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 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>
  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 <linux/config.h>
  50 #include <asm/segment.h>
  51 #include <linux/version.h>
  52 #include <linux/compile.h>
  53 #include <asm/boot.h>
  54 #include <asm/e820.h>
  55 #include <asm/page.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   0x0203          # 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 trampoline:     call    start_of_setup
 165                 .align 16
 166                                         # The offset at this point is 0x240
 167                 .space  (0x7ff-0x240+1) # E820 & EDD space (ending at 0x7ff)
 168 # End of setup header #####################################################
 169
 170 start_of_setup:
 171 # Bootlin depends on this being done early
 172         movw    $0x01500, %ax
 173         movb    $0x81, %dl
 174         int     $0x13
 175
 176 #ifdef SAFE_RESET_DISK_CONTROLLER
 177 # Reset the disk controller.
 178         movw    $0x0000, %ax
 179         movb    $0x80, %dl
 180         int     $0x13
 181 #endif
 182
 183 # Set %ds = %cs, we know that SETUPSEG = %cs at this point
 184         movw    %cs, %ax                # aka SETUPSEG
 185         movw    %ax, %ds
 186 # Check signature at end of setup
 187         cmpw    $SIG1, setup_sig1
 188         jne     bad_sig
 189
 190         cmpw    $SIG2, setup_sig2
 191         jne     bad_sig
 192
 193         jmp     good_sig1
 194
 195 # Routine to print asciiz string at ds:si
 196 prtstr:
 197         lodsb
 198         andb    %al, %al
 199         jz      fin
 200
 201         call    prtchr
 202         jmp     prtstr
 203
 204 fin:    ret
 205
 206 # Space printing
 207 prtsp2: call    prtspc          # Print double space
 208 prtspc: movb    $0x20, %al      # Print single space (note: fall-thru)
 209
 210 # Part of above routine, this one just prints ascii al
 211 prtchr: pushw   %ax
 212         pushw   %cx
 213         movw    $7,%bx
 214         movw    $0x01, %cx
 215         movb    $0x0e, %ah
 216         int     $0x10
 217         popw    %cx
 218         popw    %ax
 219         ret
 220
 221 beep:   movb    $0x07, %al
 222         jmp     prtchr
 223
 224 no_sig_mess: .string    "No setup signature found ..."
 225
 226 good_sig1:
 227         jmp     good_sig
 228
 229 # We now have to find the rest of the setup code/data
 230 bad_sig:
 231         movw    %cs, %ax                        # SETUPSEG
 232         subw    $DELTA_INITSEG, %ax             # INITSEG
 233         movw    %ax, %ds
 234         xorb    %bh, %bh
 235         movb    (497), %bl                      # get setup sect from bootsect
 236         subw    $4, %bx                         # LILO loads 4 sectors of setup
 237         shlw    $8, %bx                         # convert to words (1sect=2^8 words)
 238         movw    %bx, %cx
 239         shrw    $3, %bx                         # convert to segment
 240         addw    $SYSSEG, %bx
 241         movw    %bx, %cs:start_sys_seg
 242 # Move rest of setup code/data to here
 243         movw    $2048, %di                      # four sectors loaded by LILO
 244         subw    %si, %si
 245         pushw   %cs
 246         popw    %es
 247         movw    $SYSSEG, %ax
 248         movw    %ax, %ds
 249         rep
 250         movsw
 251         movw    %cs, %ax                        # aka SETUPSEG
 252         movw    %ax, %ds
 253         cmpw    $SIG1, setup_sig1
 254         jne     no_sig
 255
 256         cmpw    $SIG2, setup_sig2
 257         jne     no_sig
 258
 259         jmp     good_sig
 260
 261 no_sig:
 262         lea     no_sig_mess, %si
 263         call    prtstr
 264
 265 no_sig_loop:
 266         hlt
 267         jmp     no_sig_loop
 268
 269 good_sig:
 270         movw    %cs, %ax                        # aka SETUPSEG
 271         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 272         movw    %ax, %ds
 273 # Check if an old loader tries to load a big-kernel
 274         testb   $LOADED_HIGH, %cs:loadflags     # Do we have a big kernel?
 275         jz      loader_ok                       # No, no danger for old loaders.
 276
 277         cmpb    $0, %cs:type_of_loader          # Do we have a loader that
 278                                                 # can deal with us?
 279         jnz     loader_ok                       # Yes, continue.
 280
 281         pushw   %cs                             # No, we have an old loader,
 282         popw    %ds                             # die.
