2 * setup.S Copyright (C) 1991, 1992 Linus Torvalds
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.
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
14 * Move PS/2 aux init code to psaux.c
15 * (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
17 * some changes and additional features by Christoph Niemann,
18 * March 1993/June 1994 (Christoph.Niemann@linux.org)
20 * add APM BIOS checking by Stephen Rothwell, May 1994
21 * (sfr@canb.auug.org.au)
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>
27 * Video handling moved to video.S by Martin Mares, March 1996
28 * <mj@k332.feld.cvut.cz>
30 * Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
31 * parsons) to avoid loadlin confusion, July 1997
33 * Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
34 * <stiker@northlink.com>
36 * Fix to work around buggy BIOSes which dont 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>
45 * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
46 * by Robert Schwebel, December 2001 <robert@schwebel.de>
48 * BIOS Enhanced Disk Drive support
49 * by Matt Domsch <Matt_Domsch@dell.com> October 2002
50 * conformant to T13 Committee www.t13.org
51 * projects 1572D, 1484D, 1386D, 1226DT
52 * disk signature read by Matt Domsch <Matt_Domsch@dell.com>
53 * and Andrew Wilks <Andrew_Wilks@dell.com> September 2003
56 #include <linux/config.h>
57 #include <asm/segment.h>
58 #include <linux/version.h>
59 #include <linux/compile.h>
65 /* Signature words to ensure LILO loaded us right */
69 INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way
70 SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536).
71 SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment
72 # ... and the former contents of CS
74 DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020
77 .globl begtext, begdata, begbss, endtext, enddata, endbss
90 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
92 .ascii "HdrS" # header signature
93 .word 0x0203 # header version number (>= 0x0105)
94 # or else old loadlin-1.5 will fail)
95 realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
96 start_sys_seg: .word SYSSEG
97 .word kernel_version # pointing to kernel version string
98 # above section of header is compatible
99 # with loadlin-1.5 (header v1.5). Don't
102 type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
103 # Bootlin, SYSLX, bootsect...)
104 # See Documentation/i386/boot.txt for
107 # flags, unused bits must be zero (RFU) bit within loadflags
109 LOADED_HIGH = 1 # If set, the kernel is loaded high
110 CAN_USE_HEAP = 0x80 # If set, the loader also has set
111 # heap_end_ptr to tell how much
112 # space behind setup.S can be used for
114 # Only the loader knows what is free
115 #ifndef __BIG_KERNEL__
121 setup_move_size: .word 0x8000 # size to move, when setup is not
122 # loaded at 0x90000. We will move setup
123 # to 0x90000 then just before jumping
124 # into the kernel. However, only the
125 # loader knows how much data behind
126 # us also needs to be loaded.
128 code32_start: # here loaders can put a different
129 # start address for 32-bit code.
130 #ifndef __BIG_KERNEL__
131 .long 0x1000 # 0x1000 = default for zImage
133 .long 0x100000 # 0x100000 = default for big kernel
136 ramdisk_image: .long 0 # address of loaded ramdisk image
137 # Here the loader puts the 32-bit
138 # address where it loaded the image.
139 # This only will be read by the kernel.
141 ramdisk_size: .long 0 # its size in bytes
144 .word bootsect_helper, SETUPSEG
146 heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later)
147 # space from here (exclusive) down to
148 # end of setup code can be used by setup
149 # for local heap purposes.
152 cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
153 # If nonzero, a 32-bit pointer
154 # to the kernel command line.
155 # The command line should be
156 # located between the start of
157 # setup and the end of low
158 # memory (0xa0000), or it may
159 # get overwritten before it
160 # gets read. If this field is
161 # used, there is no longer
162 # anything magical about the
163 # 0x90000 segment; the setup
164 # can be located anywhere in
165 # low memory 0x10000 or higher.
