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runkernel: remove debugging code
[syslinux.git] / isolinux.asm
blob42935645f1f41658f4d3b980359fb7bcd8a405ab
1 ; -*- fundamental -*- (asm-mode sucks)
2 ; ****************************************************************************
3 ;
4 ; isolinux.asm
5 ;
6 ; A program to boot Linux kernels off a CD-ROM using the El Torito
7 ; boot standard in "no emulation" mode, making the entire filesystem
8 ; available. It is based on the SYSLINUX boot loader for MS-DOS
9 ; floppies.
10 ;
11 ; Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
12 ;
13 ; This program is free software; you can redistribute it and/or modify
14 ; it under the terms of the GNU General Public License as published by
15 ; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
16 ; Boston MA 02111-1307, USA; either version 2 of the License, or
17 ; (at your option) any later version; incorporated herein by reference.
18 ;
19 ; ****************************************************************************
20
21 %define IS_ISOLINUX 1
22 %include "head.inc"
23
24 ;
25 ; Some semi-configurable constants... change on your own risk.
26 ;
27 my_id equ isolinux_id
28 FILENAME_MAX_LG2 equ 8 ; log2(Max filename size Including final null)
29 FILENAME_MAX equ (1 << FILENAME_MAX_LG2)
30 NULLFILE equ 0 ; Zero byte == null file name
31 NULLOFFSET equ 0 ; Position in which to look
32 retry_count equ 6 ; How patient are we with the BIOS?
33 %assign HIGHMEM_SLOP 128*1024 ; Avoid this much memory near the top
34 MAX_OPEN_LG2 equ 6 ; log2(Max number of open files)
35 MAX_OPEN equ (1 << MAX_OPEN_LG2)
36 SECTOR_SHIFT equ 11 ; 2048 bytes/sector (El Torito requirement)
37 SECTOR_SIZE equ (1 << SECTOR_SHIFT)
38
39 ;
40 ; This is what we need to do when idle
41 ;
42 %macro RESET_IDLE 0
43 ; Nothing
44 %endmacro
45 %macro DO_IDLE 0
46 ; Nothing
47 %endmacro
48
49 ;
50 ; The following structure is used for "virtual kernels"; i.e. LILO-style
51 ; option labels. The options we permit here are `kernel' and `append
52 ; Since there is no room in the bottom 64K for all of these, we
53 ; stick them in high memory and copy them down before we need them.
54 ;
55 struc vkernel
56 vk_vname: resb FILENAME_MAX ; Virtual name **MUST BE FIRST!**
57 vk_rname: resb FILENAME_MAX ; Real name
58 vk_appendlen: resw 1
59 vk_type: resb 1 ; Type of file
60 alignb 4
61 vk_append: resb max_cmd_len+1 ; Command line
62 alignb 4
63 vk_end: equ $ ; Should be <= vk_size
64 endstruc
65
66 ;
67 ; Segment assignments in the bottom 640K
68 ; 0000h - main code/data segment (and BIOS segment)
69 ;
70 real_mode_seg equ 2000h
71 xfer_buf_seg equ 1000h ; Bounce buffer for I/O to high mem
72 comboot_seg equ real_mode_seg ; COMBOOT image loading zone
73
74 ;
75 ; File structure. This holds the information for each currently open file.
76 ;
77 struc open_file_t
78 file_sector resd 1 ; Sector pointer (0 = structure free)
79 file_bytesleft resd 1 ; Number of bytes left
80 file_left resd 1 ; Number of sectors left
81 resd 1 ; Unused
82 endstruc
83
84 %ifndef DEPEND
85 %if (open_file_t_size & (open_file_t_size-1))
86 %error "open_file_t is not a power of 2"
87 %endif
88 %endif
89
90 struc dir_t
91 dir_lba resd 1 ; Directory start (LBA)
92 dir_len resd 1 ; Length in bytes
93 dir_clust resd 1 ; Length in clusters
94 endstruc
95
96 ; ---------------------------------------------------------------------------
97 ; BEGIN CODE
98 ; ---------------------------------------------------------------------------
99
100 ;
101 ; Memory below this point is reserved for the BIOS and the MBR
102 ;
103 section .earlybss
104 trackbufsize equ 8192
105 trackbuf resb trackbufsize ; Track buffer goes here
106 ; ends at 2800h
107
108 ; Some of these are touched before the whole image
109 ; is loaded. DO NOT move this to .uibss.
110 section .bss2
111 alignb 4
112 ISOFileName resb 64 ; ISO filename canonicalization buffer
113 ISOFileNameEnd equ $
114 CurDir resb dir_t_size ; Current directory
115 RootDir resb dir_t_size ; Root directory
116 FirstSecSum resd 1 ; Checksum of bytes 64-2048
117 ImageDwords resd 1 ; isolinux.bin size, dwords
118 InitStack resd 1 ; Initial stack pointer (SS:SP)
119 DiskSys resw 1 ; Last INT 13h call
120 ImageSectors resw 1 ; isolinux.bin size, sectors
121 DiskError resb 1 ; Error code for disk I/O
122 DriveNumber resb 1 ; CD-ROM BIOS drive number
123 ISOFlags resb 1 ; Flags for ISO directory search
124 RetryCount resb 1 ; Used for disk access retries
125
126 _spec_start equ $
127
128 ;
129 ; El Torito spec packet
130 ;
131
132 alignb 8
133 spec_packet: resb 1 ; Size of packet
134 sp_media: resb 1 ; Media type
135 sp_drive: resb 1 ; Drive number
136 sp_controller: resb 1 ; Controller index
137 sp_lba: resd 1 ; LBA for emulated disk image
138 sp_devspec: resw 1 ; IDE/SCSI information
139 sp_buffer: resw 1 ; User-provided buffer
140 sp_loadseg: resw 1 ; Load segment
141 sp_sectors: resw 1 ; Sector count
142 sp_chs: resb 3 ; Simulated CHS geometry
143 sp_dummy: resb 1 ; Scratch, safe to overwrite
144
145 ;
146 ; EBIOS drive parameter packet
147 ;
148 alignb 8
149 drive_params: resw 1 ; Buffer size
150 dp_flags: resw 1 ; Information flags
151 dp_cyl: resd 1 ; Physical cylinders
152 dp_head: resd 1 ; Physical heads
153 dp_sec: resd 1 ; Physical sectors/track
154 dp_totalsec: resd 2 ; Total sectors
155 dp_secsize: resw 1 ; Bytes per sector
156 dp_dpte: resd 1 ; Device Parameter Table
157 dp_dpi_key: resw 1 ; 0BEDDh if rest valid
158 dp_dpi_len: resb 1 ; DPI len
159 resb 1
160 resw 1
161 dp_bus: resb 4 ; Host bus type
162 dp_interface: resb 8 ; Interface type
163 db_i_path: resd 2 ; Interface path
164 db_d_path: resd 2 ; Device path
165 resb 1
166 db_dpi_csum: resb 1 ; Checksum for DPI info
167
168 ;
169 ; EBIOS disk address packet
170 ;
171 alignb 8
172 dapa: resw 1 ; Packet size
173 .count: resw 1 ; Block count
174 .off: resw 1 ; Offset of buffer
175 .seg: resw 1 ; Segment of buffer
176 .lba: resd 2 ; LBA (LSW, MSW)
177
178 ;
179 ; Spec packet for disk image emulation
180 ;
181 alignb 8
182 dspec_packet: resb 1 ; Size of packet
183 dsp_media: resb 1 ; Media type
184 dsp_drive: resb 1 ; Drive number
185 dsp_controller: resb 1 ; Controller index
186 dsp_lba: resd 1 ; LBA for emulated disk image
187 dsp_devspec: resw 1 ; IDE/SCSI information
188 dsp_buffer: resw 1 ; User-provided buffer
189 dsp_loadseg: resw 1 ; Load segment
190 dsp_sectors: resw 1 ; Sector count
191 dsp_chs: resb 3 ; Simulated CHS geometry
192 dsp_dummy: resb 1 ; Scratch, safe to overwrite
193
194 alignb 4
195 _spec_end equ $
196 _spec_len equ _spec_end - _spec_start
197
198 alignb open_file_t_size
199 Files resb MAX_OPEN*open_file_t_size
200
201 section .text
202 ;;
203 ;; Primary entry point. Because BIOSes are buggy, we only load the first
204 ;; CD-ROM sector (2K) of the file, so the number one priority is actually
205 ;; loading the rest.
