| blob | 6dbcc95b21209a65e7d3050fadfc69ac7a9f8344 |
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 */
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>
57 /* Signature words to ensure LILO loaded us right */
58 #define SIG1 0xAA55
59 #define SIG2 0x5A5A
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
66 DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020
68 .code16
69 .globl begtext, begdata, begbss, endtext, enddata, endbss
71 .text
72 begtext:
73 .data
74 begdata:
75 .bss
76 begbss:
77 .text
79 start:
80 jmp trampoline
82 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
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.
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
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
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.
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
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.
133 ramdisk_size: .long 0 # its size in bytes
135 bootsect_kludge:
136 .long 0 # obsolete
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.
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.
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
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
175 cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
176 #added with boot protocol
177 #version 2.06
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 #####################################################
185 start_of_setup:
186 # Bootlin depends on this being done early
187 movw $0x01500, %ax
188 movb $0x81, %dl
189 int $0x13
191 #ifdef SAFE_RESET_DISK_CONTROLLER
192 # Reset the disk controller.
193 movw $0x0000, %ax
194 movb $0x80, %dl
195 int $0x13
196 #endif
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
205 cmpw $SIG2, setup_sig2
206 jne bad_sig
208 jmp good_sig1
210 # Routine to print asciiz string at ds:si
211 prtstr:
212 lodsb
213 andb %al, %al
214 jz fin
216 call prtchr
217 jmp prtstr
219 fin: ret
221 # Space printing
222 prtsp2: call prtspc # Print double space
223 prtspc: movb $0x20, %al # Print single space (note: fall-thru)
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
236 beep: movb $0x07, %al
237 jmp prtchr
239 no_sig_mess: .string "No setup signature found ..."
241 good_sig1:
242 jmp good_sig
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
271 cmpw $SIG2, setup_sig2
272 jne no_sig
274 jmp good_sig
276 no_sig:
277 lea no_sig_mess, %si
278 call prtstr
280 no_sig_loop:
281 hlt
282 jmp no_sig_loop
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.
292 cmpb $0, %cs:type_of_loader # Do we have a loader that
293 # can deal with us?
294 jnz loader_ok # Yes, continue.
296 pushw %cs # No, we have an old loader,
297 popw %ds # die.
298 lea loader_panic_mess, %si
299 call prtstr
301 jmp no_sig_loop
303 loader_panic_mess: .string "Wrong loader, giving up..."
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
319 cpu_panic_mess:
320 .asciz "PANIC: CPU too old for this kernel."
322 #include "../kernel/verify_cpu.S"
324 cpu_ok:
325 # Get memory size (extended mem, kB)
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
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.
343 #define SMAP 0x534d4150
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.
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
360 cmpl $SMAP, %eax # check the return is `SMAP'
361 jne bail820 # fall to e801 if it fails
363 # cmpl $1, 16(%di) # is this usable memory?
364 # jne again820
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
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:
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.)
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
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...
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.
418 # Ye Olde Traditional Methode. Returns the memory size (up to 16mb or
419 # 64mb, depending on the bios) in ax.
420 mem88:
422 #endif
423 movb $0x88, %ah
424 int $0x15
425 movw %ax, (2)
427 # Set the keyboard repeat rate to the max
428 movw $0x0305, %ax
429 xorw %bx, %bx
430 int $0x16
432 # Check for video adapter and its parameters and allow the
433 # user to browse video modes.
434 call video # NOTE: we need %ds pointing
435 # to bootsector
437 # Get hd0 data...
438 xorw %ax, %ax
439 movw %ax, %ds
440 ldsw (4 * 0x41), %si
441 movw %cs, %ax # aka SETUPSEG
442 subw $DELTA_INITSEG, %ax # aka INITSEG
443 pushw %ax
444 movw %ax, %es
445 movw $0x0080, %di
446 movw $0x10, %cx
447 pushw %cx
448 cld
449 rep
450 movsb
451 # Get hd1 data...
