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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: * @(#)fdbootblk.c 7.2 (Berkeley) 5/4/91
37: */
38:
39: /*
40: * fdbootblk.s:
41: * Written 10/6/90 by William F. Jolitz
42: * Initial block boot for AT/386 with typical stupid NEC controller
43: * Works only with 3.5 inch diskettes that have 16 or greater sectors/side
44: *
45: * Goal is to read in sucessive 7.5Kbytes of bootstrap to
46: * execute.
47: *
48: * No attempt is made to handle disk errors.
49: */
50: /*#include "/sys/i386/isa/isa.h"
51: #include "/sys/i386/isa/fdreg.h"*/
52: #define NOP jmp 1f ; nop ; 1:
53: #define BIOSRELOC 0x7c00
54: #define start 0x70400
55:
56: /* step 0 force descriptors to bottom of address space */
57:
58: .byte 0xfa,0xb8,0x30,0x00,0x8e,0xd0,0xbc,0x00,0x01 #ll fb
59:
60: xorl %eax,%eax
61: movl %ax,%ds
62: movl %ax,%es
63:
64: /* step 1 load new descriptor table */
65:
66: .byte 0x2E,0x0F,1,0x16
67: .word BIOSRELOC+0x4a #GDTptr
68: # word aword cs lgdt GDTptr
69:
70: /* step 2 turn on protected mode */
71:
72: smsw %ax
73: orb $1,%al
74: lmsw %ax
75: jmp 1f
76: nop
77:
78: /* step 3 reload segment descriptors */
79:
80: 1:
81: xorl %eax,%eax
82: movb $0x10,%al
83: movl %ax,%ds
84: movl %ax,%es
85: movl %ax,%ss
86: word
87: ljmp $0x8,$ BIOSRELOC+0x59 /* would be nice if .-RELOC+0x7c00 worked */
88:
89: /* Global Descriptor Table contains three descriptors:
90: * 0x00: Null: not used
91: * 0x08: Code: code segment starts at 0 and extents for 4 gigabytes
92: * 0x10: Data: data segment starts at 0 and extends for 4 gigabytes
93: * (overlays code)
94: */
95: GDT:
96: NullDesc: .word 0,0,0,0 # null descriptor - not used
97: CodeDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
98: .byte 0,0,0 # base at 0: (bits 23:0)
99: .byte 0x9f # present/priv level 0/code/conforming/readable
100: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
101: .byte 0 # base at 0: (bits 31:24)
102: DataDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
103: .byte 0,0,0 # base at 0: (bits 23:0)
104: .byte 0x93 # present/priv level 0/data/expand-up/writeable
105: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
106: .byte 0 # base at 0: (bits 31:24)
107:
108: /* Global Descriptor Table pointer
109: * contains 6-byte pointer information for LGDT
110: */
111: GDTptr: .word 0x17 # limit to three 8 byte selectors(null,code,data)
112: .long BIOSRELOC+0x32 # GDT -- arrgh, gas again!
113: readcmd: .byte 0xe6,0,0,0,0,2,18,0x1b,0xff
114:
115: /* step 4 relocate to final bootstrap address. */
116: reloc:
117: movl $ BIOSRELOC,%esi
118: movl $ RELOC,%edi
119: movl $512,%ecx
120: rep
121: movsb
122: pushl $dodisk
123: ret
124:
125: /* step 5 load remaining 15 sectors off disk */
126: dodisk:
127: movl $0x70200,%edi
128: xorl %ebx,%ebx
129: incb %bl
130: incb %bl
131: movb $0x20,%al # do a eoi
132: outb %al,$0x20
133:
134: NOP
135: movb $0x07,%al
136: outb %al,$0x21
137: NOP
138: 8:
139: movb %bl,readcmd+4
140: movl %edi,%ecx
141:
142: /* Set read/write bytes */
143: xorl %edx,%edx
144: movb $0x0c,%dl # outb(0xC,0x46); outb(0xB,0x46);
145: movb $0x46,%al
146: outb %al,%dx
147: NOP
148: decb %dx
149: outb %al,%dx
150:
151: /* Send start address */
152: movb $0x04,%dl # outb(0x4, addr);
153: movb %cl,%al
154: outb %al,%dx
155: NOP
156: movb %ch,%al # outb(0x4, addr>>8);
157: outb %al,%dx
158: NOP
159: rorl $8,%ecx # outb(0x81, addr>>16);
160: movb %ch,%al
161: outb %al,$0x81
162: NOP
163:
164: /* Send count */
165: movb $0x05,%dl # outb(0x5, 0);
166: xorl %eax,%eax
167: outb %al,%dx
168: NOP
169: movb $2,%al # outb(0x5,2);
170: outb %al,%dx
171: NOP
172:
173: /* set channel 2 */
174: # movb $2,%al # outb(0x0A,2);
175: outb %al,$0x0A
176: NOP
177:
178: /* issue read command to fdc */
179: movw $0x3f4,%dx
180: movl $readcmd,%esi
181: xorl %ecx,%ecx
182: movb $9,%cl
183:
184: 2: inb %dx,%al
185: NOP
186: testb $0x80,%al
187: jz 2b
188:
189: incb %dx
190: movl (%esi),%al
191: outb %al,%dx
192: NOP
193: incl %esi
194: decb %dx
195: loop 2b
196:
197: /* watch the icu looking for an interrupt signalling completion */
198: xorl %edx,%edx
199: movb $0x20,%dl
200: 2: movb $0xc,%al
201: outb %al,%dx
202: NOP
203: inb %dx,%al
204: NOP
205: andb $0x7f,%al
206: cmpb $6,%al
207: jne 2b
208: movb $0x20,%al # do a eoi
209: outb %al,%dx
210: NOP
211:
212: movl $0x3f4,%edx
213: xorl %ecx,%ecx
214: movb $7,%cl
215: 2: inb %dx,%al
216: NOP
217: andb $0xC0,%al
218: cmpb $0xc0,%al
219: jne 2b
220: incb %dx
221: inb %dx,%al
222: decb %dx
223: loop 2b
224:
225: /* extract the status bytes after the read. must we do this? */
226: addw $0x200,%edi # next addr to load to
227: incb %bl
1.1.1.2 ! root 228: cmpb $15,%bl
1.1 root 229: jle 8b
230:
231: /* for clever bootstrap, dig out boot unit and cylinder */
232: pushl $0
233: pushl $0
234:
235: /* fd controller is major device 2 */
236: pushl $2 /* dev */
237:
238: /* sorry, no flags at this point! */
239:
240: pushl $ start
241: ret /* main (dev, unit, off) */
242:
243: ebootblkcode:
244:
245: /* remaining space usable for a disk label */
246:
247: .space 510-310 /* would be nice if .space 512-2-. worked */
248: .word 0xaa55 /* signature -- used by BIOS ROM */
249:
250: ebootblk: /* MUST BE EXACTLY 0x200 BIG FOR SURE */
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