206 ;;
207 StackBuf equ $-44 ; 44 bytes needed for
208 ; the bootsector chainloading
209 ; code!
210 OrigESDI equ StackBuf-4 ; The high dword on the stack
211
212 bootsec equ $
213
214 _start: ; Far jump makes sure we canonicalize the address
215 cli
216 jmp 0:_start1
217 times 8-($-$$) nop ; Pad to file offset 8
218
219 ; This table hopefully gets filled in by mkisofs using the
220 ; -boot-info-table option. If not, the values in this
221 ; table are default values that we can use to get us what
222 ; we need, at least under a certain set of assumptions.
223 bi_pvd: dd 16 ; LBA of primary volume descriptor
224 bi_file: dd 0 ; LBA of boot file
225 bi_length: dd 0xdeadbeef ; Length of boot file
226 bi_csum: dd 0xdeadbeef ; Checksum of boot file
227 bi_reserved: times 10 dd 0xdeadbeef ; Reserved
228
229 _start1: mov [cs:InitStack],sp ; Save initial stack pointer
230 mov [cs:InitStack+2],ss
231 xor ax,ax
232 mov ss,ax
233 mov sp,StackBuf ; Set up stack
234 push es ; Save initial ES:DI -> $PnP pointer
235 push di
236 mov ds,ax
237 mov es,ax
238 mov fs,ax
239 mov gs,ax
240 sti
241
242 cld
243 ; Show signs of life
244 mov si,syslinux_banner
245 call writestr
246 %ifdef DEBUG_MESSAGES
247 mov si,copyright_str
248 call writestr
249 %endif
250
251 ;
252 ; Before modifying any memory, get the checksum of bytes
253 ; 64-2048
254 ;
255 initial_csum: xor edi,edi
256 mov si,_start1
257 mov cx,(SECTOR_SIZE-64) >> 2
258 .loop: lodsd
259 add edi,eax
260 loop .loop
261 mov [FirstSecSum],edi
262
263 mov [DriveNumber],dl
264 %ifdef DEBUG_MESSAGES
265 mov si,startup_msg
266 call writemsg
267 mov al,dl
268 call writehex2
269 call crlf
270 %endif
271 ;
272 ; Initialize spec packet buffers
273 ;
274 mov di,_spec_start
275 mov cx,_spec_len >> 2
276 xor eax,eax
277 rep stosd
278
279 ; Initialize length field of the various packets
280 mov byte [spec_packet],13h
281 mov byte [drive_params],30
282 mov byte [dapa],16
283 mov byte [dspec_packet],13h
284
285 ; Other nonzero fields
286 inc word [dsp_sectors]
287
288 ; Now figure out what we're actually doing
289 ; Note: use passed-in DL value rather than 7Fh because
290 ; at least some BIOSes will get the wrong value otherwise
291 mov ax,4B01h ; Get disk emulation status
292 mov dl,[DriveNumber]
293 mov si,spec_packet
294 call int13
295 jc award_hack ; changed for BrokenAwardHack
296 mov dl,[DriveNumber]
297 cmp [sp_drive],dl ; Should contain the drive number
298 jne spec_query_failed
299
300 %ifdef DEBUG_MESSAGES
301 mov si,spec_ok_msg
302 call writemsg
303 mov al,byte [sp_drive]
304 call writehex2
305 call crlf
306 %endif
307
308 found_drive:
309 ; Alright, we have found the drive. Now, try to find the
310 ; boot file itself. If we have a boot info table, life is
311 ; good; if not, we have to make some assumptions, and try
312 ; to figure things out ourselves. In particular, the
313 ; assumptions we have to make are:
314 ; - single session only
315 ; - only one boot entry (no menu or other alternatives)
316
317 cmp dword [bi_file],0 ; Address of code to load
318 jne found_file ; Boot info table present :)
319
320 %ifdef DEBUG_MESSAGES
321 mov si,noinfotable_msg
322 call writemsg
323 %endif
324
325 ; No such luck. See if the spec packet contained one.
326 mov eax,[sp_lba]
327 and eax,eax
328 jz set_file ; Good enough
329
330 %ifdef DEBUG_MESSAGES
331 mov si,noinfoinspec_msg
332 call writemsg
333 %endif
334
335 ; No such luck. Get the Boot Record Volume, assuming single
336 ; session disk, and that we're the first entry in the chain
337 mov eax,17 ; Assumed address of BRV
338 mov bx,trackbuf
339 call getonesec
340
341 mov eax,[trackbuf+47h] ; Get boot catalog address
342 mov bx,trackbuf
343 call getonesec ; Get boot catalog
344
345 mov eax,[trackbuf+28h] ; First boot entry
346 ; And hope and pray this is us...
347
348 ; Some BIOSes apparently have limitations on the size
349 ; that may be loaded (despite the El Torito spec being very
350 ; clear on the fact that it must all be loaded.) Therefore,
351 ; we load it ourselves, and *bleep* the BIOS.