452 xorw %ax, %ax
453 movw %ax, %ds
454 ldsw (4 * 0x46), %si
455 popw %cx
456 popw %es
457 movw $0x0090, %di
458 rep
459 movsb
460 # Check that there IS a hd1 :-)
461 movw $0x01500, %ax
462 movb $0x81, %dl
463 int $0x13
464 jc no_disk1
466 cmpb $3, %ah
467 je is_disk1
469 no_disk1:
470 movw %cs, %ax # aka SETUPSEG
471 subw $DELTA_INITSEG, %ax # aka INITSEG
472 movw %ax, %es
473 movw $0x0090, %di
474 movw $0x10, %cx
475 xorw %ax, %ax
476 cld
477 rep
478 stosb
479 is_disk1:
480 # check for Micro Channel (MCA) bus
481 movw %cs, %ax # aka SETUPSEG
482 subw $DELTA_INITSEG, %ax # aka INITSEG
483 movw %ax, %ds
484 xorw %ax, %ax
485 movw %ax, (0xa0) # set table length to 0
486 movb $0xc0, %ah
487 stc
488 int $0x15 # moves feature table to es:bx
489 jc no_mca
491 pushw %ds
492 movw %es, %ax
493 movw %ax, %ds
494 movw %cs, %ax # aka SETUPSEG
495 subw $DELTA_INITSEG, %ax # aka INITSEG
496 movw %ax, %es
497 movw %bx, %si
498 movw $0xa0, %di
499 movw (%si), %cx
500 addw $2, %cx # table length is a short
501 cmpw $0x10, %cx
502 jc sysdesc_ok
504 movw $0x10, %cx # we keep only first 16 bytes
505 sysdesc_ok:
506 rep
507 movsb
508 popw %ds
509 no_mca:
510 #ifdef CONFIG_X86_VOYAGER
511 movb $0xff, 0x40 # flag on config found
512 movb $0xc0, %al
513 mov $0xff, %ah
514 int $0x15 # put voyager config info at es:di
515 jc no_voyager
516 movw $0x40, %si # place voyager info in apm table
517 cld
518 movw $7, %cx
519 voyager_rep:
520 movb %es:(%di), %al
521 movb %al,(%si)
522 incw %di
523 incw %si
524 decw %cx
525 jnz voyager_rep
526 no_voyager:
527 #endif
528 # Check for PS/2 pointing device
529 movw %cs, %ax # aka SETUPSEG
530 subw $DELTA_INITSEG, %ax # aka INITSEG
531 movw %ax, %ds
532 movb $0, (0x1ff) # default is no pointing device
533 int $0x11 # int 0x11: equipment list
534 testb $0x04, %al # check if mouse installed
535 jz no_psmouse
537 movb $0xAA, (0x1ff) # device present
538 no_psmouse:
540 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
541 movl $0x0000E980, %eax # IST Support
542 movl $0x47534943, %edx # Request value
543 int $0x15
545 movl %eax, (96)
546 movl %ebx, (100)
547 movl %ecx, (104)
548 movl %edx, (108)
549 #endif
551 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
552 # Then check for an APM BIOS...
553 # %ds points to the bootsector
554 movw $0, 0x40 # version = 0 means no APM BIOS
555 movw $0x05300, %ax # APM BIOS installation check
556 xorw %bx, %bx
557 int $0x15
558 jc done_apm_bios # Nope, no APM BIOS
560 cmpw $0x0504d, %bx # Check for "PM" signature
561 jne done_apm_bios # No signature, no APM BIOS
563 andw $0x02, %cx # Is 32 bit supported?
564 je done_apm_bios # No 32-bit, no (good) APM BIOS
566 movw $0x05304, %ax # Disconnect first just in case
567 xorw %bx, %bx
568 int $0x15 # ignore return code
569 movw $0x05303, %ax # 32 bit connect
570 xorl %ebx, %ebx
571 xorw %cx, %cx # paranoia :-)
572 xorw %dx, %dx # ...
573 xorl %esi, %esi # ...
574 xorw %di, %di # ...