167 ramdisk_max: .long MAXMEM-1 # (Header version 0x0203 or later)
168 # The highest safe address for
169 # the contents of an initrd
171 trampoline: call start_of_setup
173 # End of setup header #####################################################
176 # Bootlin depends on this being done early
181 #ifdef SAFE_RESET_DISK_CONTROLLER
182 # Reset the disk controller.
188 # Set %ds = %cs, we know that SETUPSEG = %cs at this point
189 movw %cs, %ax # aka SETUPSEG
191 # Check signature at end of setup
192 cmpw $SIG1, setup_sig1
195 cmpw $SIG2, setup_sig2
200 # Routine to print asciiz string at ds:si
212 prtsp2: call prtspc # Print double space
213 prtspc: movb $0x20, %al # Print single space (note: fall-thru)
215 # Part of above routine, this one just prints ascii al
226 beep: movb $0x07, %al
229 no_sig_mess: .string "No setup signature found ..."
234 # We now have to find the rest of the setup code/data
236 movw %cs, %ax # SETUPSEG
237 subw $DELTA_INITSEG, %ax # INITSEG
240 movb (497), %bl # get setup sect from bootsect
241 subw $4, %bx # LILO loads 4 sectors of setup
242 shlw $8, %bx # convert to words (1sect=2^8 words)
244 shrw $3, %bx # convert to segment
246 movw %bx, %cs:start_sys_seg
247 # Move rest of setup code/data to here
248 movw $2048, %di # four sectors loaded by LILO
256 movw %cs, %ax # aka SETUPSEG
258 cmpw $SIG1, setup_sig1
261 cmpw $SIG2, setup_sig2
275 movw %cs, %ax # aka SETUPSEG
276 subw $DELTA_INITSEG, %ax # aka INITSEG
278 # Check if an old loader tries to load a big-kernel
279 testb $LOADED_HIGH, %cs:loadflags # Do we have a big kernel?
280 jz loader_ok # No, no danger for old loaders.
282 cmpb $0, %cs:type_of_loader # Do we have a loader that
284 jnz loader_ok # Yes, continue.
286 pushw %cs # No, we have an old loader,
288 lea loader_panic_mess, %si
293 loader_panic_mess: .string "Wrong loader, giving up..."
296 # Get memory size (extended mem, kB)
300 #ifndef STANDARD_MEMORY_BIOS_CALL
302 # Try three different memory detection schemes. First, try
303 # e820h, which lets us assemble a memory map, then try e801h,
304 # which returns a 32-bit memory size, and finally 88h, which
308 # the memory map from hell. e820h returns memory classified into
309 # a whole bunch of different types, and allows memory holes and
310 # everything. We scan through this memory map and build a list
311 # of the first 32 memory areas, which we return at [E820MAP].
312 # This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.
314 #define SMAP 0x534d4150
317 xorl %ebx, %ebx # continuation counter
318 movw $E820MAP, %di # point into the whitelist
319 # so we can have the bios
320 # directly write into it.
323 movl $0x0000e820, %eax # e820, upper word zeroed
324 movl $SMAP, %edx # ascii 'SMAP'
325 movl $20, %ecx # size of the e820rec
326 pushw %ds # data record.
328 int $0x15 # make the call
329 jc bail820 # fall to e801 if it fails
331 cmpl $SMAP, %eax # check the return is `SMAP'
332 jne bail820 # fall to e801 if it fails
334 # cmpl $1, 16(%di) # is this usable memory?
337 # If this is usable memory, we save it by simply advancing %di by
341 movb (E820NR), %al # up to 32 entries
350 cmpl $0, %ebx # check to see if
351 jne jmpe820 # %ebx is set to EOF
356 # memory size is in 1k chunksizes, to avoid confusing loadlin.
357 # we store the 0xe801 memory size in a completely different place,
358 # because it will most likely be longer than 16 bits.
359 # (use 1e0 because that's what Larry Augustine uses in his
360 # alternative new memory detection scheme, and it's sensible
361 # to write everything into the same place.)