 283         lea     loader_panic_mess, %si
 284         call    prtstr
 285
 286         jmp     no_sig_loop
 287
 288 loader_panic_mess: .string "Wrong loader, giving up..."
 289
 290 loader_ok:
 291 # Get memory size (extended mem, kB)
 292
 293         xorl    %eax, %eax
 294         movl    %eax, (0x1e0)
 295 #ifndef STANDARD_MEMORY_BIOS_CALL
 296         movb    %al, (E820NR)
 297 # Try three different memory detection schemes.  First, try
 298 # e820h, which lets us assemble a memory map, then try e801h,
 299 # which returns a 32-bit memory size, and finally 88h, which
 300 # returns 0-64m
 301
 302 # method E820H:
 303 # the memory map from hell.  e820h returns memory classified into
 304 # a whole bunch of different types, and allows memory holes and
 305 # everything.  We scan through this memory map and build a list
 306 # of the first 32 memory areas, which we return at [E820MAP].
 307 # This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.
 308
 309 #define SMAP  0x534d4150
 310
 311 meme820:
 312         xorl    %ebx, %ebx                      # continuation counter
 313         movw    $E820MAP, %di                   # point into the whitelist
 314                                                 # so we can have the bios
 315                                                 # directly write into it.
 316
 317 jmpe820:
 318         movl    $0x0000e820, %eax               # e820, upper word zeroed
 319         movl    $SMAP, %edx                     # ascii 'SMAP'
 320         movl    $20, %ecx                       # size of the e820rec
 321         pushw   %ds                             # data record.
 322         popw    %es
 323         int     $0x15                           # make the call
 324         jc      bail820                         # fall to e801 if it fails
 325
 326         cmpl    $SMAP, %eax                     # check the return is `SMAP'
 327         jne     bail820                         # fall to e801 if it fails
 328
 329 #       cmpl    $1, 16(%di)                     # is this usable memory?
 330 #       jne     again820
 331
 332         # If this is usable memory, we save it by simply advancing %di by
 333         # sizeof(e820rec).
 334         #
 335 good820:
 336         movb    (E820NR), %al                   # up to 32 entries
 337         cmpb    $E820MAX, %al
 338         jnl     bail820
 339
 340         incb    (E820NR)
 341         movw    %di, %ax
 342         addw    $20, %ax
 343         movw    %ax, %di
 344 again820:
 345         cmpl    $0, %ebx                        # check to see if
 346         jne     jmpe820                         # %ebx is set to EOF
 347 bail820:
 348
 349
 350 # method E801H:
 351 # memory size is in 1k chunksizes, to avoid confusing loadlin.
 352 # we store the 0xe801 memory size in a completely different place,
 353 # because it will most likely be longer than 16 bits.
 354 # (use 1e0 because that's what Larry Augustine uses in his
 355 # alternative new memory detection scheme, and it's sensible
 356 # to write everything into the same place.)
 357
 358 meme801:
 359         stc                                     # fix to work around buggy
 360         xorw    %cx,%cx                         # BIOSes which dont clear/set
 361         xorw    %dx,%dx                         # carry on pass/error of
 362                                                 # e801h memory size call
 363                                                 # or merely pass cx,dx though
 364                                                 # without changing them.
 365         movw    $0xe801, %ax
 366         int     $0x15
 367         jc      mem88
 368
 369         cmpw    $0x0, %cx                       # Kludge to handle BIOSes
 370         jne     e801usecxdx                     # which report their extended
 371         cmpw    $0x0, %dx                       # memory in AX/BX rather than
 372         jne     e801usecxdx                     # CX/DX.  The spec I have read
 373         movw    %ax, %cx                        # seems to indicate AX/BX
 374         movw    %bx, %dx                        # are more reasonable anyway...
 375
 376 e801usecxdx:
 377         andl    $0xffff, %edx                   # clear sign extend
 378         shll    $6, %edx                        # and go from 64k to 1k chunks
 379         movl    %edx, (0x1e0)                   # store extended memory size
 380         andl    $0xffff, %ecx                   # clear sign extend
 381         addl    %ecx, (0x1e0)                   # and add lower memory into
 382                                                 # total size.
 383
 384 # Ye Olde Traditional Methode.  Returns the memory size (up to 16mb or
 385 # 64mb, depending on the bios) in ax.
 386 mem88:
 387
 388 #endif
 389         movb    $0x88, %ah
 390         int     $0x15
 391         movw    %ax, (2)
 392
 393 # Set the keyboard repeat rate to the max
 394         movw    $0x0305, %ax
 395         xorw    %bx, %bx
 396         int     $0x16
 397
 398 # Check for video adapter and its parameters and allow the
 399 # user to browse video modes.