575 int $0x15
576 jc no_32_apm_bios # Ack, error.
578 movw %ax, (66) # BIOS code segment
579 movl %ebx, (68) # BIOS entry point offset
580 movw %cx, (72) # BIOS 16 bit code segment
581 movw %dx, (74) # BIOS data segment
582 movl %esi, (78) # BIOS code segment lengths
583 movw %di, (82) # BIOS data segment length
584 # Redo the installation check as the 32 bit connect
585 # modifies the flags returned on some BIOSs
586 movw $0x05300, %ax # APM BIOS installation check
587 xorw %bx, %bx
588 xorw %cx, %cx # paranoia
589 int $0x15
590 jc apm_disconnect # error -> shouldn't happen
592 cmpw $0x0504d, %bx # check for "PM" signature
593 jne apm_disconnect # no sig -> shouldn't happen
595 movw %ax, (64) # record the APM BIOS version
596 movw %cx, (76) # and flags
597 jmp done_apm_bios
599 apm_disconnect: # Tidy up
600 movw $0x05304, %ax # Disconnect
601 xorw %bx, %bx
602 int $0x15 # ignore return code
604 jmp done_apm_bios
606 no_32_apm_bios:
607 andw $0xfffd, (76) # remove 32 bit support bit
608 done_apm_bios:
609 #endif
611 #include "edd.S"
613 # Now we want to move to protected mode ...
614 cmpw $0, %cs:realmode_swtch
615 jz rmodeswtch_normal
617 lcall *%cs:realmode_swtch
619 jmp rmodeswtch_end
621 rmodeswtch_normal:
622 pushw %cs
623 call default_switch
625 rmodeswtch_end:
626 # Now we move the system to its rightful place ... but we check if we have a
627 # big-kernel. In that case we *must* not move it ...
628 testb $LOADED_HIGH, %cs:loadflags
629 jz do_move0 # .. then we have a normal low
630 # loaded zImage
631 # .. or else we have a high
632 # loaded bzImage
633 jmp end_move # ... and we skip moving
635 do_move0:
636 movw $0x100, %ax # start of destination segment
637 movw %cs, %bp # aka SETUPSEG
638 subw $DELTA_INITSEG, %bp # aka INITSEG
639 movw %cs:start_sys_seg, %bx # start of source segment
640 cld
641 do_move:
642 movw %ax, %es # destination segment
643 incb %ah # instead of add ax,#0x100
644 movw %bx, %ds # source segment
645 addw $0x100, %bx
646 subw %di, %di
647 subw %si, %si
648 movw $0x800, %cx
649 rep
650 movsw
651 cmpw %bp, %bx # assume start_sys_seg > 0x200,
652 # so we will perhaps read one
653 # page more than needed, but
654 # never overwrite INITSEG
655 # because destination is a
656 # minimum one page below source
657 jb do_move
659 end_move:
660 # then we load the segment descriptors
661 movw %cs, %ax # aka SETUPSEG
662 movw %ax, %ds
664 # Check whether we need to be downward compatible with version <=201
665 cmpl $0, cmd_line_ptr
666 jne end_move_self # loader uses version >=202 features
667 cmpb $0x20, type_of_loader
668 je end_move_self # bootsect loader, we know of it
670 # Boot loader doesnt support boot protocol version 2.02.
671 # If we have our code not at 0x90000, we need to move it there now.
672 # We also then need to move the params behind it (commandline)
673 # Because we would overwrite the code on the current IP, we move
674 # it in two steps, jumping high after the first one.
675 movw %cs, %ax
676 cmpw $SETUPSEG, %ax
677 je end_move_self
679 cli # make sure we really have
680 # interrupts disabled !