364 stc # fix to work around buggy
365 xorw %cx,%cx # BIOSes which dont clear/set
366 xorw %dx,%dx # carry on pass/error of
367 # e801h memory size call
368 # or merely pass cx,dx though
369 # without changing them.
374 cmpw $0x0, %cx # Kludge to handle BIOSes
375 jne e801usecxdx # which report their extended
376 cmpw $0x0, %dx # memory in AX/BX rather than
377 jne e801usecxdx # CX/DX. The spec I have read
378 movw %ax, %cx # seems to indicate AX/BX
379 movw %bx, %dx # are more reasonable anyway...
382 andl $0xffff, %edx # clear sign extend
383 shll $6, %edx # and go from 64k to 1k chunks
384 movl %edx, (0x1e0) # store extended memory size
385 andl $0xffff, %ecx # clear sign extend
386 addl %ecx, (0x1e0) # and add lower memory into
389 # Ye Olde Traditional Methode. Returns the memory size (up to 16mb or
390 # 64mb, depending on the bios) in ax.
398 # Set the keyboard repeat rate to the max
403 # Check for video adapter and its parameters and allow the
404 # user to browse video modes.
405 call video # NOTE: we need %ds pointing
412 movw %cs, %ax # aka SETUPSEG
413 subw $DELTA_INITSEG, %ax # aka INITSEG
431 # Check that there IS a hd1 :-)
441 movw %cs, %ax # aka SETUPSEG
442 subw $DELTA_INITSEG, %ax # aka INITSEG
451 # check for Micro Channel (MCA) bus
452 movw %cs, %ax # aka SETUPSEG
453 subw $DELTA_INITSEG, %ax # aka INITSEG
456 movw %ax, (0xa0) # set table length to 0
459 int $0x15 # moves feature table to es:bx
465 movw %cs, %ax # aka SETUPSEG
466 subw $DELTA_INITSEG, %ax # aka INITSEG
471 addw $2, %cx # table length is a short
475 movw $0x10, %cx # we keep only first 16 bytes
481 #ifdef CONFIG_X86_VOYAGER
482 movb $0xff, 0x40 # flag on config found
485 int $0x15 # put voyager config info at es:di
487 movw $0x40, %si # place voyager info in apm table
499 # Check for PS/2 pointing device
500 movw %cs, %ax # aka SETUPSEG
501 subw $DELTA_INITSEG, %ax # aka INITSEG
503 movw $0, (0x1ff) # default is no pointing device
504 int $0x11 # int 0x11: equipment list
505 testb $0x04, %al # check if mouse installed
508 movw $0xAA, (0x1ff) # device present
511 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
512 movl $0x0000E980, %eax # IST Support
513 movl $0x47534943, %edx # Request value
522 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
523 # Then check for an APM BIOS...
524 # %ds points to the bootsector
525 movw $0, 0x40 # version = 0 means no APM BIOS
526 movw $0x05300, %ax # APM BIOS installation check
529 jc done_apm_bios # Nope, no APM BIOS
531 cmpw $0x0504d, %bx # Check for "PM" signature
532 jne done_apm_bios # No signature, no APM BIOS
534 andw $0x02, %cx # Is 32 bit supported?
535 je done_apm_bios # No 32-bit, no (good) APM BIOS
537 movw $0x05304, %ax # Disconnect first just in case
539 int $0x15 # ignore return code
540 movw $0x05303, %ax # 32 bit connect
542 xorw %cx, %cx # paranoia :-)
544 xorl %esi, %esi # ...
547 jc no_32_apm_bios # Ack, error.
