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Adding .24 support for olpc
[openwrt.git] / target / linux / olpc / files-2.6.23 / arch / i386 / boot / setup.S
1 /*
2 * setup.S Copyright (C) 1991, 1992 Linus Torvalds
3 *
4 * setup.s is responsible for getting the system data from the BIOS,
5 * and putting them into the appropriate places in system memory.
6 * both setup.s and system has been loaded by the bootblock.
7 *
8 * This code asks the bios for memory/disk/other parameters, and
9 * puts them in a "safe" place: 0x90000-0x901FF, ie where the
10 * boot-block used to be. It is then up to the protected mode
11 * system to read them from there before the area is overwritten
12 * for buffer-blocks.
13 *
14 * Move PS/2 aux init code to psaux.c
15 * (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
16 *
17 * some changes and additional features by Christoph Niemann,
18 * March 1993/June 1994 (Christoph.Niemann@linux.org)
19 *
20 * add APM BIOS checking by Stephen Rothwell, May 1994
21 * (sfr@canb.auug.org.au)
22 *
23 * High load stuff, initrd support and position independency
24 * by Hans Lermen & Werner Almesberger, February 1996
25 * <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
26 *
27 * Video handling moved to video.S by Martin Mares, March 1996
28 * <mj@k332.feld.cvut.cz>
29 *
30 * Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
31 * parsons) to avoid loadlin confusion, July 1997
32 *
33 * Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
34 * <stiker@northlink.com>
35 *
36 * Fix to work around buggy BIOSes which don't use carry bit correctly
37 * and/or report extended memory in CX/DX for e801h memory size detection
38 * call. As a result the kernel got wrong figures. The int15/e801h docs
39 * from Ralf Brown interrupt list seem to indicate AX/BX should be used
40 * anyway. So to avoid breaking many machines (presumably there was a reason
41 * to orginally use CX/DX instead of AX/BX), we do a kludge to see
42 * if CX/DX have been changed in the e801 call and if so use AX/BX .
43 * Michael Miller, April 2001 <michaelm@mjmm.org>
44 *
45 * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
46 * by Robert Schwebel, December 2001 <robert@schwebel.de>
47 */
48
49 #include <asm/segment.h>
50 #include <linux/utsrelease.h>
51 #include <linux/compile.h>
52 #include <asm/boot.h>
53 #include <asm/e820.h>
54 #include <asm/page.h>
55 #include <asm/setup.h>
56
57 /* Signature words to ensure LILO loaded us right */
58 #define SIG1 0xAA55
59 #define SIG2 0x5A5A
60
61 INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way
62 SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536).
63 SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment
64 # ... and the former contents of CS
65
66 DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020
67
68 .code16
69 .globl begtext, begdata, begbss, endtext, enddata, endbss
70
71 .text
72 begtext:
73 .data
74 begdata:
75 .bss
76 begbss:
77 .text
78
79 start:
80 jmp trampoline
81
82 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
83
84 .ascii "HdrS" # header signature
85 .word 0x0206 # header version number (>= 0x0105)
86 # or else old loadlin-1.5 will fail)
87 realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
88 start_sys_seg: .word SYSSEG
89 .word kernel_version # pointing to kernel version string
90 # above section of header is compatible
91 # with loadlin-1.5 (header v1.5). Don't
92 # change it.
93
94 type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
95 # Bootlin, SYSLX, bootsect...)
96 # See Documentation/i386/boot.txt for
97 # assigned ids
98
99 # flags, unused bits must be zero (RFU) bit within loadflags
100 loadflags:
101 LOADED_HIGH = 1 # If set, the kernel is loaded high
102 CAN_USE_HEAP = 0x80 # If set, the loader also has set
103 # heap_end_ptr to tell how much
104 # space behind setup.S can be used for
105 # heap purposes.
106 # Only the loader knows what is free
107 #ifndef __BIG_KERNEL__
108 .byte 0
109 #else
110 .byte LOADED_HIGH
111 #endif
112
113 setup_move_size: .word 0x8000 # size to move, when setup is not
114 # loaded at 0x90000. We will move setup
115 # to 0x90000 then just before jumping
116 # into the kernel. However, only the
117 # loader knows how much data behind
118 # us also needs to be loaded.
119
120 code32_start: # here loaders can put a different
121 # start address for 32-bit code.