681 # because after this the stack
682 # should not be used
683 subw $DELTA_INITSEG, %ax # aka INITSEG
684 movw %ss, %dx
685 cmpw %ax, %dx
686 jb move_self_1
688 addw $INITSEG, %dx
689 subw %ax, %dx # this will go into %ss after
690 # the move
691 move_self_1:
692 movw %ax, %ds
693 movw $INITSEG, %ax # real INITSEG
694 movw %ax, %es
695 movw %cs:setup_move_size, %cx
696 std # we have to move up, so we use
697 # direction down because the
698 # areas may overlap
699 movw %cx, %di
700 decw %di
701 movw %di, %si
702 subw $move_self_here+0x200, %cx
703 rep
704 movsb
705 ljmp $SETUPSEG, $move_self_here
707 move_self_here:
708 movw $move_self_here+0x200, %cx
709 rep
710 movsb
711 movw $SETUPSEG, %ax
712 movw %ax, %ds
713 movw %dx, %ss
714 end_move_self: # now we are at the right place
716 #
717 # Enable A20. This is at the very best an annoying procedure.
718 # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
719 # AMD Elan bug fix by Robert Schwebel.
720 #
722 #if defined(CONFIG_X86_ELAN)
723 movb $0x02, %al # alternate A20 gate
724 outb %al, $0x92 # this works on SC410/SC520
725 a20_elan_wait:
726 call a20_test
727 jz a20_elan_wait
728 jmp a20_done
729 #endif
732 A20_TEST_LOOPS = 32 # Iterations per wait
733 A20_ENABLE_LOOPS = 255 # Total loops to try
736 #ifndef CONFIG_X86_VOYAGER
737 a20_try_loop:
739 # First, see if we are on a system with no A20 gate.
740 a20_none:
741 call a20_test
742 jnz a20_done
744 # Next, try the BIOS (INT 0x15, AX=0x2401)
745 a20_bios:
746 movw $0x2401, %ax
747 pushfl # Be paranoid about flags
748 int $0x15
749 popfl
751 call a20_test
752 jnz a20_done
754 # Try enabling A20 through the keyboard controller
755 #endif /* CONFIG_X86_VOYAGER */
756 a20_kbc:
757 call empty_8042
759 #ifndef CONFIG_X86_VOYAGER
760 call a20_test # Just in case the BIOS worked
761 jnz a20_done # but had a delayed reaction.
762 #endif
764 movb $0xD1, %al # command write
765 outb %al, $0x64
766 call empty_8042
768 movb $0xDF, %al # A20 on
769 outb %al, $0x60
770 call empty_8042
772 #ifndef CONFIG_X86_VOYAGER
773 # Wait until a20 really *is* enabled; it can take a fair amount of
774 # time on certain systems; Toshiba Tecras are known to have this
775 # problem.
776 a20_kbc_wait:
777 xorw %cx, %cx
778 a20_kbc_wait_loop:
779 call a20_test
780 jnz a20_done
781 loop a20_kbc_wait_loop
783 # Final attempt: use "configuration port A"
784 a20_fast:
785 inb $0x92, %al # Configuration Port A
786 orb $0x02, %al # "fast A20" version
787 andb $0xFE, %al # don't accidentally reset
788 outb %al, $0x92
790 # Wait for configuration port A to take effect
791 a20_fast_wait:
792 xorw %cx, %cx
793 a20_fast_wait_loop:
794 call a20_test
795 jnz a20_done
796 loop a20_fast_wait_loop
798 # A20 is still not responding. Try frobbing it again.
799 #
800 decb (a20_tries)
801 jnz a20_try_loop
803 movw $a20_err_msg, %si
804 call prtstr
806 a20_die:
807 hlt
808 jmp a20_die
810 a20_tries:
811 .byte A20_ENABLE_LOOPS
813 a20_err_msg:
814 .ascii "linux: fatal error: A20 gate not responding!"
815 .byte 13, 10, 0
817 # If we get here, all is good
818 a20_done:
820 #endif /* CONFIG_X86_VOYAGER */
821 # set up gdt and idt and 32bit start address
822 lidt idt_48 # load idt with 0,0
823 xorl %eax, %eax # Compute gdt_base
824 movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
825 shll $4, %eax
826 addl %eax, code32
827 addl $gdt, %eax
828 movl %eax, (gdt_48+2)
829 lgdt gdt_48 # load gdt with whatever is
830 # appropriate
832 # make sure any possible coprocessor is properly reset..
