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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"
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 */
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