352
353 set_file:
354 mov [bi_file],eax
355
356 found_file:
357 ; Set up boot file sizes
358 mov eax,[bi_length]
359 sub eax,SECTOR_SIZE-3
360 shr eax,2 ; bytes->dwords
361 mov [ImageDwords],eax ; boot file dwords
362 add eax,(2047 >> 2)
363 shr eax,9 ; dwords->sectors
364 mov [ImageSectors],ax ; boot file sectors
365
366 mov eax,[bi_file] ; Address of code to load
367 inc eax ; Don't reload bootstrap code
368 %ifdef DEBUG_MESSAGES
369 mov si,offset_msg
370 call writemsg
371 call writehex8
372 call crlf
373 %endif
374
375 ; Just in case some BIOSes have problems with
376 ; segment wraparound, use the normalized address
377 mov bx,((7C00h+2048) >> 4)
378 mov es,bx
379 xor bx,bx
380 mov bp,[ImageSectors]
381 %ifdef DEBUG_MESSAGES
382 push ax
383 mov si,size_msg
384 call writemsg
385 mov ax,bp
386 call writehex4
387 call crlf
388 pop ax
389 %endif
390 call getlinsec
391
392 push ds
393 pop es
394
395 %ifdef DEBUG_MESSAGES
396 mov si,loaded_msg
397 call writemsg
398 %endif
399
400 ; Verify the checksum on the loaded image.
401 verify_image:
402 mov si,7C00h+2048
403 mov bx,es
404 mov ecx,[ImageDwords]
405 mov edi,[FirstSecSum] ; First sector checksum
406 .loop es lodsd
407 add edi,eax
408 dec ecx
409 jz .done
410 and si,si
411 jnz .loop
412 ; SI wrapped around, advance ES
413 add bx,1000h
414 mov es,bx
415 jmp short .loop
416 .done: mov ax,ds
417 mov es,ax
418 cmp [bi_csum],edi
419 je integrity_ok
420
421 mov si,checkerr_msg
422 call writemsg
423 jmp kaboom
424
425 integrity_ok:
426 %ifdef DEBUG_MESSAGES
427 mov si,allread_msg
428 call writemsg
429 %endif
430 jmp all_read ; Jump to main code
431
432 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
433 ;; Start of BrokenAwardHack --- 10-nov-2002 Knut_Petersen@t-online.de
434 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
435 ;;
436 ;; There is a problem with certain versions of the AWARD BIOS ...
437 ;; the boot sector will be loaded and executed correctly, but, because the
438 ;; int 13 vector points to the wrong code in the BIOS, every attempt to
439 ;; load the spec packet will fail. We scan for the equivalent of
440 ;;
441 ;; mov ax,0201h
442 ;; mov bx,7c00h
443 ;; mov cx,0006h
444 ;; mov dx,0180h
445 ;; pushf
446 ;; call <direct far>
447 ;;
448 ;; and use <direct far> as the new vector for int 13. The code above is
449 ;; used to load the boot code into ram, and there should be no reason
450 ;; for anybody to change it now or in the future. There are no opcodes
451 ;; that use encodings relativ to IP, so scanning is easy. If we find the
452 ;; code above in the BIOS code we can be pretty sure to run on a machine
453 ;; with an broken AWARD BIOS ...
454 ;;
455 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
456 ;;
457 %ifdef DEBUG_MESSAGES ;;
458 ;;
459 award_notice db "Trying BrokenAwardHack first ...",CR,LF,0 ;;
460 award_not_orig db "BAH: Original Int 13 vector : ",0 ;;
461 award_not_new db "BAH: Int 13 vector changed to : ",0 ;;
462 award_not_succ db "BAH: SUCCESS",CR,LF,0 ;;
463 award_not_fail db "BAH: FAILURE" ;;
464 award_not_crlf db CR,LF,0 ;;
465 ;;
466 %endif ;;
467 ;;
468 award_oldint13 dd 0 ;;
469 award_string db 0b8h,1,2,0bbh,0,7ch,0b9h,6,0,0bah,80h,1,09ch,09ah ;;
470 ;;
471 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
472 award_hack: mov si,spec_err_msg ; Moved to this place from
473 call writemsg ; spec_query_faild
474 ;
475 %ifdef DEBUG_MESSAGES ;
476 ;
477 mov si,award_notice ; display our plan
478 call writemsg ;
479 mov si,award_not_orig ; display original int 13
480 call writemsg ; vector
481 %endif ;
482 mov eax,[13h*4] ;
483 mov [award_oldint13],eax ;
484 ;
485 %ifdef DEBUG_MESSAGES ;
486 ;
487 call writehex8 ;
488 mov si,award_not_crlf ;
489 call writestr ;
490 %endif ;
491 push es ; save ES
492 mov ax,0f000h ; ES = BIOS Seg
493 mov es,ax ;
494 cld ;
495 xor di,di ; start at ES:DI = f000:0
496 award_loop: push di ; save DI
497 mov si,award_string ; scan for award_string
498 mov cx,7 ; length of award_string = 7dw
499 repz cmpsw ; compare
500 pop di ; restore DI
501 jcxz award_found ; jmp if found
502 inc di ; not found, inc di
503 jno award_loop ;
504 ;
505 award_failed: pop es ; No, not this way :-((
506 award_fail2: ;
507 ;
508 %ifdef DEBUG_MESSAGES ;
509 ;
510 mov si,award_not_fail ; display failure ...
511 call writemsg ;
512 %endif ;
513 mov eax,[award_oldint13] ; restore the original int
514 or eax,eax ; 13 vector if there is one
515 jz spec_query_failed ; and try other workarounds
516 mov [13h*4],eax ;
517 jmp spec_query_failed ;
518 ;
519 award_found: mov eax,[es:di+0eh] ; load possible int 13 addr
520 pop es ; restore ES
521 ;
522 cmp eax,[award_oldint13] ; give up if this is the
523 jz award_failed ; active int 13 vector,
524 mov [13h*4],eax ; otherwise change 0:13h*4
525 ;
526 ;
527 %ifdef DEBUG_MESSAGES ;
528 ;
529 push eax ; display message and
530 mov si,award_not_new ; new vector address
531 call writemsg ;
532 pop eax ;
533 call writehex8 ;
534 mov si,award_not_crlf ;
535 call writestr ;
536 %endif ;
537 mov ax,4B01h ; try to read the spec packet
538 mov dl,[DriveNumber] ; now ... it should not fail
539 mov si,spec_packet ; any longer
540 int 13h ;
541 jc award_fail2 ;
542 ;
543 %ifdef DEBUG_MESSAGES ;
544 ;
545 mov si,award_not_succ ; display our SUCCESS
546 call writemsg ;
547 %endif ;
548 jmp found_drive ; and leave error recovery code
549 ;
550 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
551 ;; End of BrokenAwardHack ---- 10-nov-2002 Knut_Petersen@t-online.de
552 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
553
554
555 ; INT 13h, AX=4B01h, DL=<passed in value> failed.
556 ; Try to scan the entire 80h-FFh from the end.
557
558 spec_query_failed:
559
560 ; some code moved to BrokenAwardHack
561
562 mov dl,0FFh
563 .test_loop: pusha
564 mov ax,4B01h
565 mov si,spec_packet
566 mov byte [si],13h ; Size of buffer
567 call int13
568 popa
569 jc .still_broken
570
571 mov si,maybe_msg
572 call writemsg
573 mov al,dl
574 call writehex2
575 call crlf
576
577 cmp byte [sp_drive],dl
578 jne .maybe_broken
579
580 ; Okay, good enough...
