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7f3c30c6 WJ |
1 | /*- |
2 | * Copyright (c) 1990 The Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * This code is derived from software contributed to Berkeley by | |
6 | * William Jolitz. | |
7 | * | |
8 | * Redistribution and use in source and binary forms, with or without | |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * 1. Redistributions of source code must retain the above copyright | |
12 | * notice, this list of conditions and the following disclaimer. | |
13 | * 2. Redistributions in binary form must reproduce the above copyright | |
14 | * notice, this list of conditions and the following disclaimer in the | |
15 | * documentation and/or other materials provided with the distribution. | |
16 | * 3. All advertising materials mentioning features or use of this software | |
17 | * must display the following acknowledgement: | |
18 | * This product includes software developed by the University of | |
19 | * California, Berkeley and its contributors. | |
20 | * 4. Neither the name of the University nor the names of its contributors | |
21 | * may be used to endorse or promote products derived from this software | |
22 | * without specific prior written permission. | |
23 | * | |
24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | * SUCH DAMAGE. | |
35 | * | |
36 | * @(#)wdbootblk.c 7.1 (Berkeley) 4/28/91 | |
37 | */ | |
38 | ||
39 | /* | |
40 | * wdbootblk.s: | |
41 | * Written 7/6/90 by William F. Jolitz | |
42 | * Initial block boot for AT/386 with typical Western Digital | |
43 | * WD 1002-WA2 (or upwards compatable). Works either as | |
44 | * first and sole partition bootstrap, or as loaded by a | |
45 | * earlier BIOS boot when on an inner partition of the disk. | |
46 | * | |
47 | * Goal is to read in sucessive 7.5Kbytes of bootstrap to | |
48 | * execute. | |
49 | * | |
50 | * No attempt is made to handle disk errors. | |
51 | */ | |
52 | #include "i386/isa/isa.h" | |
53 | #include "i386/isa/wdreg.h" | |
54 | #define NOP jmp 1f ; nop ; 1: | |
55 | #define BIOSRELOC 0x7c00 | |
56 | #define start 0x70400 | |
57 | ||
58 | /* step 0 force descriptors to bottom of address space */ | |
59 | ||
60 | .byte 0xfa,0xb8,0x30,0x00,0x8e,0xd0,0xbc,0x00,0x01 #ll fb | |
61 | ||
62 | xorl %eax,%eax | |
63 | movl %ax,%ds | |
64 | movl %ax,%es | |
65 | ||
66 | /* step 1 load new descriptor table */ | |
67 | ||
68 | .byte 0x2E,0x0F,1,0x16 | |
69 | .word BIOSRELOC+0x4a #GDTptr | |
70 | # word aword cs lgdt GDTptr | |
71 | ||
72 | /* step 2 turn on protected mode */ | |
73 | ||
74 | smsw %ax | |
75 | orb $1,%al | |
76 | lmsw %ax | |
77 | jmp 1f | |
78 | nop | |
79 | ||
80 | /* step 3 reload segment descriptors */ | |
81 | ||
82 | 1: | |
83 | xorl %eax,%eax | |
84 | movb $0x10,%al | |
85 | movl %ax,%ds | |
86 | movl %ax,%es | |
87 | movl %ax,%ss | |
88 | word | |
89 | ljmp $0x8,$ BIOSRELOC+0x50 /* would be nice if .-RELOC+0x7c00 worked */ | |
90 | ||
91 | /* Global Descriptor Table contains three descriptors: | |
92 | * 0x00: Null: not used | |
93 | * 0x08: Code: code segment starts at 0 and extents for 4 gigabytes | |
94 | * 0x10: Data: data segment starts at 0 and extends for 4 gigabytes | |
95 | * (overlays code) | |
96 | */ | |
97 | GDT: | |
98 | NullDesc: .word 0,0,0,0 # null descriptor - not used | |