122 #ifndef __BIG_KERNEL__
123 .long 0x1000 # 0x1000 = default for zImage
124 #else
125 .long 0x100000 # 0x100000 = default for big kernel
126 #endif
127
128 ramdisk_image: .long 0 # address of loaded ramdisk image
129 # Here the loader puts the 32-bit
130 # address where it loaded the image.
131 # This only will be read by the kernel.
132
133 ramdisk_size: .long 0 # its size in bytes
134
135 bootsect_kludge:
136 .long 0 # obsolete
137
138 heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later)
139 # space from here (exclusive) down to
140 # end of setup code can be used by setup
141 # for local heap purposes.
142
143 pad1: .word 0
144 cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
145 # If nonzero, a 32-bit pointer
146 # to the kernel command line.
147 # The command line should be
148 # located between the start of
149 # setup and the end of low
150 # memory (0xa0000), or it may
151 # get overwritten before it
152 # gets read. If this field is
153 # used, there is no longer
154 # anything magical about the
155 # 0x90000 segment; the setup
156 # can be located anywhere in
157 # low memory 0x10000 or higher.
158
159 ramdisk_max: .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
160 # (Header version 0x0203 or later)
161 # The highest safe address for
162 # the contents of an initrd
163
164 kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
165 #required for protected mode
166 #kernel
167 #ifdef CONFIG_RELOCATABLE
168 relocatable_kernel: .byte 1
169 #else
170 relocatable_kernel: .byte 0
171 #endif
172 pad2: .byte 0
173 pad3: .word 0
174
175 cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
176 #added with boot protocol
177 #version 2.06
178
179 trampoline: call start_of_setup
180 .align 16
181 # The offset at this point is 0x240
182 .space (0xeff-0x240+1) # E820 & EDD space (ending at 0xeff)
183 # End of setup header #####################################################
184
185 start_of_setup:
186 # Bootlin depends on this being done early
187 movw $0x01500, %ax
188 movb $0x81, %dl
189 int $0x13
190
191 #ifdef SAFE_RESET_DISK_CONTROLLER
192 # Reset the disk controller.
193 movw $0x0000, %ax
194 movb $0x80, %dl
195 int $0x13
196 #endif
197
198 # Set %ds = %cs, we know that SETUPSEG = %cs at this point
199 movw %cs, %ax # aka SETUPSEG
200 movw %ax, %ds
201 # Check signature at end of setup
202 cmpw $SIG1, setup_sig1
203 jne bad_sig
204
205 cmpw $SIG2, setup_sig2
206 jne bad_sig
207
208 jmp good_sig1
209
210 # Routine to print asciiz string at ds:si
211 prtstr:
212 lodsb
213 andb %al, %al
214 jz fin
215
216 call prtchr
217 jmp prtstr
218
219 fin: ret
220
221 # Space printing
222 prtsp2: call prtspc # Print double space
223 prtspc: movb $0x20, %al # Print single space (note: fall-thru)
224
225 # Part of above routine, this one just prints ascii al
226 prtchr: pushw %ax
227 pushw %cx
228 movw $7,%bx
229 movw $0x01, %cx
230 movb $0x0e, %ah
231 int $0x10
232 popw %cx
233 popw %ax
234 ret
235
236 beep: movb $0x07, %al
237 jmp prtchr
238
239 no_sig_mess: .string "No setup signature found ..."
240
241 good_sig1:
242 jmp good_sig
243
244 # We now have to find the rest of the setup code/data
245 bad_sig:
246 movw %cs, %ax # SETUPSEG
247 subw $DELTA_INITSEG, %ax # INITSEG
248 movw %ax, %ds
249 xorb %bh, %bh
250 movb (497), %bl # get setup sect from bootsect
251 subw $4, %bx # LILO loads 4 sectors of setup
252 shlw $8, %bx # convert to words (1sect=2^8 words)
253 movw %bx, %cx
254 shrw $3, %bx # convert to segment
255 addw $SYSSEG, %bx
256 movw %bx, %cs:start_sys_seg
257 # Move rest of setup code/data to here
258 movw $2048, %di # four sectors loaded by LILO
259 subw %si, %si
260 pushw %cs
261 popw %es
262 movw $SYSSEG, %ax
263 movw %ax, %ds
264 rep
265 movsw
266 movw %cs, %ax # aka SETUPSEG
267 movw %ax, %ds
268 cmpw $SIG1, setup_sig1
269 jne no_sig
270
271 cmpw $SIG2, setup_sig2
272 jne no_sig
273
274 jmp good_sig
275
276 no_sig:
277 lea no_sig_mess, %si
278 call prtstr
279
280 no_sig_loop:
281 hlt
282 jmp no_sig_loop
283
284 good_sig:
285 movw %cs, %ax # aka SETUPSEG
286 subw $DELTA_INITSEG, %ax # aka INITSEG
287 movw %ax, %ds
288 # Check if an old loader tries to load a big-kernel
289 testb $LOADED_HIGH, %cs:loadflags # Do we have a big kernel?