833 xorw %ax, %ax
834 outb %al, $0xf0
835 call delay
837 outb %al, $0xf1
838 call delay
840 # well, that went ok, I hope. Now we mask all interrupts - the rest
841 # is done in init_IRQ().
842 movb $0xFF, %al # mask all interrupts for now
843 outb %al, $0xA1
844 call delay
846 movb $0xFB, %al # mask all irq's but irq2 which
847 outb %al, $0x21 # is cascaded
849 # Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
850 # need no steenking BIOS anyway (except for the initial loading :-).
851 # The BIOS-routine wants lots of unnecessary data, and it's less
852 # "interesting" anyway. This is how REAL programmers do it.
853 #
854 # Well, now's the time to actually move into protected mode. To make
855 # things as simple as possible, we do no register set-up or anything,
856 # we let the gnu-compiled 32-bit programs do that. We just jump to
857 # absolute address 0x1000 (or the loader supplied one),
858 # in 32-bit protected mode.
859 #
860 # Note that the short jump isn't strictly needed, although there are
861 # reasons why it might be a good idea. It won't hurt in any case.
862 movw $1, %ax # protected mode (PE) bit
863 lmsw %ax # This is it!
864 jmp flush_instr
866 flush_instr:
867 xorw %bx, %bx # Flag to indicate a boot
868 xorl %esi, %esi # Pointer to real-mode code
869 movw %cs, %si
870 subw $DELTA_INITSEG, %si
871 shll $4, %esi # Convert to 32-bit pointer
873 # jump to startup_32 in arch/i386/boot/compressed/head.S
874 #
875 # NOTE: For high loaded big kernels we need a
876 # jmpi 0x100000,__BOOT_CS
877 #
878 # but we yet haven't reloaded the CS register, so the default size
879 # of the target offset still is 16 bit.
880 # However, using an operand prefix (0x66), the CPU will properly
881 # take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
882 # Manual, Mixing 16-bit and 32-bit code, page 16-6)
884 .byte 0x66, 0xea # prefix + jmpi-opcode
885 code32: .long startup_32 # will be set to %cs+startup_32
886 .word __BOOT_CS
887 .code32
888 startup_32:
889 movl $(__BOOT_DS), %eax
890 movl %eax, %ds
891 movl %eax, %es
892 movl %eax, %fs
893 movl %eax, %gs
894 movl %eax, %ss
896 xorl %eax, %eax
897 1: incl %eax # check that A20 really IS enabled
898 movl %eax, 0x00000000 # loop forever if it isn't
899 cmpl %eax, 0x00100000
900 je 1b
902 # Jump to the 32bit entry point
903 jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi)
904 .code16
906 # Here's a bunch of information about your current kernel..
907 kernel_version: .ascii UTS_RELEASE
908 .ascii " ("
909 .ascii LINUX_COMPILE_BY
910 .ascii "@"
911 .ascii LINUX_COMPILE_HOST
912 .ascii ") "
913 .ascii UTS_VERSION
914 .byte 0
916 # This is the default real mode switch routine.
917 # to be called just before protected mode transition
918 default_switch:
919 cli # no interrupts allowed !
920 movb $0x80, %al # disable NMI for bootup
921 # sequence
922 outb %al, $0x70
923 lret
926 #ifndef CONFIG_X86_VOYAGER
927 # This routine tests whether or not A20 is enabled. If so, it
928 # exits with zf = 0.
929 #
930 # The memory address used, 0x200, is the int $0x80 vector, which
931 # should be safe.
