1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
|
/* $NetBSD: fdbootblk.c,v 1.6 1994/10/27 04:21:53 cgd Exp $ */
/*-
* 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.
*
* @(#)fdbootblk.c 7.2 (Berkeley) 5/4/91
*/
/*
* 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 "
.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
movb $0xbf,%al # enable floppy interrupt, mask out rest
outb %al,$0x21
NOP
8:
movb %bl,readcmd+4
movl %edi,%ecx
/* Set read/write bytes */
xorl %edx,%edx
movb $0x0c,%dl # outb(0xC,junk); outb(0xB,0x46);
outb %al,%dx # reset DMA controller first/last flip-flop
NOP
decb %dx
movb $0x46,%al # single mode, write mem, chan 2
outb %al,%dx # output DMA controller mode byte
/* 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 */
|