290 jz loader_ok # No, no danger for old loaders.
291
292 cmpb $0, %cs:type_of_loader # Do we have a loader that
293 # can deal with us?
294 jnz loader_ok # Yes, continue.
295
296 pushw %cs # No, we have an old loader,
297 popw %ds # die.
298 lea loader_panic_mess, %si
299 call prtstr
300
301 jmp no_sig_loop
302
303 loader_panic_mess: .string "Wrong loader, giving up..."
304
305 # check minimum cpuid
306 # we do this here because it is the last place we can actually
307 # show a user visible error message. Later the video modus
308 # might be already messed up.
309 loader_ok:
310 call verify_cpu
311 testl %eax,%eax
312 jz cpu_ok
313 movw %cs,%ax # aka SETUPSEG
314 movw %ax,%ds
315 lea cpu_panic_mess,%si
316 call prtstr
317 1: jmp 1b
318
319 cpu_panic_mess:
320 .asciz "PANIC: CPU too old for this kernel."
321
322 #include "../kernel/verify_cpu.S"
323
324 cpu_ok:
325 # Get memory size (extended mem, kB)
326
327 xorl %eax, %eax
328 movl %eax, (0x1e0)
329 #ifndef STANDARD_MEMORY_BIOS_CALL
330 movb %al, (E820NR)
331 # Try three different memory detection schemes. First, try
332 # e820h, which lets us assemble a memory map, then try e801h,
333 # which returns a 32-bit memory size, and finally 88h, which
334 # returns 0-64m
335
336 # method E820H:
337 # the memory map from hell. e820h returns memory classified into
338 # a whole bunch of different types, and allows memory holes and
339 # everything. We scan through this memory map and build a list
340 # of the first 32 memory areas, which we return at [E820MAP].
341 # This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.
342
343 #define SMAP 0x534d4150
344
345 meme820:
346 xorl %ebx, %ebx # continuation counter
347 movw $E820MAP, %di # point into the whitelist
348 # so we can have the bios
349 # directly write into it.
350
351 jmpe820:
352 movl $0x0000e820, %eax # e820, upper word zeroed
353 movl $SMAP, %edx # ascii 'SMAP'
354 movl $20, %ecx # size of the e820rec
355 pushw %ds # data record.
356 popw %es
357 int $0x15 # make the call
358 jc bail820 # fall to e801 if it fails
359
360 cmpl $SMAP, %eax # check the return is `SMAP'
361 jne bail820 # fall to e801 if it fails
362
363 # cmpl $1, 16(%di) # is this usable memory?
364 # jne again820
365
366 # If this is usable memory, we save it by simply advancing %di by
367 # sizeof(e820rec).
368 #
369 good820:
370 movb (E820NR), %al # up to 128 entries
371 cmpb $E820MAX, %al
372 jae bail820
373
374 incb (E820NR)
375 movw %di, %ax
376 addw $20, %ax
377 movw %ax, %di
378 again820:
379 cmpl $0, %ebx # check to see if
380 jne jmpe820 # %ebx is set to EOF
381 bail820:
382
383
384 # method E801H:
385 # memory size is in 1k chunksizes, to avoid confusing loadlin.
386 # we store the 0xe801 memory size in a completely different place,
387 # because it will most likely be longer than 16 bits.
388 # (use 1e0 because that's what Larry Augustine uses in his
389 # alternative new memory detection scheme, and it's sensible
390 # to write everything into the same place.)
391
392 meme801:
393 stc # fix to work around buggy
394 xorw %cx,%cx # BIOSes which don't clear/set
395 xorw %dx,%dx # carry on pass/error of
396 # e801h memory size call
397 # or merely pass cx,dx though
398 # without changing them.
399 movw $0xe801, %ax
400 int $0x15
401 jc mem88
402
403 cmpw $0x0, %cx # Kludge to handle BIOSes
404 jne e801usecxdx # which report their extended
405 cmpw $0x0, %dx # memory in AX/BX rather than
406 jne e801usecxdx # CX/DX. The spec I have read
407 movw %ax, %cx # seems to indicate AX/BX
408 movw %bx, %dx # are more reasonable anyway...