933 A20_TEST_ADDR = 4*0x80
935 a20_test:
936 pushw %cx
937 pushw %ax
938 xorw %cx, %cx
939 movw %cx, %fs # Low memory
940 decw %cx
941 movw %cx, %gs # High memory area
942 movw $A20_TEST_LOOPS, %cx
943 movw %fs:(A20_TEST_ADDR), %ax
944 pushw %ax
945 a20_test_wait:
946 incw %ax
947 movw %ax, %fs:(A20_TEST_ADDR)
948 call delay # Serialize and make delay constant
949 cmpw %gs:(A20_TEST_ADDR+0x10), %ax
950 loope a20_test_wait
952 popw %fs:(A20_TEST_ADDR)
953 popw %ax
954 popw %cx
955 ret
957 #endif /* CONFIG_X86_VOYAGER */
959 # This routine checks that the keyboard command queue is empty
960 # (after emptying the output buffers)
961 #
962 # Some machines have delusions that the keyboard buffer is always full
963 # with no keyboard attached...
964 #
965 # If there is no keyboard controller, we will usually get 0xff
966 # to all the reads. With each IO taking a microsecond and
967 # a timeout of 100,000 iterations, this can take about half a
968 # second ("delay" == outb to port 0x80). That should be ok,
969 # and should also be plenty of time for a real keyboard controller
970 # to empty.
971 #
973 empty_8042:
974 pushl %ecx
975 movl $100000, %ecx
977 empty_8042_loop:
978 decl %ecx
979 jz empty_8042_end_loop
981 call delay
983 inb $0x64, %al # 8042 status port
984 testb $1, %al # output buffer?
985 jz no_output
987 call delay
988 inb $0x60, %al # read it
989 jmp empty_8042_loop
991 no_output:
992 testb $2, %al # is input buffer full?
993 jnz empty_8042_loop # yes - loop
994 empty_8042_end_loop:
995 popl %ecx
996 ret
998 # Read the cmos clock. Return the seconds in al
999 gettime:
1000 pushw %cx
1001 movb $0x02, %ah
1002 int $0x1a
1003 movb %dh, %al # %dh contains the seconds
1004 andb $0x0f, %al
1005 movb %dh, %ah
1006 movb $0x04, %cl
1007 shrb %cl, %ah
1008 aad
1009 popw %cx
1010 ret
1012 # Delay is needed after doing I/O
1013 delay:
1014 outb %al,$0x80
1015 ret
1017 # Descriptor tables
1018 #
1019 # NOTE: The intel manual says gdt should be sixteen bytes aligned for
1020 # efficiency reasons. However, there are machines which are known not
1021 # to boot with misaligned GDTs, so alter this at your peril! If you alter
1022 # GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
1023 # empty GDT entries (one for NULL and one reserved).
1024 #
1025 # NOTE: On some CPUs, the GDT must be 8 byte aligned. This is
1026 # true for the Voyager Quad CPU card which will not boot without
1027 # This directive. 16 byte aligment is recommended by intel.
1028 #
1029 .align 16
1030 gdt:
1031 .fill GDT_ENTRY_BOOT_CS,8,0
1033 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1034 .word 0 # base address = 0
1035 .word 0x9A00 # code read/exec
1036 .word 0x00CF # granularity = 4096, 386
1037 # (+5th nibble of limit)
1039 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1040 .word 0 # base address = 0
1041 .word 0x9200 # data read/write
1042 .word 0x00CF # granularity = 4096, 386
1043 # (+5th nibble of limit)
1044 gdt_end:
1045 .align 4
1047 .word 0 # alignment byte
1048 idt_48:
1049 .word 0 # idt limit = 0
1050 .word 0, 0 # idt base = 0L
1052 .word 0 # alignment byte
1053 gdt_48:
1054 .word gdt_end - gdt - 1 # gdt limit
1055 .word 0, 0 # gdt base (filled in later)
1057 # Include video setup & detection code
1059 #include "video.S"
1061 # Setup signature -- must be last
1062 setup_sig1: .word SIG1
1063 setup_sig2: .word SIG2
1065 # After this point, there is some free space which is used by the video mode
1066 # handling code to store the temporary mode table (not used by the kernel).
1068 modelist:
1070 .text
1071 endtext:
1072 .data
1073 enddata:
1074 .bss
1075 endbss: