 1f
nop
/* step 3 reload segment descriptors */
1:
xorl %eax,%eax
movb $0x10,%al
movl %ax,%ds
movl %ax,%es
movl %ax,%ss
word
ljmp $0x8,$ BIOSRELOC+0xb3 /* would be nice if .-RELOC+0x7c00 worked */
/* Global Descriptor Table contains three descriptors:
* 0x00: Null: not used
* 0x08: Code: code segment starts at 0 and extents for 4 gigabytes
* 0x10: Data: data segment starts at 0 and extends for 4 gigabytes
* (overlays code)
*/
GDT:
NullDesc: .word 0,0,0,0 # null descriptor - not used
CodeDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
.byte 0,0,0 # base at 0: (bits 23:0)
.byte 0x9f # present/priv level 0/code/conforming/readable
.byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
.byte 0 # base at 0: (bits 31:24)
DataDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
.byte 0,0,0 # base at 0: (bits 23:0)
.byte 0x93 # present/priv level 0/data/expand-up/writeable
.byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
.byte 0 # base at 0: (bits 31:24)
/* Global Descriptor Table pointer
* contains 6-byte pointer information for LGDT
*/
GDTptr: .word 0x17 # limit to three 8 byte selectors(null,code,data)
.long BIOSRELOC+0x8c # GDT -- arrgh, gas again!
readcmd: .byte 0xe6,0,0,0,0,2,18,0x1b,0xff
/* step 4 relocate to final bootstrap address. */
reloc:
movl $ BIOSRELOC,%esi
movl $ RELOC,%edi
movl $512,%ecx
rep
movsb
movl $0xa0000, %esp
pushl $dodisk
ret
/* step 5 load remaining 15 sectors off disk */
dodisk:
movl $ RELOC+0x200, %edi
xorl %ebx, %ebx
incb %bl # shl $1,%bl
incb %bl
movb $0x20,%al # do a eoi
outb %al,$0x20
NOP
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movb $0xbf,%al # enable floppy interrupt, mask out rest
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outb %al,$0x21
NOP
8:
movb %bl,readcmd+4
movl %edi,%ecx
/* Set read/write bytes */
xorl %edx,%edx
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movb $0x0c,%dl # outb(0xC,junk); outb(0xB,0x46);
outb %al,%dx # reset DMA controller first/last flip-flop
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NOP
decb %dx
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movb $0x46,%al # single mode, write mem, chan 2
outb %al,%dx # output DMA controller mode byte
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/* Send start address */
movb $0x04,%dl # outb(0x4, addr);
movb %cl,%al
outb %al,%dx
NOP
movb %ch,%al # outb(0x4, addr>>8);
outb %al,%dx
NOP
rorl $8,%ecx # outb(0x81, addr>>16);
movb %ch,%al
outb %al,$0x81
NOP
/* Send count */
movb $0x05,%dl # outb(0x5, 0);
xorl %eax,%eax
outb %al,%dx
NOP
movb $2,%al # outb(0x5,2);
outb %al,%dx
NOP
/* set channel 2 */
movb $2,%al # outb(0x0A,2);
outb %al,$0x0A
NOP
/* issue read command to fdc */
movw $0x3f4,%dx
movl $readcmd,%esi
xorl %ecx,%ecx
movb $9,%cl
2: NOP
inb %dx,%al
testb $0x80,%al
jz 2b
incb %dx
NOP
movl (%esi),%al
outb %al,%dx
NOP
incl %esi
decb %dx
loop 2b
/* watch the icu looking for an interrupt signalling completion */
xorl %edx,%edx
movb $0x20,%dl
2:
NOP
movb $0xc,%al
outb %al,%dx
NOP
inb %dx,%al
andb $0x7f,%al
cmpb $6,%al
jne 2b
NOP
movb $0x20,%al # do a eoi
outb %al,%dx
NOP
movl $0x3f4,%edx
xorl %ecx,%ecx
movb $7,%cl
2:
NOP
inb %dx,%al
andb $0xC0,%al
cmpb $0xc0,%al
jne 2b
incb %dx
inb %dx,%al
decb %dx
loop 2b
/* extract the status bytes after the read. must we do this? */
addw $0x200,%edi # next addr to load to
incb %bl
cmpb $15,%bl
jle 8b
/* for clever bootstrap, dig out boot unit and cylinder */
pushl $0
pushl $0
/* fd controller is major device 2 */
pushl $2 /* dev */
/* sorry, no flags at this point! */
movl $ start, %eax
call %eax /* main (dev, unit, off) */
ebootblkcode:
/* remaining space usable for a disk label */
.org 0x1fe
.word 0xaa55 /* signature -- used by BIOS ROM */
ebootblk: /* MUST BE EXACTLY 0x200 BIG FOR SURE */