581 mov si,alright_msg
582 call writemsg
583 .found_drive0: mov [DriveNumber],dl
584 .found_drive: jmp found_drive
585
586 ; Award BIOS 4.51 apparently passes garbage in sp_drive,
587 ; but if this was the drive number originally passed in
588 ; DL then consider it "good enough"
589 .maybe_broken:
590 mov al,[DriveNumber]
591 cmp al,dl
592 je .found_drive
593
594 ; Intel Classic R+ computer with Adaptec 1542CP BIOS 1.02
595 ; passes garbage in sp_drive, and the drive number originally
596 ; passed in DL does not have 80h bit set.
597 or al,80h
598 cmp al,dl
599 je .found_drive0
600
601 .still_broken: dec dx
602 cmp dl, 80h
603 jnb .test_loop
604
605 ; No spec packet anywhere. Some particularly pathetic
606 ; BIOSes apparently don't even implement function
607 ; 4B01h, so we can't query a spec packet no matter
608 ; what. If we got a drive number in DL, then try to
609 ; use it, and if it works, then well...
610 mov dl,[DriveNumber]
611 cmp dl,81h ; Should be 81-FF at least
612 jb fatal_error ; If not, it's hopeless
613
614 ; Write a warning to indicate we're on *very* thin ice now
615 mov si,nospec_msg
616 call writemsg
617 mov al,dl
618 call writehex2
619 call crlf
620 mov si,trysbm_msg
621 call writemsg
622 jmp .found_drive ; Pray that this works...
623
624 fatal_error:
625 mov si,nothing_msg
626 call writemsg
627
628 .norge: jmp short .norge
629
630 ; Information message (DS:SI) output
631 ; Prefix with "isolinux: "
632 ;
633 writemsg: push ax
634 push si
635 mov si,isolinux_str
636 call writestr
637 pop si
638 call writestr
639 pop ax
640 ret
641
642 ;
643 ; Write a character to the screen. There is a more "sophisticated"
644 ; version of this in the subsequent code, so we patch the pointer
645 ; when appropriate.
646 ;
647
648 writechr:
649 jmp near writechr_simple ; 3-byte jump
650
651 writechr_simple:
652 pushfd
653 pushad
654 mov ah,0Eh
655 xor bx,bx
656 int 10h
657 popad
658 popfd
659 ret
660
661 ;
662 ; int13: save all the segment registers and call INT 13h
663 ; Some CD-ROM BIOSes have been found to corrupt segment registers.
664 ;
665 int13:
666
667 push ds
668 push es
669 push fs
670 push gs
671 int 13h
672 pop gs
673 pop fs
674 pop es
675 pop ds
676 ret
677
678 ;
679 ; Get one sector. Convenience entry point.
680 ;
681 getonesec:
682 mov bp,1
683 ; Fall through to getlinsec
684
685 ;
686 ; Get linear sectors - EBIOS LBA addressing, 2048-byte sectors.
687 ;
688 ; Note that we can't always do this as a single request, because at least
689 ; Phoenix BIOSes has a 127-sector limit. To be on the safe side, stick
690 ; to 32 sectors (64K) per request.
691 ;
692 ; Input:
693 ; EAX - Linear sector number
694 ; ES:BX - Target buffer
695 ; BP - Sector count
696 ;
697 getlinsec:
698 mov si,dapa ; Load up the DAPA
699 mov [si+4],bx
700 mov bx,es
701 mov [si+6],bx
702 mov [si+8],eax
703 .loop:
704 push bp ; Sectors left
705 cmp bp,[MaxTransfer]
706 jbe .bp_ok
707 mov bp,[MaxTransfer]
708 .bp_ok:
709 mov [si+2],bp
710 push si
711 mov dl,[DriveNumber]
712 mov ah,42h ; Extended Read
713 call xint13
714 pop si
715 pop bp
716 movzx eax,word [si+2] ; Sectors we read
717 add [si+8],eax ; Advance sector pointer
718 sub bp,ax ; Sectors left
719 shl ax,SECTOR_SHIFT-4 ; 2048-byte sectors -> segment
720 add [si+6],ax ; Advance buffer pointer
721 and bp,bp
722 jnz .loop
723 mov eax,[si+8] ; Next sector
724 ret
725
726 ; INT 13h with retry
727 xint13: mov byte [RetryCount],retry_count
728 .try: pushad
729 call int13
730 jc .error
731 add sp,byte 8*4 ; Clean up stack
732 ret
733 .error:
734 mov [DiskError],ah ; Save error code
735 popad
736 mov [DiskSys],ax ; Save system call number
737 dec byte [RetryCount]
738 jz .real_error
739 push ax
740 mov al,[RetryCount]
741 mov ah,[dapa+2] ; Sector transfer count
742 cmp al,2 ; Only 2 attempts left
743 ja .nodanger
744 mov ah,1 ; Drop transfer size to 1
745 jmp short .setsize
746 .nodanger:
747 cmp al,retry_count-2
748 ja .again ; First time, just try again
749 shr ah,1 ; Otherwise, try to reduce
750 adc ah,0 ; the max transfer size, but not to 0
751 .setsize:
752 mov [MaxTransfer],ah
753 mov [dapa+2],ah
754 .again:
755 pop ax
756 jmp .try
757
758 .real_error: mov si,diskerr_msg
759 call writemsg
760 mov al,[DiskError]
761 call writehex2
762 mov si,oncall_str
763 call writestr
764 mov ax,[DiskSys]
765 call writehex4
766 mov si,ondrive_str
767 call writestr
768 mov al,dl
769 call writehex2
770 call crlf
771 ; Fall through to kaboom
772
773 ;
774 ; kaboom: write a message and bail out. Wait for a user keypress,
775 ; then do a hard reboot.