549 movw %ax, (66) # BIOS code segment
550 movl %ebx, (68) # BIOS entry point offset
551 movw %cx, (72) # BIOS 16 bit code segment
552 movw %dx, (74) # BIOS data segment
553 movl %esi, (78) # BIOS code segment lengths
554 movw %di, (82) # BIOS data segment length
555 # Redo the installation check as the 32 bit connect
556 # modifies the flags returned on some BIOSs
557 movw $0x05300, %ax # APM BIOS installation check
559 xorw %cx, %cx # paranoia
561 jc apm_disconnect # error -> shouldn't happen
563 cmpw $0x0504d, %bx # check for "PM" signature
564 jne apm_disconnect # no sig -> shouldn't happen
566 movw %ax, (64) # record the APM BIOS version
567 movw %cx, (76) # and flags
570 apm_disconnect: # Tidy up
571 movw $0x05304, %ax # Disconnect
573 int $0x15 # ignore return code
578 andw $0xfffd, (76) # remove 32 bit support bit
582 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
583 # Read the first sector of device 80h and store the 4-byte signature
584 movl $0xFFFFFFFF, %eax
585 movl %eax, (DISK80_SIG_BUFFER) # assume failure
586 movb $READ_SECTORS, %ah
587 movb $1, %al # read 1 sector
588 movb $0x80, %dl # from device 80
589 movb $0, %dh # at head 0
590 movw $1, %cx # cylinder 0, sector 0
597 movl (EDDBUF+MBR_SIG_OFFSET), %eax
598 movl %eax, (DISK80_SIG_BUFFER) # store success
602 # Do the BIOS Enhanced Disk Drive calls
603 # This consists of two calls:
604 # int 13h ah=41h "Check Extensions Present"
605 # int 13h ah=48h "Get Device Parameters"
607 # A buffer of size EDDMAXNR*(EDDEXTSIZE+EDDPARMSIZE) is reserved for our use
608 # in the empty_zero_page at EDDBUF. The first four bytes of which are
609 # used to store the device number, interface support map and version
610 # results from fn41. The following 74 bytes are used to store
611 # the results from fn48. Starting from device 80h, fn41, then fn48
612 # are called and their results stored in EDDBUF+n*(EDDEXTSIZE+EDDPARMIZE).
613 # Then the pointer is incremented to store the data for the next call.
614 # This repeats until either a device doesn't exist, or until EDDMAXNR
615 # devices have been stored.
616 # The one tricky part is that ds:si always points four bytes into
617 # the structure, and the fn41 results are stored at offsets
618 # from there. This removes the need to increment the pointer for
619 # every store, and leaves it ready for the fn48 call.
620 # A second one-byte buffer, EDDNR, in the empty_zero_page stores
621 # the number of BIOS devices which exist, up to EDDMAXNR.
622 # In setup.c, copy_edd() stores both empty_zero_page buffers away
623 # for later use, as they would get overwritten otherwise.
624 # This code is sensitive to the size of the structs in edd.h
626 # %ds points to the bootsector
627 # result buffer for fn48
628 movw $EDDBUF+EDDEXTSIZE, %si # in ds:si, fn41 results
629 # kept just before that
630 movb $0, (EDDNR) # zero value at EDDNR
631 movb $0x80, %dl # BIOS device 0x80
634 movb $CHECKEXTENSIONSPRESENT, %ah # Function 41
635 movw $EDDMAGIC1, %bx # magic
636 int $0x13 # make the call
637 jc edd_done # no more BIOS devices
639 cmpw $EDDMAGIC2, %bx # is magic right?
640 jne edd_next # nope, next...
642 movb %dl, %ds:-4(%si) # store device number
643 movb %ah, %ds:-3(%si) # store version
644 movw %cx, %ds:-2(%si) # store extensions
645 incb (EDDNR) # note that we stored something
647 edd_get_device_params:
648 movw $EDDPARMSIZE, %ds:(%si) # put size
649 movb $GETDEVICEPARAMETERS, %ah # Function 48
650 int $0x13 # make the call
651 # Don't check for fail return
653 movw %si, %ax # increment si
654 addw $EDDPARMSIZE+EDDEXTSIZE, %ax
658 incb %dl # increment to next device
659 cmpb $EDDMAXNR, (EDDNR) # Out of space?