409
410 e801usecxdx:
411 andl $0xffff, %edx # clear sign extend
412 shll $6, %edx # and go from 64k to 1k chunks
413 movl %edx, (0x1e0) # store extended memory size
414 andl $0xffff, %ecx # clear sign extend
415 addl %ecx, (0x1e0) # and add lower memory into
416 # total size.
417
418 # Ye Olde Traditional Methode. Returns the memory size (up to 16mb or
419 # 64mb, depending on the bios) in ax.
420 mem88:
421
422 #endif
423 movb $0x88, %ah
424 int $0x15
425 movw %ax, (2)
426
427 # Set the keyboard repeat rate to the max
428 movw $0x0305, %ax
429 xorw %bx, %bx
430 int $0x16
431
432 #ifndef CONFIG_VGA_NOPROBE
433
434 # Check for video adapter and its parameters and allow the
435 # user to browse video modes.
436 call video # NOTE: we need %ds pointing
437 # to bootsector
438 #endif
439
440 # Get hd0 data...
441 xorw %ax, %ax
442 movw %ax, %ds
443 ldsw (4 * 0x41), %si
444 movw %cs, %ax # aka SETUPSEG
445 subw $DELTA_INITSEG, %ax # aka INITSEG
446 pushw %ax
447 movw %ax, %es
448 movw $0x0080, %di
449 movw $0x10, %cx
450 pushw %cx
451 cld
452 rep
453 movsb
454 # Get hd1 data...
455 xorw %ax, %ax
456 movw %ax, %ds
457 ldsw (4 * 0x46), %si
458 popw %cx
459 popw %es
460 movw $0x0090, %di
461 rep
462 movsb
463 # Check that there IS a hd1 :-)
464 movw $0x01500, %ax
465 movb $0x81, %dl
466 int $0x13
467 jc no_disk1
468
469 cmpb $3, %ah
470 je is_disk1
471
472 no_disk1:
473 movw %cs, %ax # aka SETUPSEG
474 subw $DELTA_INITSEG, %ax # aka INITSEG
475 movw %ax, %es
476 movw $0x0090, %di
477 movw $0x10, %cx
478 xorw %ax, %ax
479 cld
480 rep
481 stosb
482 is_disk1:
483 # check for Micro Channel (MCA) bus
484 movw %cs, %ax # aka SETUPSEG
485 subw $DELTA_INITSEG, %ax # aka INITSEG
486 movw %ax, %ds
487 xorw %ax, %ax
488 movw %ax, (0xa0) # set table length to 0
489 movb $0xc0, %ah
490 stc
491 int $0x15 # moves feature table to es:bx
492 jc no_mca
493
494 pushw %ds
495 movw %es, %ax
496 movw %ax, %ds
497 movw %cs, %ax # aka SETUPSEG
498 subw $DELTA_INITSEG, %ax # aka INITSEG
499 movw %ax, %es
500 movw %bx, %si
501 movw $0xa0, %di
502 movw (%si), %cx
503 addw $2, %cx # table length is a short
504 cmpw $0x10, %cx
505 jc sysdesc_ok
506
507 movw $0x10, %cx # we keep only first 16 bytes
508 sysdesc_ok:
509 rep
510 movsb
511 popw %ds
512 no_mca:
513 #ifdef CONFIG_X86_VOYAGER
514 movb $0xff, 0x40 # flag on config found
515 movb $0xc0, %al
516 mov $0xff, %ah
517 int $0x15 # put voyager config info at es:di
518 jc no_voyager
519 movw $0x40, %si # place voyager info in apm table
520 cld
521 movw $7, %cx
522 voyager_rep:
523 movb %es:(%di), %al
524 movb %al,(%si)
525 incw %di
526 incw %si
527 decw %cx
528 jnz voyager_rep
529 no_voyager:
530 #endif
531 # Check for PS/2 pointing device
532 movw %cs, %ax # aka SETUPSEG
533 subw $DELTA_INITSEG, %ax # aka INITSEG
534 movw %ax, %ds
535 movb $0, (0x1ff) # default is no pointing device
536 int $0x11 # int 0x11: equipment list
537 testb $0x04, %al # check if mouse installed
538 jz no_psmouse
539
540 movb $0xAA, (0x1ff) # device present
541 no_psmouse:
542
543 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
544 movl $0x0000E980, %eax # IST Support
545 movl $0x47534943, %edx # Request value
546 int $0x15
547
548 movl %eax, (96)
549 movl %ebx, (100)
550 movl %ecx, (104)
551 movl %edx, (108)
552 #endif
553
554 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
555 # Then check for an APM BIOS...
