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1.1 root 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: *
1.1.1.3 ! root 36: * from: @(#)wdbootblk.c 7.1 (Berkeley) 4/28/91
! 37: * wdbootblk.c,v 1.2 1993/05/22 08:02:27 cgd Exp
1.1 root 38: */
39:
40: /*
41: * wdbootblk.s:
42: * Written 7/6/90 by William F. Jolitz
43: * Initial block boot for AT/386 with typical Western Digital
44: * WD 1002-WA2 (or upwards compatable). Works either as
45: * first and sole partition bootstrap, or as loaded by a
46: * earlier BIOS boot when on an inner partition of the disk.
47: *
48: * Goal is to read in sucessive 7.5Kbytes of bootstrap to
49: * execute.
50: *
51: * No attempt is made to handle disk errors.
52: */
53: #include "i386/isa/isa.h"
54: #include "i386/isa/wdreg.h"
1.1.1.2 root 55: #define NOP inb $0x84,%al
1.1 root 56: #define BIOSRELOC 0x7c00
1.1.1.2 root 57: #define start RELOC+0x400
1.1 root 58:
59: /* step 0 force descriptors to bottom of address space */
1.1.1.2 root 60:
61: cli
62: .byte 0xb8,0x30,0x00 /* mov $0x30,%ax */
63: mov %ax, %ss
64: .byte 0xbc,0x00,0x01 /* mov $0x100,%sp */
1.1 root 65:
66: xorl %eax,%eax
67: movl %ax,%ds
68: movl %ax,%es
69:
1.1.1.2 root 70: /* obtain BIOS parameters for hard disk XXX */
71: movb $0x9f,%ah /* write to 0x9ff00 XXX */
72: movb $0xf0,%al
73: mov %ax,%es
74: xor %edi,%edi
75:
76: .byte 0xf, 0xb4, 0x36 ; .word 0x41*4 /* lfs 0x41*4, %si */
77: xorb %ch,%ch
78: movb $0x10,%cl
79: fs
80: rep
81: movsb
82:
83: .byte 0xf, 0xb4, 0x36 ; .word 0x46*4 /* lfs 0x46*4, %si */
84: xorb %ch,%ch
85: movb $0x10,%cl
86: fs
87: rep
88: movsb
89:
90: xorl %eax,%eax
91: movl %ax,%es
92:
1.1 root 93: /* step 1 load new descriptor table */
94:
1.1.1.2 root 95: .byte 0x3E,0x0F,1,0x16
96: .word BIOSRELOC+0x6e #GDTptr
1.1 root 97: # word aword cs lgdt GDTptr
98:
99: /* step 2 turn on protected mode */
100:
101: smsw %ax
102: orb $1,%al
103: lmsw %ax
104: jmp 1f
105: nop
106:
107: /* step 3 reload segment descriptors */
108:
109: 1:
110: xorl %eax,%eax
111: movb $0x10,%al
112: movl %ax,%ds
113: movl %ax,%es
114: movl %ax,%ss
115: word
1.1.1.2 root 116: ljmp $0x8,$ BIOSRELOC+0x74 /* would be nice if .-RELOC+0x7c00 worked */
1.1 root 117:
118: /* Global Descriptor Table contains three descriptors:
119: * 0x00: Null: not used
120: * 0x08: Code: code segment starts at 0 and extents for 4 gigabytes
121: * 0x10: Data: data segment starts at 0 and extends for 4 gigabytes
122: * (overlays code)
123: */
124: GDT:
125: NullDesc: .word 0,0,0,0 # null descriptor - not used
126: CodeDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
127: .byte 0,0,0 # base at 0: (bits 23:0)
128: .byte 0x9f # present/priv level 0/code/conforming/readable
129: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
130: .byte 0 # base at 0: (bits 31:24)
131: DataDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
132: .byte 0,0,0 # base at 0: (bits 23:0)
133: .byte 0x93 # present/priv level 0/data/expand-up/writeable
134: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
135: .byte 0 # base at 0: (bits 31:24)
136:
137: /* Global Descriptor Table pointer
138: * contains 6-byte pointer information for LGDT
139: */
140: GDTptr: .word 0x17 # limit to three 8 byte selectors(null,code,data)
1.1.1.2 root 141: .long BIOSRELOC+0x56 # GDT -- arrgh, gas again!
1.1 root 142:
143: /* step 4 relocate to final bootstrap address. */
144: reloc:
145: movl $ BIOSRELOC,%esi
146: movl $ RELOC,%edi
147: movl $512,%ecx
148: rep
149: movsb
1.1.1.2 root 150: movl $0xa0000, %esp
1.1 root 151: pushl $dodisk
152: ret
153:
154: /* step 5 load remaining 15 sectors off disk */
155: dodisk:
156: movl $ IO_WD1+wd_seccnt,%edx
157: movb $ 15,%al
158: outb %al,%dx
159: NOP
160: movl $ IO_WD1+wd_sector,%edx
161: movb $ 2,%al
162: outb %al,%dx
163: NOP
164: #outb(wdc+wd_cyl_lo, (cyloffset & 0xff));
165: #outb(wdc+wd_cyl_hi, (cyloffset >> 8));
166: #outb(wdc+wd_sdh, WDSD_IBM | (unit << 4));
167:
168: movl $ IO_WD1+wd_command,%edx
169: movb $ WDCC_READ,%al
170: outb %al,%dx
171: NOP
172: cld
173:
174: /* check to make sure controller is not busy and we have data ready */
175: readblk:
176: movl $ IO_WD1+wd_status,%edx
177: NOP
1.1.1.2 root 178: inb %dx,%al
1.1 root 179: testb $ WDCS_BUSY,%al
180: jnz readblk
181: testb $ WDCS_DRQ,%al
182: jz readblk
183:
184: /* read a block into final position in memory */
185:
186: movl $ IO_WD1+wd_data,%edx
187: movl $ 256,%ecx
188: .byte 0x66,0xf2,0x6d # rep insw
189: NOP
190:
191: /* need more blocks to be read in? */
192:
193: cmpl $ RELOC+16*512-1,%edi
194: jl readblk
195:
196: /* for clever bootstrap, dig out boot unit and cylinder */
197:
198: movl $ IO_WD1+wd_cyl_lo,%edx
199: inb %dx,%al
200: xorl %ecx,%ecx
201: movb %al,%cl
202: incl %edx
203: NOP
1.1.1.2 root 204: inb %dx,%al /* cyl_hi */
1.1 root 205: movb %al,%ch
206: pushl %ecx /* cyloffset */
207:
208: incl %edx
209: xorl %eax,%eax
1.1.1.2 root 210: NOP
1.1 root 211: inb %dx,%al /* sdh */
212: andb $0x10,%al /* isolate unit # bit */
213: shrb $4,%al
214: pushl %eax /* unit */
215:
216: /* wd controller is major device 0 */
217: xorl %eax,%eax
218: pushl %eax /* bootdev */
219:
220: /* sorry, no flags at this point! */
221:
1.1.1.2 root 222: movl $ start, %eax
223: call %eax /* main (dev, unit, offset) */
1.1 root 224:
225: ebootblkcode:
226:
227: /* remaining space usable for a disk label */
228:
1.1.1.2 root 229: .org 0x1fe
1.1 root 230: .word 0xaa55 /* signature -- used by BIOS ROM */
231:
232: ebootblk: /* MUST BE EXACTLY 0x200 BIG FOR SURE */
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