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1.1 root 1: /*
2: * Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
3: *
4: * Mach Operating System
5: * Copyright (c) 1992, 1991 Carnegie Mellon University
6: * All Rights Reserved.
7: *
8: * Permission to use, copy, modify and distribute this software and its
9: * documentation is hereby granted, provided that both the copyright
10: * notice and this permission notice appear in all copies of the
11: * software, derivative works or modified versions, and any portions
12: * thereof, and that both notices appear in supporting documentation.
13: *
14: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
15: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
16: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17: *
18: * Carnegie Mellon requests users of this software to return to
19: *
20: * Software Distribution Coordinator or [email protected]
21: * School of Computer Science
22: * Carnegie Mellon University
23: * Pittsburgh PA 15213-3890
24: *
25: * any improvements or extensions that they make and grant Carnegie Mellon
26: * the rights to redistribute these changes.
27: */
28:
29: /*
30: * HISTORY
1.1.1.2 ! root 31: * start.S,v
! 32: Revision 1.2 1993/07/11 12:02:24 andrew
! 33: Fixes from bde, including support for loading @ any MB boundary (e.g. a
! 34: kernel linked for 0xfe100000 will load at the 1MB mark) and read-ahead
! 35: buffering to speed booting from floppies. Also works with aha174x
! 36: controllers in enhanced mode.
! 37:
! 38: *
! 39: * 93/07/06 bde
! 40: * Restored BOOTSEG to 0x9000 for distribution. It should be decided
! 41: * at boot time to locate the bootstrap immediately underneath the
! 42: * debugger or whatever is in high memory. This isn't safe yet,
! 43: * because it might make the read-ahead buffer might lie across a 64K
! 44: * DMA boundary.
! 45: *
! 46: * 93/07/03 bde
! 47: * Some floppy BIOS's can only handle reads of one track, so a LOADSZ
! 48: * of 16 doesn't work. 15 will do for now.
! 49: *
! 50: * 93/06/29 bde
! 51: * LOADSZ is 16, not 14. The BIOS can handle a minimum of one floppy
! 52: * cylinder so it can always handle 16 sectors starting at head 0,
! 53: * sector 1.
! 54: *
! 55: * 93/06/28 bde
! 56: * Changed addr16's to addr32's. One before a useless "xor %ecx, %ecx"
! 57: * did nothing (removed both prefix and xor).
! 58: *
! 59: * Initialize head = %dh = 0 for floppy case.
! 60: *
! 61: * Fixed #ifdef DEBUG ... #endif that split data32; jmp load. If
! 62: * DEBUG is defined then the jmp doesn't get prefixed. This is fatal
! 63: * iff the jmp is long. Usually the jmp will be short and the prefix
! 64: * unnecessary. But it is more likely to be necessary if DEBUG is
! 65: * defined.
! 66: *
! 67: * 93/06/27 bde
! 68: * Removed bogus Int 21. There is no Int 21 BIOS call. The drive
! 69: * number is passed to here in %dl and the Int 21 is at best a nop.
! 70: * Some BIOS's treat Int 21 as a stray hardware interrupt and shut
! 71: * down all in-service interrupts. This should not be a problem
! 72: * because this are not an interrupt handler so there are no
! 73: * in-service interrupts, but ...
! 74: *
! 75: * Fixed fd/hd decision. "%dl ge 0x80" (signed comparison) was always
! 76: * true, so fd's were treated as hd's. This was not a problem because
! 77: * the boot block has a partition table.
! 78: *
! 79: * Reduced BOOTSEG and added breakpoint so that debugger can look at
! 80: * this. Having a fixed boot address is bad because some machines don't
! 81: * have 640K and others have debuggers and/or BIOS stuff in high memory.
1.1 root 82: *
1.1.1.2 ! root 83: * 93/04/30 bde
! 84: * Commented out "<leading white space> # %". It's not C, and gcc-2's
! 85: * cpp doesn't allow it. "# identifier" isn't C either but works for now.
! 86: *
! 87: * Use $ EXT instead of $EXT to avoid broken DOLLARS_IN_IDENTIFIERS stuff
! 88: * in gcc-2.3.3. (Bug is still in gcc-2.4.5 but is avoided by using .S
! 89: * files.)
! 90: *
! 91: Revision 1.1 1993/03/21 18:08:42 cgd
! 92: after 0.2.2 "stable" patches applied
! 93:
1.1 root 94: * Revision 2.2 92/04/04 11:36:29 rpd
95: * Fix Intel Copyright as per B. Davies authorization.