556 # %ds points to the bootsector
557 movw $0, 0x40 # version = 0 means no APM BIOS
558 movw $0x05300, %ax # APM BIOS installation check
559 xorw %bx, %bx
560 int $0x15
561 jc done_apm_bios # Nope, no APM BIOS
562
563 cmpw $0x0504d, %bx # Check for "PM" signature
564 jne done_apm_bios # No signature, no APM BIOS
565
566 andw $0x02, %cx # Is 32 bit supported?
567 je done_apm_bios # No 32-bit, no (good) APM BIOS
568
569 movw $0x05304, %ax # Disconnect first just in case
570 xorw %bx, %bx
571 int $0x15 # ignore return code
572 movw $0x05303, %ax # 32 bit connect
573 xorl %ebx, %ebx
574 xorw %cx, %cx # paranoia :-)
575 xorw %dx, %dx # ...
576 xorl %esi, %esi # ...
577 xorw %di, %di # ...
578 int $0x15
579 jc no_32_apm_bios # Ack, error.
580
581 movw %ax, (66) # BIOS code segment
582 movl %ebx, (68) # BIOS entry point offset
583 movw %cx, (72) # BIOS 16 bit code segment
584 movw %dx, (74) # BIOS data segment
585 movl %esi, (78) # BIOS code segment lengths
586 movw %di, (82) # BIOS data segment length
587 # Redo the installation check as the 32 bit connect
588 # modifies the flags returned on some BIOSs
589 movw $0x05300, %ax # APM BIOS installation check
590 xorw %bx, %bx
591 xorw %cx, %cx # paranoia
592 int $0x15
593 jc apm_disconnect # error -> shouldn't happen
594
595 cmpw $0x0504d, %bx # check for "PM" signature
596 jne apm_disconnect # no sig -> shouldn't happen
597
598 movw %ax, (64) # record the APM BIOS version
599 movw %cx, (76) # and flags
600 jmp done_apm_bios
601
602 apm_disconnect: # Tidy up
603 movw $0x05304, %ax # Disconnect
604 xorw %bx, %bx
605 int $0x15 # ignore return code
606
607 jmp done_apm_bios
608
609 no_32_apm_bios:
610 andw $0xfffd, (76) # remove 32 bit support bit
611 done_apm_bios:
612 #endif
613
614 #include "edd.S"
615
616 # Now we want to move to protected mode ...
617 cmpw $0, %cs:realmode_swtch
618 jz rmodeswtch_normal
619
620 lcall *%cs:realmode_swtch
621
622 jmp rmodeswtch_end
623
624 rmodeswtch_normal:
625 pushw %cs
626 call default_switch
627
628 rmodeswtch_end:
629 # Now we move the system to its rightful place ... but we check if we have a
630 # big-kernel. In that case we *must* not move it ...
631 testb $LOADED_HIGH, %cs:loadflags
632 jz do_move0 # .. then we have a normal low
633 # loaded zImage
634 # .. or else we have a high
635 # loaded bzImage
636 jmp end_move # ... and we skip moving
637
638 do_move0:
639 movw $0x100, %ax # start of destination segment
640 movw %cs, %bp # aka SETUPSEG
641 subw $DELTA_INITSEG, %bp # aka INITSEG
642 movw %cs:start_sys_seg, %bx # start of source segment
643 cld
644 do_move:
645 movw %ax, %es # destination segment
646 incb %ah # instead of add ax,#0x100
647 movw %bx, %ds # source segment
648 addw $0x100, %bx
649 subw %di, %di
650 subw %si, %si
651 movw $0x800, %cx
652 rep
653 movsw
654 cmpw %bp, %bx # assume start_sys_seg > 0x200,
655 # so we will perhaps read one
656 # page more than needed, but
657 # never overwrite INITSEG
658 # because destination is a
659 # minimum one page below source
660 jb do_move
661
662 end_move:
663 # then we load the segment descriptors
664 movw %cs, %ax # aka SETUPSEG
665 movw %ax, %ds
666
667 # Check whether we need to be downward compatible with version <=201
668 cmpl $0, cmd_line_ptr
669 jne end_move_self # loader uses version >=202 features
670 cmpb $0x20, type_of_loader
671 je end_move_self # bootsect loader, we know of it
672
673 # Boot loader doesnt support boot protocol version 2.02.