776 ;
777 kaboom:
778 RESET_STACK_AND_SEGS AX
779 mov si,err_bootfailed
780 call cwritestr
781 call getchar
782 cli
783 mov word [BIOS_magic],0 ; Cold reboot
784 jmp 0F000h:0FFF0h ; Reset vector address
785
786 ; -----------------------------------------------------------------------------
787 ; Common modules needed in the first sector
788 ; -----------------------------------------------------------------------------
789
790 %include "writestr.inc" ; String output
791 writestr equ cwritestr
792 %include "writehex.inc" ; Hexadecimal output
793
794 ; -----------------------------------------------------------------------------
795 ; Data that needs to be in the first sector
796 ; -----------------------------------------------------------------------------
797
798 syslinux_banner db CR, LF, 'ISOLINUX ', version_str, ' ', date, ' ', 0
799 copyright_str db ' Copyright (C) 1994-', year, ' H. Peter Anvin'
800 db CR, LF, 0
801 isolinux_str db 'isolinux: ', 0
802 %ifdef DEBUG_MESSAGES
803 startup_msg: db 'Starting up, DL = ', 0
804 spec_ok_msg: db 'Loaded spec packet OK, drive = ', 0
805 secsize_msg: db 'Sector size appears to be ', 0
806 offset_msg: db 'Loading main image from LBA = ', 0
807 size_msg: db 'Sectors to load = ', 0
808 loaded_msg: db 'Loaded boot image, verifying...', CR, LF, 0
809 verify_msg: db 'Image checksum verified.', CR, LF, 0
810 allread_msg db 'Main image read, jumping to main code...', CR, LF, 0
811 %endif
812 noinfotable_msg db 'No boot info table, assuming single session disk...', CR, LF, 0
813 noinfoinspec_msg db 'Spec packet missing LBA information, trying to wing it...', CR, LF, 0
814 spec_err_msg: db 'Loading spec packet failed, trying to wing it...', CR, LF, 0
815 maybe_msg: db 'Found something at drive = ', 0
816 alright_msg: db 'Looks like it might be right, continuing...', CR, LF, 0
817 nospec_msg db 'Extremely broken BIOS detected, last ditch attempt with drive = ', 0
818 nothing_msg: db 'Failed to locate CD-ROM device; boot failed.', CR, LF
819 trysbm_msg db 'See http://syslinux.zytor.com/sbm for more information.', CR, LF, 0
820 diskerr_msg: db 'Disk error ', 0
821 oncall_str: db ', AX = ',0
822 ondrive_str: db ', drive ', 0
823 checkerr_msg: db 'Image checksum error, sorry...', CR, LF, 0
824
825 err_bootfailed db CR, LF, 'Boot failed: press a key to retry...'
826 bailmsg equ err_bootfailed
827 crlf_msg db CR, LF
828 null_msg db 0
829
830 alignb 4, db 0
831 MaxTransfer dw 32 ; Max sectors per transfer
832
833 rl_checkpt equ $ ; Must be <= 800h
834
835 rl_checkpt_off equ ($-$$)
836 ;%ifndef DEPEND
837 ;%if rl_checkpt_off > 0x800
838 ;%error "Sector 0 overflow"
839 ;%endif
840 ;%endif
841
842 ; ----------------------------------------------------------------------------
843 ; End of code and data that have to be in the first sector
844 ; ----------------------------------------------------------------------------
845
846 all_read:
847
848 ; Test tracers
849 TRACER 'T'
850 TRACER '>'
851
852 ;
853 ; Common initialization code
854 ;
855 %include "init.inc"
856 %include "cpuinit.inc"
857
858 ; Patch the writechr routine to point to the full code
859 mov word [writechr+1], writechr_full-(writechr+3)
860
861 ; Tell the user we got this far...
862 %ifndef DEBUG_MESSAGES ; Gets messy with debugging on
863 mov si,copyright_str
864 call writestr
865 %endif
866
867 ;
868 ; Now we're all set to start with our *real* business. First load the
869 ; configuration file (if any) and parse it.
870 ;
871 ; In previous versions I avoided using 32-bit registers because of a
872 ; rumour some BIOSes clobbered the upper half of 32-bit registers at
873 ; random. I figure, though, that if there are any of those still left
874 ; they probably won't be trying to install Linux on them...
875 ;
876 ; The code is still ripe with 16-bitisms, though. Not worth the hassle
877 ; to take'm out. In fact, we may want to put them back if we're going
878 ; to boot ELKS at some point.
879 ;
880
881 ;
882 ; Now, we need to sniff out the actual filesystem data structures.
883 ; mkisofs gave us a pointer to the primary volume descriptor
884 ; (which will be at 16 only for a single-session disk!); from the PVD
885 ; we should be able to find the rest of what we need to know.
886 ;
887 get_fs_structures:
888 mov eax,[bi_pvd]
889 mov bx,trackbuf
890 call getonesec
891
892 mov eax,[trackbuf+156+2]
893 mov [RootDir+dir_lba],eax
894 mov [CurDir+dir_lba],eax
895 %ifdef DEBUG_MESSAGES
896 mov si,dbg_rootdir_msg
897 call writemsg
898 call writehex8
899 call crlf
900 %endif
901 mov eax,[trackbuf+156+10]
902 mov [RootDir+dir_len],eax
903 mov [CurDir+dir_len],eax
904 add eax,SECTOR_SIZE-1
905 shr eax,SECTOR_SHIFT
906 mov [RootDir+dir_clust],eax
907 mov [CurDir+dir_clust],eax
908
909 ; Look for an isolinux directory, and if found,
910 ; make it the current directory instead of the root
911 ; directory.
912 mov di,boot_dir ; Search for /boot/isolinux
913 mov al,02h
914 call searchdir_iso
915 jnz .found_dir
916 mov di,isolinux_dir
917 mov al,02h ; Search for /isolinux
918 call searchdir_iso
919 jz .no_isolinux_dir
920 .found_dir:
921 mov [CurDir+dir_len],eax
922 mov eax,[si+file_left]
923 mov [CurDir+dir_clust],eax
924 xor eax,eax ; Free this file pointer entry
925 xchg eax,[si+file_sector]
926 mov [CurDir+dir_lba],eax
927 %ifdef DEBUG_MESSAGES
928 push si
929 mov si,dbg_isodir_msg
930 call writemsg
931 pop si
932 call writehex8
933 call crlf
934 %endif
935 .no_isolinux_dir:
936
937 ;
938 ; Locate the configuration file
939 ;
940 load_config:
941 %ifdef DEBUG_MESSAGES
942 mov si,dbg_config_msg
943 call writemsg
944 %endif
945
946 mov si,config_name
947 mov di,ConfigName
948 call strcpy
949
950 mov di,ConfigName
951 call open
952 jz no_config_file ; Not found or empty
953
954 %ifdef DEBUG_MESSAGES
955 mov si,dbg_configok_msg
956 call writemsg
957 %endif
958
959 ;
960 ; Now we have the config file open. Parse the config file and
961 ; run the user interface.
962 ;
963 %include "ui.inc"
964
965 ;
966 ; Enable disk emulation. The kind of disk we emulate is dependent on the
967 ; size of the file: 1200K, 1440K or 2880K floppy, otherwise harddisk.
968 ;
969 is_disk_image:
970 TRACER CR
971 TRACER LF
972 TRACER 'D'
973 TRACER ':'
974
975 mov edx,eax ; File size
976 mov di,img_table
977 mov cx,img_table_count
978 mov eax,[si+file_sector] ; Starting LBA of file
979 mov [dsp_lba],eax ; Location of file
980 mov byte [dsp_drive], 0 ; 00h floppy, 80h hard disk
981 .search_table:
982 TRACER 't'
983 mov eax,[di+4]
984 cmp edx,[di]
985 je .type_found
986 add di,8
987 loop .search_table
988
989 ; Hard disk image. Need to examine the partition table
990 ; in order to deduce the C/H/S geometry. Sigh.
