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 61INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way 62SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536). 63SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment 64 # ... and the former contents of CS 65 66DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020 67 68.code16 69.globl begtext, begdata, begbss, endtext, enddata, endbss 70 71.text 72begtext: 73.data 74begdata: 75.bss 76begbss: 77.text 78 79start: 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) 87realmode_swtch: .word 0, 0 # default_switch, SETUPSEG 88start_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 94type_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 100loadflags: 101LOADED_HIGH = 1 # If set, the kernel is loaded high 102CAN_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 113setup_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 120code32_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 128ramdisk_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 133ramdisk_size: .long 0 # its size in bytes 134 135bootsect_kludge: 136 .long 0 # obsolete 137 138heap_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 143pad1: .word 0 144cmd_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 159ramdisk_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 164kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment 165 #required for protected mode 166 #kernel 167#ifdef CONFIG_RELOCATABLE 168relocatable_kernel: .byte 1 169#else 170relocatable_kernel: .byte 0 171#endif 172pad2: .byte 0 173pad3: .word 0 174 175cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line, 176 #added with boot protocol 177 #version 2.06 178 179trampoline: 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 185start_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 211prtstr: 212 lodsb 213 andb %al, %al 214 jz fin 215 216 call prtchr 217 jmp prtstr 218 219fin: ret 220 221# Space printing 222prtsp2: call prtspc # Print double space 223prtspc: movb $0x20, %al # Print single space (note: fall-thru) 224 225# Part of above routine, this one just prints ascii al 226prtchr: 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 236beep: movb $0x07, %al 237 jmp prtchr 238 239no_sig_mess: .string "No setup signature found ..." 240 241good_sig1: 242 jmp good_sig 243 244# We now have to find the rest of the setup code/data 245bad_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 276no_sig: 277 lea no_sig_mess, %si 278 call prtstr 279 280no_sig_loop: 281 hlt 282 jmp no_sig_loop 283 284good_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 303loader_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. 309loader_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 3171: jmp 1b 318 319cpu_panic_mess: 320 .asciz "PANIC: CPU too old for this kernel." 321 322#include "../kernel/verify_cpu.S" 323 324cpu_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 345meme820: 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 351jmpe820: 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 # 369good820: 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 378again820: 379 cmpl $0, %ebx # check to see if 380 jne jmpe820 # %ebx is set to EOF 381bail820: 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 392meme801: 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 410e801usecxdx: 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. 420mem88: 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# 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 436 437# 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 465 466 cmpb $3, %ah 467 je is_disk1 468 469no_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 479is_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 490 491 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 503 504 movw $0x10, %cx # we keep only first 16 bytes 505sysdesc_ok: 506 rep 507 movsb 508 popw %ds 509no_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 519voyager_rep: 520 movb %es:(%di), %al 521 movb %al,(%si) 522 incw %di 523 incw %si 524 decw %cx 525 jnz voyager_rep 526no_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 536 537 movb $0xAA, (0x1ff) # device present 538no_psmouse: 539 540#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 544 545 movl %eax, (96) 546 movl %ebx, (100) 547 movl %ecx, (104) 548 movl %edx, (108) 549#endif 550 551#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 559 560 cmpw $0x0504d, %bx # Check for "PM" signature 561 jne done_apm_bios # No signature, no APM BIOS 562 563 andw $0x02, %cx # Is 32 bit supported? 564 je done_apm_bios # No 32-bit, no (good) APM BIOS 565 566 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. 577 578 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 591 592 cmpw $0x0504d, %bx # check for "PM" signature 593 jne apm_disconnect # no sig -> shouldn't happen 594 595 movw %ax, (64) # record the APM BIOS version 596 movw %cx, (76) # and flags 597 jmp done_apm_bios 598 599apm_disconnect: # Tidy up 600 movw $0x05304, %ax # Disconnect 601 xorw %bx, %bx 602 int $0x15 # ignore return code 603 604 jmp done_apm_bios 605 606no_32_apm_bios: 607 andw $0xfffd, (76) # remove 32 bit support bit 608done_apm_bios: 609#endif 610 611#include "edd.S" 612 613# Now we want to move to protected mode ... 