660 jb edd_check_ext # keep looping
665 # Now we want to move to protected mode ...
666 cmpw $0, %cs:realmode_swtch
669 lcall *%cs:realmode_swtch
678 # we get the code32 start address and modify the below 'jmpi'
679 # (loader may have changed it)
680 movl %cs:code32_start, %eax
681 movl %eax, %cs:code32
683 # Now we move the system to its rightful place ... but we check if we have a
684 # big-kernel. In that case we *must* not move it ...
685 testb $LOADED_HIGH, %cs:loadflags
686 jz do_move0 # .. then we have a normal low
688 # .. or else we have a high
690 jmp end_move # ... and we skip moving
693 movw $0x100, %ax # start of destination segment
694 movw %cs, %bp # aka SETUPSEG
695 subw $DELTA_INITSEG, %bp # aka INITSEG
696 movw %cs:start_sys_seg, %bx # start of source segment
699 movw %ax, %es # destination segment
700 incb %ah # instead of add ax,#0x100
701 movw %bx, %ds # source segment
708 cmpw %bp, %bx # assume start_sys_seg > 0x200,
709 # so we will perhaps read one
710 # page more than needed, but
711 # never overwrite INITSEG
712 # because destination is a
713 # minimum one page below source
717 # then we load the segment descriptors
718 movw %cs, %ax # aka SETUPSEG
721 # Check whether we need to be downward compatible with version <=201
722 cmpl $0, cmd_line_ptr
723 jne end_move_self # loader uses version >=202 features
724 cmpb $0x20, type_of_loader
725 je end_move_self # bootsect loader, we know of it
727 # Boot loader doesnt support boot protocol version 2.02.
728 # If we have our code not at 0x90000, we need to move it there now.
729 # We also then need to move the params behind it (commandline)
730 # Because we would overwrite the code on the current IP, we move
731 # it in two steps, jumping high after the first one.
736 cli # make sure we really have
737 # interrupts disabled !
738 # because after this the stack
740 subw $DELTA_INITSEG, %ax # aka INITSEG
746 subw %ax, %dx # this will go into %ss after
750 movw $INITSEG, %ax # real INITSEG
752 movw %cs:setup_move_size, %cx
753 std # we have to move up, so we use
754 # direction down because the
759 subw $move_self_here+0x200, %cx
762 ljmp $SETUPSEG, $move_self_here
765 movw $move_self_here+0x200, %cx
771 end_move_self: # now we are at the right place
774 # Enable A20. This is at the very best an annoying procedure.
775 # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
776 # AMD Elan bug fix by Robert Schwebel.
779 #if defined(CONFIG_MELAN)
780 movb $0x02, %al # alternate A20 gate
781 outb %al, $0x92 # this works on SC410/SC520
789 A20_TEST_LOOPS = 32 # Iterations per wait
790 A20_ENABLE_LOOPS = 255 # Total loops to try
793 #ifndef CONFIG_X86_VOYAGER
796 # First, see if we are on a system with no A20 gate.
801 # Next, try the BIOS (INT 0x15, AX=0x2401)
804 pushfl # Be paranoid about flags
811 # Try enabling A20 through the keyboard controller
812 #endif /* CONFIG_X86_VOYAGER */
816 #ifndef CONFIG_X86_VOYAGER
817 call a20_test # Just in case the BIOS worked
818 jnz a20_done # but had a delayed reaction.
821 movb $0xD1, %al # command write
825 movb $0xDF, %al # A20 on
829 #ifndef CONFIG_X86_VOYAGER
830 # Wait until a20 really *is* enabled; it can take a fair amount of
831 # time on certain systems; Toshiba Tecras are known to have this
838 loop a20_kbc_wait_loop
840 # Final attempt: use "configuration port A"
842 inb $0x92, %al # Configuration Port A
843 orb $0x02, %al # "fast A20" version
844 andb $0xFE, %al # don't accidentally reset
847 # Wait for configuration port A to take effect
853 loop a20_fast_wait_loop
855 # A20 is still not responding. Try frobbing it again.