991 .hard_disk_image:
992 TRACER 'h'
993 cmp edx,512
994 jb .bad_image
995
996 mov bx,trackbuf
997 mov cx,1 ; Load 1 sector
998 call getfssec
999
1000 cmp word [trackbuf+510],0aa55h ; Boot signature
1001 jne .bad_image ; Image not bootable
1002
1003 mov cx,4 ; 4 partition entries
1004 mov di,trackbuf+446 ; Start of partition table
1005
1006 xor ax,ax ; Highest sector(al) head(ah)
1007
1008 .part_scan:
1009 cmp byte [di+4], 0
1010 jz .part_loop
1011 lea si,[di+1]
1012 call .hs_check
1013 add si,byte 4
1014 call .hs_check
1015 .part_loop:
1016 add di,byte 16
1017 loop .part_scan
1018
1019 push eax ; H/S
1020 push edx ; File size
1021 mov bl,ah
1022 xor bh,bh
1023 inc bx ; # of heads in BX
1024 xor ah,ah ; # of sectors in AX
1025 cwde ; EAX[31:16] <- 0
1026 mul bx
1027 shl eax,9 ; Convert to bytes
1028 ; Now eax contains the number of bytes per cylinder
1029 pop ebx ; File size
1030 xor edx,edx
1031 div ebx
1032 and edx,edx
1033 jz .no_remainder
1034 inc eax ; Fractional cylinder...
1035 ; Now (e)ax contains the number of cylinders
1036 .no_remainder: cmp eax,1024
1037 jna .ok_cyl
1038 mov ax,1024 ; Max possible #
1039 .ok_cyl: dec ax ; Convert to max cylinder no
1040 pop ebx ; S(bl) H(bh)
1041 shl ah,6
1042 or bl,ah
1043 xchg ax,bx
1044 shl eax,16
1045 mov ah,bl
1046 mov al,4 ; Hard disk boot
1047 mov byte [dsp_drive], 80h ; Drive 80h = hard disk
1048
1049 .type_found:
1050 TRACER 'T'
1051 mov bl,[sp_media]
1052 and bl,0F0h ; Copy controller info bits
1053 or al,bl
1054 mov [dsp_media],al ; Emulation type
1055 shr eax,8
1056 mov [dsp_chs],eax ; C/H/S geometry
1057 mov ax,[sp_devspec] ; Copy device spec
1058 mov [dsp_devspec],ax
1059 mov al,[sp_controller] ; Copy controller index
1060 mov [dsp_controller],al
1061
1062 TRACER 'V'
1063 call vgaclearmode ; Reset video
1064
1065 mov ax,4C00h ; Enable emulation and boot
1066 mov si,dspec_packet
1067 mov dl,[DriveNumber]
1068 lss sp,[InitStack]
1069 TRACER 'X'
1070
1071 call int13
1072
1073 ; If this returns, we have problems
1074 .bad_image:
1075 mov si,err_disk_image
1076 call cwritestr
1077 jmp enter_command
1078
1079 ;
1080 ; Look for the highest seen H/S geometry
1081 ; We compute cylinders separately
1082 ;
1083 .hs_check:
1084 mov bl,[si] ; Head #
1085 cmp bl,ah
1086 jna .done_track
1087 mov ah,bl ; New highest head #
1088 .done_track: mov bl,[si+1]
1089 and bl,3Fh ; Sector #
1090 cmp bl,al
1091 jna .done_sector
1092 mov al,bl
1093 .done_sector: ret
1094
1095 ;
1096 ; Boot a specified local disk. AX specifies the BIOS disk number; or
1097 ; 0xFFFF in case we should execute INT 18h ("next device.")
1098 ;
1099 local_boot:
1100 call vgaclearmode
1101 lss sp,[cs:Stack] ; Restore stack pointer
1102 xor dx,dx
1103 mov ds,dx
1104 mov es,dx
1105 mov fs,dx
1106 mov gs,dx
1107 mov si,localboot_msg
1108 call writestr
1109 cmp ax,-1
1110 je .int18
1111
1112 ; Load boot sector from the specified BIOS device and jump to it.
1113 mov dl,al
1114 xor dh,dh
1115 push dx
1116 xor ax,ax ; Reset drive
1117 call xint13
1118 mov ax,0201h ; Read one sector
1119 mov cx,0001h ; C/H/S = 0/0/1 (first sector)
1120 mov bx,trackbuf
1121 call xint13
1122 pop dx
1123 cli ; Abandon hope, ye who enter here
1124 mov si,trackbuf
1125 mov di,07C00h
1126 mov cx,512 ; Probably overkill, but should be safe
1127 rep movsd
1128 lss sp,[cs:InitStack]
1129 jmp 0:07C00h ; Jump to new boot sector
1130
1131 .int18:
1132 int 18h ; Hope this does the right thing...
1133 jmp kaboom ; If we returned, oh boy...
1134
1135 ;
1136 ; close_file:
1137 ; Deallocates a file structure (pointer in SI)
1138 ; Assumes CS == DS.
1139 ;
1140 close_file:
1141 and si,si
1142 jz .closed
1143 mov dword [si],0 ; First dword == file_left
1144 xor si,si
1145 .closed: ret
1146
1147 ;
1148 ; searchdir:
1149 ;
1150 ; Open a file
1151 ;
1152 ; On entry:
1153 ; DS:DI = filename
1154 ; If successful:
1155 ; ZF clear
1156 ; SI = file pointer
1157 ; EAX = file length in bytes
1158 ; If unsuccessful
1159 ; ZF set
1160 ;
1161 ; Assumes CS == DS == ES, and trashes BX and CX.
1162 ;
1163 ; searchdir_iso is a special entry point for ISOLINUX only. In addition
1164 ; to the above, searchdir_iso passes a file flag mask in AL. This is useful
1165 ; for searching for directories.
1166 ;
1167 alloc_failure:
1168 xor ax,ax ; ZF <- 1
1169 ret
1170
1171 searchdir:
1172 xor al,al
1173 searchdir_iso:
1174 mov [ISOFlags],al
1175 TRACER 'S'
1176 call allocate_file ; Temporary file structure for directory
1177 jnz alloc_failure
1178 push es
1179 push ds
1180 pop es ; ES = DS
1181 mov si,CurDir
1182 cmp byte [di],'/' ; If filename begins with slash
1183 jne .not_rooted
1184 inc di ; Skip leading slash
1185 mov si,RootDir ; Reference root directory instead
1186 .not_rooted:
1187 mov eax,[si+dir_clust]
1188 mov [bx+file_left],eax
1189 mov eax,[si+dir_lba]
1190 mov [bx+file_sector],eax
1191 mov edx,[si+dir_len]
1192
1193 .look_for_slash:
1194 mov ax,di
1195 .scan:
1196 mov cl,[di]
1197 inc di
1198 and cl,cl
1199 jz .isfile
1200 cmp cl,'/'
1201 jne .scan
1202 mov [di-1],byte 0 ; Terminate at directory name
1203 mov cl,02h ; Search for directory
1204 xchg cl,[ISOFlags]
1205
1206 push di ; Save these...