614 cmpw $0, %cs:realmode_swtch 615 jz rmodeswtch_normal 616 617 lcall *%cs:realmode_swtch 618 619 jmp rmodeswtch_end 620 621rmodeswtch_normal: 622 pushw %cs 623 call default_switch 624 625rmodeswtch_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 634 635do_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 641do_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 658 659end_move: 660# then we load the segment descriptors 661 movw %cs, %ax # aka SETUPSEG 662 movw %ax, %ds 663 664# 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 669 670# 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 678 679 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_1 687 688 addw $INITSEG, %dx 689 subw %ax, %dx # this will go into %ss after 690 # the move 691move_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 706 707move_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 714end_move_self: # now we are at the right place 715 716# 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# 721 722#if defined(CONFIG_X86_ELAN) 723 movb $0x02, %al # alternate A20 gate 724 outb %al, $0x92 # this works on SC410/SC520 725a20_elan_wait: 726 call a20_test 727 jz a20_elan_wait 728 jmp a20_done 729#endif 730 731 732A20_TEST_LOOPS = 32 # Iterations per wait 733A20_ENABLE_LOOPS = 255 # Total loops to try 734 735 736#ifndef CONFIG_X86_VOYAGER 737a20_try_loop: 738 739 # First, see if we are on a system with no A20 gate. 740a20_none: 741 call a20_test 742 jnz a20_done 743 744 # Next, try the BIOS (INT 0x15, AX=0x2401) 745a20_bios: 746 movw $0x2401, %ax 747 pushfl # Be paranoid about flags 748 int $0x15 749 popfl 750 751 call a20_test 752 jnz a20_done 753 754 # Try enabling A20 through the keyboard controller 755#endif /* CONFIG_X86_VOYAGER */ 756a20_kbc: 757 call empty_8042 758 759#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 763 764 movb $0xD1, %al # command write 765 outb %al, $0x64 766 call empty_8042 767 768 movb $0xDF, %al # A20 on 769 outb %al, $0x60 770 call empty_8042 771 772#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. 776a20_kbc_wait: 777 xorw %cx, %cx 778a20_kbc_wait_loop: 779 call a20_test 780 jnz a20_done 781 loop a20_kbc_wait_loop 782 783 # Final attempt: use "configuration port A" 784a20_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 789 790 # Wait for configuration port A to take effect 791a20_fast_wait: 792 xorw %cx, %cx 793a20_fast_wait_loop: 794 call a20_test 795 jnz a20_done 796 loop a20_fast_wait_loop 797 798 # A20 is still not responding. Try frobbing it again. 799 # 800 decb (a20_tries) 801 jnz a20_try_loop 802 803 movw $a20_err_msg, %si 804 call prtstr 805 806a20_die: 807 hlt 808 jmp a20_die 809 810a20_tries: 811 .byte A20_ENABLE_LOOPS 812 813a20_err_msg: 814 .ascii "linux: fatal error: A20 gate not responding!" 815 .byte 13, 10, 0 816 817 # If we get here, all is good 818a20_done: 819 820#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 831 832# make sure any possible coprocessor is properly reset.. 833 xorw %ax, %ax 834 outb %al, $0xf0 835 call delay 836 837 outb %al, $0xf1 838 call delay 839 840# 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 845 846 movb $0xFB, %al # mask all irq's but irq2 which 847 outb %al, $0x21 # is cascaded 848 849# 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 865 866flush_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 872 873# 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) 883 884 .byte 0x66, 0xea # prefix + jmpi-opcode 885code32: .long startup_32 # will be set to %cs+startup_32 886 .word __BOOT_CS 887.code32 888startup_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 895 896 xorl %eax, %eax 8971: 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 901 902 # Jump to the 32bit entry point 903 jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi) 904.code16 905 906# Here's a bunch of information about your current kernel.. 907kernel_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 0 915 916# This is the default real mode switch routine. 917# to be called just before protected mode transition 918default_switch: 919 cli # no interrupts allowed ! 920 movb $0x80, %al # disable NMI for bootup 921 # sequence 922 outb %al, $0x70 923 lret 924 925 926#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. 932 933A20_TEST_ADDR = 4*0x80 934 935a20_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 945a20_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 951 952 popw %fs:(A20_TEST_ADDR) 953 popw %ax 954 popw %cx 955 ret 956 957#endif /* CONFIG_X86_VOYAGER */ 958 959# 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# 972 973empty_8042: 974 pushl %ecx 975 movl $100000, %ecx 976 977empty_8042_loop: 978 decl %ecx 979 jz empty_8042_end_loop 980 981 call delay 982 983 inb $0x64, %al # 8042 status port 984 testb $1, %al # output buffer? 985 jz no_output 986 987 call delay 988 inb $0x60, %al # read it 989 jmp empty_8042_loop 990 991no_output: 992 testb $2, %al # is input buffer full? 993 jnz empty_8042_loop # yes - loop 994empty_8042_end_loop: 995 popl %ecx 996 ret 997 998# Read the cmos clock. Return the seconds in al 999gettime: 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 1011 1012# Delay is needed after doing I/O 1013delay: 1014 outb %al,$0x80 1015 ret 1016 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 1030gdt: 1031 .fill GDT_ENTRY_BOOT_CS,8,0 1032 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) 1038 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) 1044gdt_end: 1045 .align 4 1046 1047 .word 0 # alignment byte 1048idt_48: 1049 .word 0 # idt limit = 0 1050 .word 0, 0 # idt base = 0L 1051 1052 .word 0 # alignment byte 1053gdt_48: 1054 .word gdt_end - gdt - 1 # gdt limit 1055 .word 0, 0 # gdt base (filled in later) 1056 1057# Include video setup & detection code 1058 1059#include "video.S" 1060 1061# Setup signature -- must be last 1062setup_sig1: .word SIG1 1063setup_sig2: .word SIG2 1064 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). 1067 1068modelist: 1069 1070.text 1071endtext: 1072.data 1073enddata: 1074.bss 1075endbss: 1076