674 # If we have our code not at 0x90000, we need to move it there now.
675 # We also then need to move the params behind it (commandline)
676 # Because we would overwrite the code on the current IP, we move
677 # it in two steps, jumping high after the first one.
678 movw %cs, %ax
679 cmpw $SETUPSEG, %ax
680 je end_move_self
681
682 cli # make sure we really have
683 # interrupts disabled !
684 # because after this the stack
685 # should not be used
686 subw $DELTA_INITSEG, %ax # aka INITSEG
687 movw %ss, %dx
688 cmpw %ax, %dx
689 jb move_self_1
690
691 addw $INITSEG, %dx
692 subw %ax, %dx # this will go into %ss after
693 # the move
694 move_self_1:
695 movw %ax, %ds
696 movw $INITSEG, %ax # real INITSEG
697 movw %ax, %es
698 movw %cs:setup_move_size, %cx
699 std # we have to move up, so we use
700 # direction down because the
701 # areas may overlap
702 movw %cx, %di
703 decw %di
704 movw %di, %si
705 subw $move_self_here+0x200, %cx
706 rep
707 movsb
708 ljmp $SETUPSEG, $move_self_here
709
710 move_self_here:
711 movw $move_self_here+0x200, %cx
712 rep
713 movsb
714 movw $SETUPSEG, %ax
715 movw %ax, %ds
716 movw %dx, %ss
717 end_move_self: # now we are at the right place
718
719 #
720 # Enable A20. This is at the very best an annoying procedure.
721 # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
722 # AMD Elan bug fix by Robert Schwebel.
723 #
724
725 #if defined(CONFIG_X86_ELAN)
726 movb $0x02, %al # alternate A20 gate
727 outb %al, $0x92 # this works on SC410/SC520
728 a20_elan_wait:
729 call a20_test
730 jz a20_elan_wait
731 jmp a20_done
732 #endif
733
734
735 A20_TEST_LOOPS = 32 # Iterations per wait
736 A20_ENABLE_LOOPS = 255 # Total loops to try
737
738
739 #ifndef CONFIG_X86_VOYAGER
740 a20_try_loop:
741
742 # First, see if we are on a system with no A20 gate.
743 a20_none:
744 call a20_test
745 jnz a20_done
746
747 # Next, try the BIOS (INT 0x15, AX=0x2401)
748 a20_bios:
749 movw $0x2401, %ax
750 pushfl # Be paranoid about flags
751 int $0x15
752 popfl
753
754 call a20_test
755 jnz a20_done
756
757 # Try enabling A20 through the keyboard controller
758 #endif /* CONFIG_X86_VOYAGER */
759 a20_kbc:
760 call empty_8042
761
762 #ifndef CONFIG_X86_VOYAGER
763 call a20_test # Just in case the BIOS worked
764 jnz a20_done # but had a delayed reaction.
765 #endif
766
767 movb $0xD1, %al # command write
768 outb %al, $0x64
769 call empty_8042
770
771 movb $0xDF, %al # A20 on
772 outb %al, $0x60
773 call empty_8042
774
775 #ifndef CONFIG_X86_VOYAGER
776 # Wait until a20 really *is* enabled; it can take a fair amount of
777 # time on certain systems; Toshiba Tecras are known to have this
778 # problem.
779 a20_kbc_wait:
780 xorw %cx, %cx
781 a20_kbc_wait_loop:
782 call a20_test
783 jnz a20_done
784 loop a20_kbc_wait_loop
785
786 # Final attempt: use "configuration port A"
787 a20_fast:
788 inb $0x92, %al # Configuration Port A
789 orb $0x02, %al # "fast A20" version
790 andb $0xFE, %al # don't accidentally reset
791 outb %al, $0x92
792
793 # Wait for configuration port A to take effect
794 a20_fast_wait:
795 xorw %cx, %cx
796 a20_fast_wait_loop:
797 call a20_test
798 jnz a20_done
799 loop a20_fast_wait_loop
800
801 # A20 is still not responding. Try frobbing it again.
802 #
803 decb (a20_tries)
804 jnz a20_try_loop
805
806 movw $a20_err_msg, %si
807 call prtstr
808
809 a20_die:
810 hlt
811 jmp a20_die
812
813 a20_tries:
814 .byte A20_ENABLE_LOOPS
815
816 a20_err_msg:
817 .ascii "linux: fatal error: A20 gate not responding!"