96: * [92/04/03 rvb]
97: * Need to zero dh on hd path; at least for an adaptec card.
98: * [92/01/14 rvb]
99: *
100: * From 2.5 boot:
101: * Flush digit printing.
102: * Fuse floppy and hd boot by using Int 21 to tell
103: * boot type (slightly dubious since Int 21 is DOS
104: * not BIOS)
105: * [92/03/30 mg32]
106: *
107: * Revision 2.2 91/04/02 14:42:04 mbj
108: * Fix the BIG boot bug. We had missed a necessary data
109: * before a xor that was clearing a register used later
110: * as an index register.
111: * [91/03/01 rvb]
112: * Remember floppy type for swapgeneric
113: * Add Intel copyright
114: * [90/02/09 rvb]
115: *
116: */
117:
118:
119: /*
120: Copyright 1988, 1989, 1990, 1991, 1992
121: by Intel Corporation, Santa Clara, California.
122:
123: All Rights Reserved
124:
125: Permission to use, copy, modify, and distribute this software and
126: its documentation for any purpose and without fee is hereby
127: granted, provided that the above copyright notice appears in all
128: copies and that both the copyright notice and this permission notice
129: appear in supporting documentation, and that the name of Intel
130: not be used in advertising or publicity pertaining to distribution
131: of the software without specific, written prior permission.
132:
133: INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
134: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
135: IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
136: CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
137: LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
138: NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
139: WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
140: */
141: #include "asm.h"
142:
143: .file "start.s"
144:
1.1.1.2 ! root 145: BOOTSEG = 0x9000 # boot will be loaded here (below 640K)
1.1 root 146: BOOTSTACK = 0xe000 # boot stack
147: SIGNATURE = 0xaa55
1.1.1.2 ! root 148: LOADSZ = 15 # size of unix boot
1.1 root 149: PARTSTART = 0x1be # starting address of partition table
150: NUMPART = 4 # number of partitions in partition table
151: PARTSZ = 16 # each partition table entry is 16 bytes
152: BSDPART = 0xA5 # value of boot_ind, means bootable partition
153: BOOTABLE = 0x80 # value of boot_ind, means bootable partition
154:
155: .text
156:
157: ENTRY(boot1)
1.1.1.2 ! root 158: # start (aka boot1) is loaded at 0x0:0x7c00 but we want 0x7c0:0
! 159: # ljmp to the next instruction to adjust %cs
1.1 root 160: data32
161: ljmp $0x7c0, $start
162:
163: start:
164: # set up %ds
165: mov %cs, %ax
166: mov %ax, %ds
167:
168: # set up %ss and %esp
169: data32
170: mov $BOOTSEG, %eax
171: mov %ax, %ss
172: data32
173: mov $BOOTSTACK, %esp
174:
175: /*** set up %es, (where we will load boot2 to) ***/
176: mov %ax, %es
177:
178: #ifdef DEBUG
179: data32
180: mov $one, %esi
181: data32
182: call message
183: #endif
184:
1.1.1.2 ! root 185: # bootstrap passes us drive number in %dl
1.1 root 186: cmpb $0x80, %dl
187: data32
1.1.1.2 ! root 188: jae hd
1.1 root 189:
190: fd:
191: # reset the disk system
192: #ifdef DEBUG
193: data32
194: mov $two, %esi
195: data32
196: call message
197: #endif
198: movb $0x0, %ah
199: int $0x13
200: data32
201: mov $0x0001, %ecx # cyl 0, sector 1
1.1.1.2 ! root 202: movb $0, %dh # head
1.1 root 203: #ifdef DEBUG
204: data32
205: mov $three, %esi
206: data32
207: call message
208: #endif
1.1.1.2 ! root 209: data32
! 210: jmp load
1.1 root 211:
212: hd: /**** load sector 0 into the BOOTSEG ****/
213: #ifdef DEBUG
214: data32
215: mov $four, %esi
216: data32
217: call message
218: #endif
219: data32
220: mov $0x0201, %eax
221: xor %ebx, %ebx # %bx = 0
222: data32
