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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: *
44: * Goal is to read in sucessive 7.5Kbytes of bootstrap to
45: * execute.
46: *
47: * No attempt is made to handle disk errors.
48: */
49: /*#include "/sys/i386/isa/isa.h"
50: #include "/sys/i386/isa/fdreg.h"*/
1.1.1.3 ! root 51: #define NOP inb $0x84,%al
1.1 root 52: #define BIOSRELOC 0x7c00
1.1.1.3 ! root 53: #define start RELOC+0x400
1.1 root 54:
1.1.1.3 ! root 55: /* mumbo-jumbo to pacify DOS, in the hope of getting diskcopy to work */
! 56: jmp 1f
! 57: .asciz "386BSD "
! 58: .byte 1 # sectors per allocation
! 59: .word 15 # additional sectors for bootstrap
! 60: .word 0 # number of DOS fat sectors
! 61: .word 0 # number of DOS rootdir entries
! 62: .byte 0xf0 # media descriptor
! 63: .word 0 # number of sectors per a DOS fat entry
! 64: .word 18 # number of sectors per track
! 65: .word 2 # number of heads
! 66: .long 0 # number of hidden sectors
! 67: .long 2880-18 # logical sectors per volume
! 68: .byte 0 # physical drive
! 69: .byte 0x29 # ?
! 70: .long 137 # binary id
! 71: .ascii "Release 0.1" # volume label
! 72: .space 5
! 73: 1:
1.1 root 74: /* step 0 force descriptors to bottom of address space */
1.1.1.3 ! root 75:
! 76: cli
! 77: .byte 0xb8,0x30,0x00 /* mov $0x30,%ax */
! 78: mov %ax, %ss
! 79: .byte 0xbc,0x00,0x01 /* mov $0x100,%sp */
1.1 root 80:
81: xorl %eax,%eax
82: movl %ax,%ds
83: movl %ax,%es
84:
1.1.1.3 ! root 85: /* obtain BIOS parameters for hard disk XXX */
! 86: movb $0x9f,%ah /* write to 0x9ff00 XXX */
! 87: movb $0xf0,%al
! 88: mov %ax,%es
! 89: xor %edi,%edi
! 90:
! 91: .byte 0xf, 0xb4, 0x36 ; .word 0x41*4 /* lfs 0x41*4, %si */
! 92: xorb %ch,%ch
! 93: movb $0x10,%cl
! 94: fs
! 95: rep
! 96: movsb
! 97:
! 98: .byte 0xf, 0xb4, 0x36 ; .word 0x46*4 /* lfs 0x46*4, %si */
! 99: xorb %ch,%ch
! 100: movb $0x10,%cl
! 101: fs
! 102: rep
! 103: movsb
! 104:
! 105: xorl %eax,%eax
! 106: movl %ax,%es
! 107:
1.1 root 108: /* step 1 load new descriptor table */
109:
1.1.1.3 ! root 110: .byte 0x2E,0x0F,1,0x16 /* word aword cs lgdt GDTptr */
! 111: .word BIOSRELOC+0xa4 #GDTptr
1.1 root 112:
113: /* step 2 turn on protected mode */
114:
115: smsw %ax
116: orb $1,%al
117: lmsw %ax
118: jmp 1f
119: nop
120:
121: /* step 3 reload segment descriptors */
122:
123: 1:
124: xorl %eax,%eax
125: movb $0x10,%al
126: movl %ax,%ds
127: movl %ax,%es
128: movl %ax,%ss
129: word
1.1.1.3 ! root 130: ljmp $0x8,$ BIOSRELOC+0xb3 /* would be nice if .-RELOC+0x7c00 worked */
1.1 root 131:
132: /* Global Descriptor Table contains three descriptors:
133: * 0x00: Null: not used
134: * 0x08: Code: code segment starts at 0 and extents for 4 gigabytes
135: * 0x10: Data: data segment starts at 0 and extends for 4 gigabytes
136: * (overlays code)
137: */
138: GDT:
139: NullDesc: .word 0,0,0,0 # null descriptor - not used
140: CodeDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
141: .byte 0,0,0 # base at 0: (bits 23:0)
142: .byte 0x9f # present/priv level 0/code/conforming/readable
143: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
144: .byte 0 # base at 0: (bits 31:24)
145: DataDesc: .word 0xFFFF # limit at maximum: (bits 15:0)
146: .byte 0,0,0 # base at 0: (bits 23:0)
147: .byte 0x93 # present/priv level 0/data/expand-up/writeable
148: .byte 0xcf # page granular/default 32-bit/limit(bits 19:16)
149: .byte 0 # base at 0: (bits 31:24)
150:
151: /* Global Descriptor Table pointer
152: * contains 6-byte pointer information for LGDT
153: */
154: GDTptr: .word 0x17 # limit to three 8 byte selectors(null,code,data)
1.1.1.3 ! root 155: .long BIOSRELOC+0x8c # GDT -- arrgh, gas again!