860 movw $a20_err_msg, %si
868 .byte A20_ENABLE_LOOPS
871 .ascii "linux: fatal error: A20 gate not responding!"
874 # If we get here, all is good
877 #endif /* CONFIG_X86_VOYAGER */
879 lidt idt_48 # load idt with 0,0
880 xorl %eax, %eax # Compute gdt_base
881 movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
884 movl %eax, (gdt_48+2)
885 lgdt gdt_48 # load gdt with whatever is
888 # make sure any possible coprocessor is properly reset..
896 # well, that went ok, I hope. Now we mask all interrupts - the rest
897 # is done in init_IRQ().
898 movb $0xFF, %al # mask all interrupts for now
902 movb $0xFB, %al # mask all irq's but irq2 which
903 outb %al, $0x21 # is cascaded
905 # Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
906 # need no steenking BIOS anyway (except for the initial loading :-).
907 # The BIOS-routine wants lots of unnecessary data, and it's less
908 # "interesting" anyway. This is how REAL programmers do it.
910 # Well, now's the time to actually move into protected mode. To make
911 # things as simple as possible, we do no register set-up or anything,
912 # we let the gnu-compiled 32-bit programs do that. We just jump to
913 # absolute address 0x1000 (or the loader supplied one),
914 # in 32-bit protected mode.
916 # Note that the short jump isn't strictly needed, although there are
917 # reasons why it might be a good idea. It won't hurt in any case.
918 movw $1, %ax # protected mode (PE) bit
919 lmsw %ax # This is it!
923 xorw %bx, %bx # Flag to indicate a boot
924 xorl %esi, %esi # Pointer to real-mode code
926 subw $DELTA_INITSEG, %si
927 shll $4, %esi # Convert to 32-bit pointer
929 # jump to startup_32 in arch/i386/kernel/head.S
931 # NOTE: For high loaded big kernels we need a
932 # jmpi 0x100000,__BOOT_CS
934 # but we yet haven't reloaded the CS register, so the default size
935 # of the target offset still is 16 bit.
936 # However, using an operand prefix (0x66), the CPU will properly
937 # take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
938 # Manual, Mixing 16-bit and 32-bit code, page 16-6)
940 .byte 0x66, 0xea # prefix + jmpi-opcode
941 code32: .long 0x1000 # will be set to 0x100000
945 # Here's a bunch of information about your current kernel..
946 kernel_version: .ascii UTS_RELEASE
948 .ascii LINUX_COMPILE_BY
950 .ascii LINUX_COMPILE_HOST
955 # This is the default real mode switch routine.
956 # to be called just before protected mode transition
958 cli # no interrupts allowed !
959 movb $0x80, %al # disable NMI for bootup
964 # This routine only gets called, if we get loaded by the simple
965 # bootsect loader _and_ have a bzImage to load.
966 # Because there is no place left in the 512 bytes of the boot sector,
967 # we must emigrate to code space here.
969 cmpw $0, %cs:bootsect_es
972 movb $0x20, %cs:type_of_loader
975 movb %ah, %cs:bootsect_src_base+2
977 movw %ax, %cs:bootsect_es
979 lret # nothing else to do for now
985 testw %bx, %bx # 64K full?