1207 push cx
1208
1209 ; Create recursion stack frame...
1210 push word .resume ; Where to "return" to
1211 push es
1212 .isfile: xchg ax,di
1213
1214 .getsome:
1215 ; Get a chunk of the directory
1216 ; This relies on the fact that ISOLINUX doesn't change SI
1217 mov si,trackbuf
1218 TRACER 'g'
1219 pushad
1220 xchg bx,si
1221 mov cx,[BufSafe]
1222 call getfssec
1223 popad
1224
1225 .compare:
1226 movzx eax,byte [si] ; Length of directory entry
1227 cmp al,33
1228 jb .next_sector
1229 TRACER 'c'
1230 mov cl,[si+25]
1231 xor cl,[ISOFlags]
1232 test cl, byte 8Eh ; Unwanted file attributes!
1233 jnz .not_file
1234 pusha
1235 movzx cx,byte [si+32] ; File identifier length
1236 add si,byte 33 ; File identifier offset
1237 TRACER 'i'
1238 call iso_compare_names
1239 popa
1240 je .success
1241 .not_file:
1242 sub edx,eax ; Decrease bytes left
1243 jbe .failure
1244 add si,ax ; Advance pointer
1245
1246 .check_overrun:
1247 ; Did we finish the buffer?
1248 cmp si,trackbuf+trackbufsize
1249 jb .compare ; No, keep going
1250
1251 jmp short .getsome ; Get some more directory
1252
1253 .next_sector:
1254 ; Advance to the beginning of next sector
1255 lea ax,[si+SECTOR_SIZE-1]
1256 and ax,~(SECTOR_SIZE-1)
1257 sub ax,si
1258 jmp short .not_file ; We still need to do length checks
1259
1260 .failure: xor eax,eax ; ZF = 1
1261 mov [bx+file_sector],eax
1262 pop es
1263 ret
1264
1265 .success:
1266 mov eax,[si+2] ; Location of extent
1267 mov [bx+file_sector],eax
1268 mov eax,[si+10] ; Data length
1269 mov [bx+file_bytesleft],eax
1270 push eax
1271 add eax,SECTOR_SIZE-1
1272 shr eax,SECTOR_SHIFT
1273 mov [bx+file_left],eax
1274 pop eax
1275 and bx,bx ; ZF = 0
1276 mov si,bx
1277 pop es
1278 ret
1279
1280 .resume: ; We get here if we were only doing part of a lookup
1281 ; This relies on the fact that .success returns bx == si
1282 xchg edx,eax ; Directory length in edx
1283 pop cx ; Old ISOFlags
1284 pop di ; Next filename pointer
1285 mov byte [di-1], '/' ; Restore slash
1286 mov [ISOFlags],cl ; Restore the flags
1287 jz .failure ; Did we fail? If so fail for real!
1288 jmp .look_for_slash ; Otherwise, next level
1289
1290 ;
1291 ; allocate_file: Allocate a file structure
1292 ;
1293 ; If successful:
1294 ; ZF set
1295 ; BX = file pointer
1296 ; In unsuccessful:
1297 ; ZF clear
1298 ;
1299 allocate_file:
1300 TRACER 'a'
1301 push cx
1302 mov bx,Files
1303 mov cx,MAX_OPEN
1304 .check: cmp dword [bx], byte 0
1305 je .found
1306 add bx,open_file_t_size ; ZF = 0
1307 loop .check
1308 ; ZF = 0 if we fell out of the loop
1309 .found: pop cx
1310 ret
1311
1312 ;
1313 ; iso_compare_names:
1314 ; Compare the names DS:SI and DS:DI and report if they are
1315 ; equal from an ISO 9660 perspective. SI is the name from
1316 ; the filesystem; CX indicates its length, and ';' terminates.
1317 ; DI is expected to end with a null.
1318 ;
1319 ; Note: clobbers AX, CX, SI, DI; assumes DS == ES == base segment
1320 ;
1321
1322 iso_compare_names:
1323 ; First, terminate and canonicalize input filename
1324 push di
1325 mov di,ISOFileName
1326 .canon_loop: jcxz .canon_end
1327 lodsb
1328 dec cx
1329 cmp al,';'
1330 je .canon_end
1331 and al,al
1332 je .canon_end
1333 stosb
1334 cmp di,ISOFileNameEnd-1 ; Guard against buffer overrun
1335 jb .canon_loop
1336 .canon_end:
1337 cmp di,ISOFileName
1338 jbe .canon_done
1339 cmp byte [di-1],'.' ; Remove terminal dots
1340 jne .canon_done
1341 dec di
1342 jmp short .canon_end
1343 .canon_done:
1344 mov [di],byte 0 ; Null-terminate string
1345 pop di
1346 mov si,ISOFileName
1347 .compare:
1348 lodsb
1349 mov ah,[di]
1350 inc di
1351 and ax,ax
1352 jz .success ; End of string for both
1353 and al,al ; Is either one end of string?
1354 jz .failure ; If so, failure
1355 and ah,ah
1356 jz .failure
1357 or ax,2020h ; Convert to lower case
1358 cmp al,ah
1359 je .compare
1360 .failure: and ax,ax ; ZF = 0 (at least one will be nonzero)
1361 .success: ret
1362
1363 ;
1364 ; mangle_name: Mangle a filename pointed to by DS:SI into a buffer pointed
1365 ; to by ES:DI; ends on encountering any whitespace.
1366 ; DI is preserved.
1367 ;
1368 ; This verifies that a filename is < FILENAME_MAX characters,
1369 ; doesn't contain whitespace, zero-pads the output buffer,
1370 ; and removes trailing dots and redundant slashes,
1371 ; so "repe cmpsb" can do a compare, and the
1372 ; path-searching routine gets a bit of an easier job.
1373 ;
1374 mangle_name:
1375 push di
1376 push bx
1377 xor ax,ax
1378 mov cx,FILENAME_MAX-1
1379 mov bx,di
1380
1381 .mn_loop:
1382 lodsb
1383 cmp al,' ' ; If control or space, end
1384 jna .mn_end
1385 cmp al,ah ; Repeated slash?
1386 je .mn_skip
1387 xor ah,ah
1388 cmp al,'/'
1389 jne .mn_ok
1390 mov ah,al
1391 .mn_ok stosb
1392 .mn_skip: loop .mn_loop
1393 .mn_end:
1394 cmp bx,di ; At the beginning of the buffer?
1395 jbe .mn_zero
1396 cmp byte [es:di-1],'.' ; Terminal dot?
1397 je .mn_kill
1398 cmp byte [es:di-1],'/' ; Terminal slash?