1.1 root 156: readcmd: .byte 0xe6,0,0,0,0,2,18,0x1b,0xff
157:
158: /* step 4 relocate to final bootstrap address. */
159: reloc:
160: movl $ BIOSRELOC,%esi
161: movl $ RELOC,%edi
162: movl $512,%ecx
163: rep
164: movsb
1.1.1.3 ! root 165: movl $0xa0000, %esp
1.1 root 166: pushl $dodisk
167: ret
168:
169: /* step 5 load remaining 15 sectors off disk */
170: dodisk:
1.1.1.3 ! root 171: movl $ RELOC+0x200, %edi
! 172: xorl %ebx, %ebx
! 173: incb %bl # shl $1,%bl
1.1 root 174: incb %bl
175: movb $0x20,%al # do a eoi
176: outb %al,$0x20
177:
178: NOP
179: movb $0x07,%al
180: outb %al,$0x21
181: NOP
182: 8:
183: movb %bl,readcmd+4
184: movl %edi,%ecx
185:
186: /* Set read/write bytes */
187: xorl %edx,%edx
188: movb $0x0c,%dl # outb(0xC,0x46); outb(0xB,0x46);
189: movb $0x46,%al
190: outb %al,%dx
191: NOP
192: decb %dx
193: outb %al,%dx
194:
195: /* Send start address */
196: movb $0x04,%dl # outb(0x4, addr);
197: movb %cl,%al
198: outb %al,%dx
199: NOP
200: movb %ch,%al # outb(0x4, addr>>8);
201: outb %al,%dx
202: NOP
203: rorl $8,%ecx # outb(0x81, addr>>16);
204: movb %ch,%al
205: outb %al,$0x81
206: NOP
207:
208: /* Send count */
209: movb $0x05,%dl # outb(0x5, 0);
210: xorl %eax,%eax
211: outb %al,%dx
212: NOP
213: movb $2,%al # outb(0x5,2);
214: outb %al,%dx
215: NOP
216:
217: /* set channel 2 */
1.1.1.3 ! root 218: movb $2,%al # outb(0x0A,2);
1.1 root 219: outb %al,$0x0A
220: NOP
221:
222: /* issue read command to fdc */
223: movw $0x3f4,%dx
224: movl $readcmd,%esi
225: xorl %ecx,%ecx
226: movb $9,%cl
227:
1.1.1.3 ! root 228: 2: NOP
! 229: inb %dx,%al
1.1 root 230: testb $0x80,%al
231: jz 2b
232:
233: incb %dx
1.1.1.3 ! root 234: NOP
1.1 root 235: movl (%esi),%al
236: outb %al,%dx
237: NOP
238: incl %esi
239: decb %dx
240: loop 2b
241:
242: /* watch the icu looking for an interrupt signalling completion */
243: xorl %edx,%edx
244: movb $0x20,%dl
1.1.1.3 ! root 245: 2:
! 246: NOP
! 247: movb $0xc,%al
1.1 root 248: outb %al,%dx
249: NOP
250: inb %dx,%al
251: andb $0x7f,%al
252: cmpb $6,%al
253: jne 2b
1.1.1.3 ! root 254: NOP
1.1 root 255: movb $0x20,%al # do a eoi
256: outb %al,%dx
257: NOP
258:
259: movl $0x3f4,%edx
260: xorl %ecx,%ecx
261: movb $7,%cl
1.1.1.3 ! root 262: 2:
1.1 root 263: NOP
1.1.1.3 ! root 264: inb %dx,%al
1.1 root 265: andb $0xC0,%al
266: cmpb $0xc0,%al
267: jne 2b
268: incb %dx
269: inb %dx,%al
270: decb %dx
271: loop 2b
272:
273: /* extract the status bytes after the read. must we do this? */
274: addw $0x200,%edi # next addr to load to
275: incb %bl
1.1.1.2 root 276: cmpb $15,%bl
1.1 root 277: jle 8b
278:
279: /* for clever bootstrap, dig out boot unit and cylinder */
280: pushl $0
281: pushl $0
282:
283: /* fd controller is major device 2 */
284: pushl $2 /* dev */
285:
286: /* sorry, no flags at this point! */
287:
1.1.1.3 ! root 288: movl $ start, %eax
! 289: call %eax /* main (dev, unit, off) */
1.1 root 290:
291: ebootblkcode:
292:
293: /* remaining space usable for a disk label */
294:
1.1.1.3 ! root 295: .org 0x1fe
1.1 root 296: .word 0xaa55 /* signature -- used by BIOS ROM */
297:
298: ebootblk: /* MUST BE EXACTLY 0x200 BIG FOR SURE */
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