818 .byte 13, 10, 0
819
820 # If we get here, all is good
821 a20_done:
822
823 #endif /* CONFIG_X86_VOYAGER */
824 # set up gdt and idt and 32bit start address
825 lidt idt_48 # load idt with 0,0
826 xorl %eax, %eax # Compute gdt_base
827 movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
828 shll $4, %eax
829 addl %eax, code32
830 addl $gdt, %eax
831 movl %eax, (gdt_48+2)
832 lgdt gdt_48 # load gdt with whatever is
833 # appropriate
834
835 # make sure any possible coprocessor is properly reset..
836 xorw %ax, %ax
837 outb %al, $0xf0
838 call delay
839
840 outb %al, $0xf1
841 call delay
842
843 # well, that went ok, I hope. Now we mask all interrupts - the rest
844 # is done in init_IRQ().
845 movb $0xFF, %al # mask all interrupts for now
846 outb %al, $0xA1
847 call delay
848
849 movb $0xFB, %al # mask all irq's but irq2 which
850 outb %al, $0x21 # is cascaded
851
852 # Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
853 # need no steenking BIOS anyway (except for the initial loading :-).
854 # The BIOS-routine wants lots of unnecessary data, and it's less
855 # "interesting" anyway. This is how REAL programmers do it.
856 #
857 # Well, now's the time to actually move into protected mode. To make
858 # things as simple as possible, we do no register set-up or anything,
859 # we let the gnu-compiled 32-bit programs do that. We just jump to
860 # absolute address 0x1000 (or the loader supplied one),
861 # in 32-bit protected mode.
862 #
863 # Note that the short jump isn't strictly needed, although there are
864 # reasons why it might be a good idea. It won't hurt in any case.
865 movw $1, %ax # protected mode (PE) bit
866 lmsw %ax # This is it!
867 jmp flush_instr
868
869 flush_instr:
870 xorw %bx, %bx # Flag to indicate a boot
871 xorl %esi, %esi # Pointer to real-mode code
872 movw %cs, %si
873 subw $DELTA_INITSEG, %si
874 shll $4, %esi # Convert to 32-bit pointer
875
876 # jump to startup_32 in arch/i386/boot/compressed/head.S
877 #
878 # NOTE: For high loaded big kernels we need a
879 # jmpi 0x100000,__BOOT_CS
880 #
881 # but we yet haven't reloaded the CS register, so the default size
882 # of the target offset still is 16 bit.
883 # However, using an operand prefix (0x66), the CPU will properly
884 # take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
885 # Manual, Mixing 16-bit and 32-bit code, page 16-6)
886
887 .byte 0x66, 0xea # prefix + jmpi-opcode
888 code32: .long startup_32 # will be set to %cs+startup_32
889 .word __BOOT_CS
890 .code32
891 startup_32:
892 movl $(__BOOT_DS), %eax
893 movl %eax, %ds
894 movl %eax, %es
895 movl %eax, %fs
896 movl %eax, %gs
897 movl %eax, %ss
898
899 xorl %eax, %eax
900 1: incl %eax # check that A20 really IS enabled
901 movl %eax, 0x00000000 # loop forever if it isn't
902 cmpl %eax, 0x00100000
903 je 1b
904
905 # Jump to the 32bit entry point
906 jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi)
907 .code16
908
909 # Here's a bunch of information about your current kernel..
910 kernel_version: .ascii UTS_RELEASE
911 .ascii " ("
912 .ascii LINUX_COMPILE_BY
913 .ascii "@"
914 .ascii LINUX_COMPILE_HOST
915 .ascii ") "
916 .ascii UTS_VERSION
917 .byte 0
918
919 # This is the default real mode switch routine.
920 # to be called just before protected mode transition
921 default_switch:
922 cli # no interrupts allowed !
923 movb $0x80, %al # disable NMI for bootup
924 # sequence
925 outb %al, $0x70
926 lret
927
928
929 #ifndef CONFIG_X86_VOYAGER
930 # This routine tests whether or not A20 is enabled. If so, it
931 # exits with zf = 0.
932 #
933 # The memory address used, 0x200, is the int $0x80 vector, which
934 # should be safe.