1399 jne .mn_zero
1400 .mn_kill: dec di ; If so, remove it
1401 inc cx
1402 jmp short .mn_end
1403 .mn_zero:
1404 inc cx ; At least one null byte
1405 xor ax,ax ; Zero-fill name
1406 rep stosb
1407 pop bx
1408 pop di
1409 ret ; Done
1410
1411 ;
1412 ; unmangle_name: Does the opposite of mangle_name; converts a DOS-mangled
1413 ; filename to the conventional representation. This is needed
1414 ; for the BOOT_IMAGE= parameter for the kernel.
1415 ;
1416 ; DS:SI -> input mangled file name
1417 ; ES:DI -> output buffer
1418 ;
1419 ; On return, DI points to the first byte after the output name,
1420 ; which is set to a null byte.
1421 ;
1422 unmangle_name: call strcpy
1423 dec di ; Point to final null byte
1424 ret
1425
1426 ;
1427 ; getfssec: Get multiple clusters from a file, given the file pointer.
1428 ;
1429 ; On entry:
1430 ; ES:BX -> Buffer
1431 ; SI -> File pointer
1432 ; CX -> Cluster count
1433 ; On exit:
1434 ; SI -> File pointer (or 0 on EOF)
1435 ; CF = 1 -> Hit EOF
1436 ; ECX -> Bytes actually read
1437 ;
1438 getfssec:
1439 TRACER 'F'
1440
1441 push ds
1442 push cs
1443 pop ds ; DS <- CS
1444
1445 movzx ecx,cx
1446 cmp ecx,[si+file_left]
1447 jna .ok_size
1448 mov ecx,[si+file_left]
1449
1450 .ok_size:
1451 mov bp,cx
1452 push cx
1453 push si
1454 mov eax,[si+file_sector]
1455 TRACER 'l'
1456 call getlinsec
1457 xor ecx,ecx
1458 pop si
1459 pop cx
1460
1461 add [si+file_sector],ecx
1462 sub [si+file_left],ecx
1463 ja .not_eof ; CF = 0
1464 stc
1465
1466 .not_eof:
1467 pushf
1468 shl ecx,SECTOR_SHIFT ; Convert to bytes
1469 cmp ecx,[si+file_bytesleft]
1470 jb .not_all
1471 mov ecx,[si+file_bytesleft]
1472 .not_all: sub [si+file_bytesleft],ecx
1473 popf
1474 jnc .ret
1475 push eax
1476 xor eax,eax
1477 mov [si+file_sector],eax ; Unused
1478 mov si,ax
1479 pop eax
1480 stc
1481 .ret:
1482 pop ds
1483 TRACER 'f'
1484 ret
1485
1486 ; -----------------------------------------------------------------------------
1487 ; Common modules
1488 ; -----------------------------------------------------------------------------
1489
1490 %include "getc.inc" ; getc et al
1491 %include "conio.inc" ; Console I/O
1492 %include "configinit.inc" ; Initialize configuration
1493 %include "parseconfig.inc" ; High-level config file handling
1494 %include "parsecmd.inc" ; Low-level config file handling
1495 %include "bcopy32.inc" ; 32-bit bcopy
1496 %include "loadhigh.inc" ; Load a file into high memory
1497 %include "font.inc" ; VGA font stuff
1498 %include "graphics.inc" ; VGA graphics
1499 %include "highmem.inc" ; High memory sizing
1500 %include "strcpy.inc" ; strcpy()
1501 %include "rawcon.inc" ; Console I/O w/o using the console functions
1502 %include "adv.inc" ; Auxillary Data Vector
1503
1504 ; -----------------------------------------------------------------------------
1505 ; Begin data section
1506 ; -----------------------------------------------------------------------------
1507
1508 section .data
1509
1510 localboot_msg db 'Booting from local disk...', CR, LF, 0
1511 default_str db 'default', 0
1512 default_len equ ($-default_str)
1513 boot_dir db '/boot' ; /boot/isolinux
1514 isolinux_dir db '/isolinux', 0
1515 config_name db 'isolinux.cfg', 0
1516 err_disk_image db 'Cannot load disk image (invalid file)?', CR, LF, 0
1517
1518 %ifdef DEBUG_MESSAGES
1519 dbg_rootdir_msg db 'Root directory at LBA = ', 0
1520 dbg_isodir_msg db 'isolinux directory at LBA = ', 0
1521 dbg_config_msg db 'About to load config file...', CR, LF, 0
1522 dbg_configok_msg db 'Configuration file opened...', CR, LF, 0
1523 %endif
1524 ;
1525 ; Command line options we'd like to take a look at
1526 ;
1527 ; mem= and vga= are handled as normal 32-bit integer values
1528 initrd_cmd db 'initrd='
1529 initrd_cmd_len equ 7
1530
1531 ;
1532 ; Config file keyword table
1533 ;
1534 %include "keywords.inc"
1535
1536 ;
1537 ; Extensions to search for (in *forward* order).
1538 ;
1539 align 4, db 0
1540 exten_table: db '.cbt' ; COMBOOT (specific)
1541 db '.img' ; Disk image
1542 db '.bin' ; CD boot sector
1543 db '.com' ; COMBOOT (same as DOS)
1544 db '.c32' ; COM32
1545 exten_table_end:
1546 dd 0, 0 ; Need 8 null bytes here
1547
1548 ;
1549 ; Floppy image table
1550 ;
1551 align 4, db 0
1552 img_table_count equ 3
1553 img_table:
1554 dd 1200*1024 ; 1200K floppy
1555 db 1 ; Emulation type
1556 db 80-1 ; Max cylinder
1557 db 15 ; Max sector
1558 db 2-1 ; Max head
1559
1560 dd 1440*1024 ; 1440K floppy
1561 db 2 ; Emulation type
1562 db 80-1 ; Max cylinder
1563 db 18 ; Max sector
1564 db 2-1 ; Max head
1565
1566 dd 2880*1024 ; 2880K floppy
1567 db 3 ; Emulation type
1568 db 80-1 ; Max cylinder
1569 db 36 ; Max sector
1570 db 2-1 ; Max head
1571
1572 ;
1573 ; Misc initialized (data) variables
1574 ;
1575
1576 ;
1577 ; Variables that are uninitialized in SYSLINUX but initialized here
1578 ;
1579 ; **** ISOLINUX:: We may have to make this flexible, based on what the
1580 ; **** BIOS expects our "sector size" to be.
1581 ;
1582 alignb 4, db 0
1583 BufSafe dw trackbufsize/SECTOR_SIZE ; Clusters we can load into trackbuf
1584 BufSafeBytes dw trackbufsize ; = how many bytes?
1585 %ifndef DEPEND
1586 %if ( trackbufsize % SECTOR_SIZE ) != 0
1587 %error trackbufsize must be a multiple of SECTOR_SIZE
1588 %endif
1589 %endif
The Syslinux boot loader collection