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