223: mov $0x0001, %ecx
224: #ifdef DEBUG
225: data32
226: mov $five, %esi
227: data32
228: call message
229: #endif
230: data32
231: andl $0xff, %edx
232: /*mov $0x0080, %edx*/
233: int $0x13
234: data32
235: jb read_error
236:
1.1.1.2 ! root 237: /***# find the first 386BSD partition *****/
1.1 root 238: data32
239: mov $PARTSTART, %ebx
240: data32
241: mov $NUMPART, %ecx
242: again:
1.1.1.2 ! root 243: addr32
1.1 root 244: movb %es:4(%ebx), %al
245: cmpb $BSDPART, %al
246: data32
247: je found
248: data32
249: add $PARTSZ, %ebx
250: data32
251: loop again
252: data32
253: mov $enoboot, %esi
254: data32
255: jmp err_stop
256:
257:
258: /*
259: # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
260: # Call with %ah = 0x2
261: # %al = number of sectors
262: # %ch = cylinder
263: # %cl = sector
264: # %dh = head
265: # %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
266: # %es:%bx = segment:offset of buffer
267: # Return:
268: # %al = 0x0 on success; err code on failure
269: */
270:
271: found:
1.1.1.2 ! root 272: addr32
1.1 root 273: movb %es:1(%ebx), %dh /* head */
1.1.1.2 ! root 274: addr32
! 275: movl %es:2(%ebx), %ecx /*sect, cyl (+ 2 bytes junk in top word) */
1.1 root 276:
277: load:
278: movb $0x2, %ah /* function 2 */
279: movb $LOADSZ, %al /* number of blocks */
280: xor %ebx, %ebx /* %bx = 0, put it at 0 in the BOOTSEG */
281: int $0x13
282: data32
283: jb read_error
284:
285: # ljmp to the second stage boot loader (boot2).
286: # After ljmp, %cs is BOOTSEG and boot1 (512 bytes) will be used
287: # as an internal buffer "intbuf".
288:
289: #ifdef DEBUG
290: data32
291: mov $six, %esi
292: data32
293: call message
294: #endif
295: data32
1.1.1.2 ! root 296: ljmp $BOOTSEG, $ EXT(boot2)
1.1 root 297:
298: #
299: # read_error
300: #
301:
302: read_error:
303: data32
304: mov $eread, %esi
305: err_stop:
306: data32
307: call message
308: data32
309: jmp stop
310:
311: #
312: # message: write the error message in %ds:%esi to console
313: #
314:
315: message:
1.1.1.2 ! root 316: /*
1.1 root 317: # Use BIOS "int 10H Function 0Eh" to write character in teletype mode
318: # %ah = 0xe %al = character
319: # %bh = page %bl = foreground color (graphics modes)
1.1.1.2 ! root 320: */
1.1 root 321:
322: data32
323: push %eax
324: data32
325: push %ebx
326: data32
327: mov $0x0001, %ebx
328: cld
329:
330: nextb:
331: lodsb # load a byte into %al
332: cmpb $0x0, %al
333: data32
334: je done
335: movb $0xe, %ah
336: int $0x10 # display a byte
337: data32
338: jmp nextb
339: done:
340: data32
341: pop %ebx
342: data32
343: pop %eax
344: data32
345: ret
346:
347: stop: hlt
348: data32
349: jmp stop # halt doesnt actually halt forever
350:
351: /* error messages */
352:
353: #ifdef DEBUG
354: one: String "1\r\n\0"
355: two: String "2\r\n\0"
356: three: String "3\r\n\0"
357: four: String "4\r\n\0"
358: five: String "5\r\n\0"
359: six: String "6\r\n\0"
360: seven: String "7\r\n\0"
361: #endif DEBUG
362: eread: String "Read error\r\n\0"
363: enoboot: String "No bootable partition\r\n\0"
364: endofcode:
365: /* throw in a partition in case we are block0 as well */
1.1.1.2 ! root 366: /* flag, head, sec, cyl, typ, ehead, esect, ecyl, start, len */
1.1 root 367: . = EXT(boot1) + PARTSTART
368: .byte 0x0,0,0,0,0,0,0,0
369: .long 0,0
370: .byte 0x0,0,0,0,0,0,0,0
371: .long 0,0
372: .byte 0x0,0,0,0,0,0,0,0
373: .long 0,0
374: .byte BOOTABLE,0,1,0,BSDPART,255,255,255
375: .long 0,50000
376: /* the last 2 bytes in the sector 0 contain the signature */
377: . = EXT(boot1) + 0x1fe
378: .value SIGNATURE
379: ENTRY(disklabel)
380: . = EXT(boot1) + 0x400
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