988 movw $0x8000, %cx # full 64K, INT15 moves words
991 movw $bootsect_gdt, %si
994 jc bootsect_panic # this, if INT15 fails
996 movw %cs:bootsect_es, %es # we reset %es to always point
997 incb %cs:bootsect_dst_base+2 # to 0x10000
999 movb %cs:bootsect_dst_base+2, %ah
1000 shlb $4, %ah # we now have the number of
1001 # moved frames in %ax
1016 .byte 0x00, 0x00, 0x01 # base = 0x010000
1017 .byte 0x93 # typbyte
1018 .word 0 # limit16,base24 =0
1024 .byte 0x00, 0x00, 0x10 # base = 0x100000
1025 .byte 0x93 # typbyte
1026 .word 0 # limit16,base24 =0
1027 .word 0, 0, 0, 0 # BIOS CS
1028 .word 0, 0, 0, 0 # BIOS DS
1037 leaw bootsect_panic_mess, %si
1040 bootsect_panic_loop:
1041 jmp bootsect_panic_loop
1043 bootsect_panic_mess:
1044 .string "INT15 refuses to access high mem, giving up."
1047 #ifndef CONFIG_X86_VOYAGER
1048 # This routine tests whether or not A20 is enabled. If so, it
1049 # exits with zf = 0.
1051 # The memory address used, 0x200, is the int $0x80 vector, which
1054 A20_TEST_ADDR = 4*0x80
1060 movw %cx, %fs # Low memory
1062 movw %cx, %gs # High memory area
1063 movw $A20_TEST_LOOPS, %cx
1064 movw %fs:(A20_TEST_ADDR), %ax
1068 movw %ax, %fs:(A20_TEST_ADDR)
1069 call delay # Serialize and make delay constant
1070 cmpw %gs:(A20_TEST_ADDR+0x10), %ax
1073 popw %fs:(A20_TEST_ADDR)
1078 #endif /* CONFIG_X86_VOYAGER */
1080 # This routine checks that the keyboard command queue is empty
1081 # (after emptying the output buffers)
1083 # Some machines have delusions that the keyboard buffer is always full
1084 # with no keyboard attached...
1086 # If there is no keyboard controller, we will usually get 0xff
1087 # to all the reads. With each IO taking a microsecond and
1088 # a timeout of 100,000 iterations, this can take about half a
1089 # second ("delay" == outb to port 0x80). That should be ok,
1090 # and should also be plenty of time for a real keyboard controller
1100 jz empty_8042_end_loop
1104 inb $0x64, %al # 8042 status port
1105 testb $1, %al # output buffer?
1109 inb $0x60, %al # read it
1113 testb $2, %al # is input buffer full?
1114 jnz empty_8042_loop # yes - loop
1115 empty_8042_end_loop:
1119 # Read the cmos clock. Return the seconds in al
1124 movb %dh, %al # %dh contains the seconds
1133 # Delay is needed after doing I/O
1140 # NOTE: The intel manual says gdt should be sixteen bytes aligned for
1141 # efficiency reasons. However, there are machines which are known not
1142 # to boot with misaligned GDTs, so alter this at your peril! If you alter
1143 # GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
1144 # empty GDT entries (one for NULL and one reserved).
1146 # NOTE: On some CPUs, the GDT must be 8 byte aligned. This is
1147 # true for the Voyager Quad CPU card which will not boot without
1148 # This directive. 16 byte aligment is recommended by intel.
1152 .fill GDT_ENTRY_BOOT_CS,8,0
1154 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1155 .word 0 # base address = 0
1156 .word 0x9A00 # code read/exec
1157 .word 0x00CF # granularity = 4096, 386
1158 # (+5th nibble of limit)
1160 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
1161 .word 0 # base address = 0
1162 .word 0x9200 # data read/write
1163 .word 0x00CF # granularity = 4096, 386
1164 # (+5th nibble of limit)
1168 .word 0 # alignment byte
1170 .word 0 # idt limit = 0
1171 .word 0, 0 # idt base = 0L
1173 .word 0 # alignment byte
1175 .word gdt_end - gdt - 1 # gdt limit
1176 .word 0, 0 # gdt base (filled in later)
1178 # Include video setup & detection code
1182 # Setup signature -- must be last
1183 setup_sig1: .word SIG1
1184 setup_sig2: .word SIG2
1186 # After this point, there is some free space which is used by the video mode
1187 # handling code to store the temporary mode table (not used by the kernel).