99 | CodeDesc: .word 0xFFFF # limit at maximum: (bits 15:0) | |
100 | .byte 0,0,0 # base at 0: (bits 23:0) | |
101 | .byte 0x9f # present/priv level 0/code/conforming/readable | |
102 | .byte 0xcf # page granular/default 32-bit/limit(bits 19:16) | |
103 | .byte 0 # base at 0: (bits 31:24) | |
104 | DataDesc: .word 0xFFFF # limit at maximum: (bits 15:0) | |
105 | .byte 0,0,0 # base at 0: (bits 23:0) | |
106 | .byte 0x93 # present/priv level 0/data/expand-up/writeable | |
107 | .byte 0xcf # page granular/default 32-bit/limit(bits 19:16) | |
108 | .byte 0 # base at 0: (bits 31:24) | |
109 | ||
110 | /* Global Descriptor Table pointer | |
111 | * contains 6-byte pointer information for LGDT | |
112 | */ | |
113 | GDTptr: .word 0x17 # limit to three 8 byte selectors(null,code,data) | |
114 | .long BIOSRELOC+0x32 # GDT -- arrgh, gas again! | |
115 | ||
116 | /* step 4 relocate to final bootstrap address. */ | |
117 | reloc: | |
118 | movl $ BIOSRELOC,%esi | |
119 | movl $ RELOC,%edi | |
120 | movl $512,%ecx | |
121 | rep | |
122 | movsb | |
123 | movl $0x60000,%esp | |
124 | pushl $dodisk | |
125 | ret | |
126 | ||
127 | /* step 5 load remaining 15 sectors off disk */ | |
128 | dodisk: | |
129 | movl $ IO_WD1+wd_seccnt,%edx | |
130 | movb $ 15,%al | |
131 | outb %al,%dx | |
132 | NOP | |
133 | movl $ IO_WD1+wd_sector,%edx | |
134 | movb $ 2,%al | |
135 | outb %al,%dx | |
136 | NOP | |
137 | #outb(wdc+wd_cyl_lo, (cyloffset & 0xff)); | |
138 | #outb(wdc+wd_cyl_hi, (cyloffset >> 8)); | |
139 | #outb(wdc+wd_sdh, WDSD_IBM | (unit << 4)); | |
140 | ||
141 | movl $ IO_WD1+wd_command,%edx | |
142 | movb $ WDCC_READ,%al | |
143 | outb %al,%dx | |
144 | NOP | |
145 | cld | |
146 | ||
147 | /* check to make sure controller is not busy and we have data ready */ | |
148 | readblk: | |
149 | movl $ IO_WD1+wd_status,%edx | |
150 | inb %dx,%al | |
151 | NOP | |
152 | testb $ WDCS_BUSY,%al | |
153 | jnz readblk | |
154 | testb $ WDCS_DRQ,%al | |
155 | jz readblk | |
156 | ||
157 | /* read a block into final position in memory */ | |
158 | ||
159 | movl $ IO_WD1+wd_data,%edx | |
160 | movl $ 256,%ecx | |
161 | .byte 0x66,0xf2,0x6d # rep insw | |
162 | NOP | |
163 | ||
164 | /* need more blocks to be read in? */ | |
165 | ||
166 | cmpl $ RELOC+16*512-1,%edi | |
167 | jl readblk | |
168 | ||
169 | /* for clever bootstrap, dig out boot unit and cylinder */ | |
170 | ||
171 | movl $ IO_WD1+wd_cyl_lo,%edx | |
172 | inb %dx,%al | |
173 | NOP | |
174 | xorl %ecx,%ecx | |
175 | movb %al,%cl | |
176 | incl %edx | |
177 | inb %dx,%al /* cyl_hi */ | |
178 | NOP | |
179 | movb %al,%ch | |
180 | pushl %ecx /* cyloffset */ | |
181 | ||
182 | incl %edx | |
183 | xorl %eax,%eax | |
184 | inb %dx,%al /* sdh */ | |
185 | andb $0x10,%al /* isolate unit # bit */ | |
186 | shrb $4,%al | |
187 | pushl %eax /* unit */ | |
188 | ||
189 | /* wd controller is major device 0 */ | |
190 | xorl %eax,%eax | |
191 | pushl %eax /* bootdev */ | |
192 | ||
193 | /* sorry, no flags at this point! */ | |
194 | ||
195 | pushl $ start | |
196 | ret /* main (dev, unit, offset) */ | |
197 | ||
198 | ebootblkcode: | |
199 | ||
200 | /* remaining space usable for a disk label */ | |
201 | ||
202 | .space 510-223 /* would be nice if .space 512-2-. worked */ | |
203 | .word 0xaa55 /* signature -- used by BIOS ROM */ | |
204 | ||
205 | ebootblk: /* MUST BE EXACTLY 0x200 BIG FOR SURE */ |