935
936 A20_TEST_ADDR = 4*0x80
937
938 a20_test:
939 pushw %cx
940 pushw %ax
941 xorw %cx, %cx
942 movw %cx, %fs # Low memory
943 decw %cx
944 movw %cx, %gs # High memory area
945 movw $A20_TEST_LOOPS, %cx
946 movw %fs:(A20_TEST_ADDR), %ax
947 pushw %ax
948 a20_test_wait:
949 incw %ax
950 movw %ax, %fs:(A20_TEST_ADDR)
951 call delay # Serialize and make delay constant
952 cmpw %gs:(A20_TEST_ADDR+0x10), %ax
953 loope a20_test_wait
954
955 popw %fs:(A20_TEST_ADDR)
956 popw %ax
957 popw %cx
958 ret
959
960 #endif /* CONFIG_X86_VOYAGER */
961
962 # This routine checks that the keyboard command queue is empty
963 # (after emptying the output buffers)
964 #
965 # Some machines have delusions that the keyboard buffer is always full
966 # with no keyboard attached...
967 #
968 # If there is no keyboard controller, we will usually get 0xff
969 # to all the reads. With each IO taking a microsecond and
970 # a timeout of 100,000 iterations, this can take about half a
971 # second ("delay" == outb to port 0x80). That should be ok,
972 # and should also be plenty of time for a real keyboard controller
973 # to empty.
974 #
975
976 empty_8042:
977 pushl %ecx
978 movl $100000, %ecx
979
980 empty_8042_loop:
981 decl %ecx
982 jz empty_8042_end_loop
983
984 call delay
985
986 inb $0x64, %al # 8042 status port
987 testb $1, %al # output buffer?
988 jz no_output
989
990 call delay
991 inb $0x60, %al # read it
992 jmp empty_8042_loop
993
994 no_output:
995 testb $2, %al # is input buffer full?
996 jnz empty_8042_loop # yes - loop
997 empty_8042_end_loop:
998 popl %ecx
999 ret
1000
1001 # Read the cmos clock. Return the seconds in al
1002 gettime:
1003 pushw %cx
1004 movb $0x02, %ah
1005 int $0x1a
1006 movb %dh, %al # %dh contains the seconds
1007 andb $0x0f, %al
1008 movb %dh, %ah
1009 movb $0x04, %cl
1010 shrb %cl, %ah
1011 aad
1012 popw %cx
1013 ret
1014
1015 # Delay is needed after doing I/O
1016 delay:
1017 outb %al,$0x80
1018 ret
1019
1020 # Descriptor tables
1021 #
1022 # NOTE: The intel manual says gdt should be sixteen bytes aligned for
1023 # efficiency reasons. However, there are machines which are known not
1024 # to boot with misaligned GDTs, so alter this at your peril! If you alter
1025 # GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
1026 # empty GDT entries (one for NULL and one reserved).
1027 #
1028 # NOTE: On some CPUs, the GDT must be 8 byte aligned. This is
1029 # true for the Voyager Quad CPU card which will not boot without
1030 # This directive. 16 byte aligment is recommended by intel.
1031 #
1032 .align 16
1033 gdt:
1034 .fill GDT_ENTRY_BOOT_CS,8,0
1035
1036 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1037 .word 0 # base address = 0
1038 .word 0x9A00 # code read/exec
1039 .word 0x00CF # granularity = 4096, 386
1040 # (+5th nibble of limit)
1041
1042 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1043 .word 0 # base address = 0
1044 .word 0x9200 # data read/write
1045 .word 0x00CF # granularity = 4096, 386
1046 # (+5th nibble of limit)
1047 gdt_end:
1048 .align 4
1049
1050 .word 0 # alignment byte
1051 idt_48:
1052 .word 0 # idt limit = 0
1053 .word 0, 0 # idt base = 0L
1054
1055 .word 0 # alignment byte
1056 gdt_48:
1057 .word gdt_end - gdt - 1 # gdt limit
1058 .word 0, 0 # gdt base (filled in later)
1059
1060 #ifndef CONFIG_VGA_NOPROBE
1061 # Include video setup & detection code
1062
1063 #include "video.S"
1064 #endif
1065
1066 # Setup signature -- must be last
1067 setup_sig1: .word SIG1
1068 setup_sig2: .word SIG2
1069
1070 # After this point, there is some free space which is used by the video mode
1071 # handling code to store the temporary mode table (not used by the kernel).
1072
1073 modelist:
1074
1075 .text
1076 endtext:
1077 .data
1078 enddata:
1079 .bss
1080 endbss:
Personal OpenWRT clone
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