 400         call    video                           # NOTE: we need %ds pointing
 401                                                 # to bootsector
 402
 403 # Get hd0 data...
 404         xorw    %ax, %ax
 405         movw    %ax, %ds
 406         ldsw    (4 * 0x41), %si
 407         movw    %cs, %ax                        # aka SETUPSEG
 408         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 409         pushw   %ax
 410         movw    %ax, %es
 411         movw    $0x0080, %di
 412         movw    $0x10, %cx
 413         pushw   %cx
 414         cld
 415         rep
 416         movsb
 417 # Get hd1 data...
 418         xorw    %ax, %ax
 419         movw    %ax, %ds
 420         ldsw    (4 * 0x46), %si
 421         popw    %cx
 422         popw    %es
 423         movw    $0x0090, %di
 424         rep
 425         movsb
 426 # Check that there IS a hd1 :-)
 427         movw    $0x01500, %ax
 428         movb    $0x81, %dl
 429         int     $0x13
 430         jc      no_disk1
 431
 432         cmpb    $3, %ah
 433         je      is_disk1
 434
 435 no_disk1:
 436         movw    %cs, %ax                        # aka SETUPSEG
 437         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 438         movw    %ax, %es
 439         movw    $0x0090, %di
 440         movw    $0x10, %cx
 441         xorw    %ax, %ax
 442         cld
 443         rep
 444         stosb
 445 is_disk1:
 446 # check for Micro Channel (MCA) bus
 447         movw    %cs, %ax                        # aka SETUPSEG
 448         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 449         movw    %ax, %ds
 450         xorw    %ax, %ax
 451         movw    %ax, (0xa0)                     # set table length to 0
 452         movb    $0xc0, %ah
 453         stc
 454         int     $0x15                           # moves feature table to es:bx
 455         jc      no_mca
 456
 457         pushw   %ds
 458         movw    %es, %ax
 459         movw    %ax, %ds
 460         movw    %cs, %ax                        # aka SETUPSEG
 461         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 462         movw    %ax, %es
 463         movw    %bx, %si
 464         movw    $0xa0, %di
 465         movw    (%si), %cx
 466         addw    $2, %cx                         # table length is a short
 467         cmpw    $0x10, %cx
 468         jc      sysdesc_ok
 469
 470         movw    $0x10, %cx                      # we keep only first 16 bytes
 471 sysdesc_ok:
 472         rep
 473         movsb
 474         popw    %ds
 475 no_mca:
 476 #ifdef CONFIG_X86_VOYAGER
 477         movb    $0xff, 0x40     # flag on config found
 478         movb    $0xc0, %al
 479         mov     $0xff, %ah
 480         int     $0x15           # put voyager config info at es:di
 481         jc      no_voyager
 482         movw    $0x40, %si      # place voyager info in apm table
 483         cld
 484         movw    $7, %cx
 485 voyager_rep:
 486         movb    %es:(%di), %al
 487         movb    %al,(%si)
 488         incw    %di
 489         incw    %si
 490         decw    %cx
 491         jnz     voyager_rep
 492 no_voyager:
 493 #endif
 494 # Check for PS/2 pointing device
 495         movw    %cs, %ax                        # aka SETUPSEG
 496         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 497         movw    %ax, %ds
 498         movw    $0, (0x1ff)                     # default is no pointing device
 499         int     $0x11                           # int 0x11: equipment list
 500         testb   $0x04, %al                      # check if mouse installed
 501         jz      no_psmouse
 502
 503         movw    $0xAA, (0x1ff)                  # device present
 504 no_psmouse:
 505
 506 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
 507         movl    $0x0000E980, %eax               # IST Support
 508         movl    $0x47534943, %edx               # Request value
 509         int     $0x15
 510
 511         movl    %eax, (96)
 512         movl    %ebx, (100)
 513         movl    %ecx, (104)
 514         movl    %edx, (108)
 515 #endif
 516
 517 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 518 # Then check for an APM BIOS...
 519                                                 # %ds points to the bootsector
 520         movw    $0, 0x40                        # version = 0 means no APM BIOS
 521         movw    $0x05300, %ax                   # APM BIOS installation check
 522         xorw    %bx, %bx
 523         int     $0x15
 524         jc      done_apm_bios                   # Nope, no APM BIOS
 525
 526         cmpw    $0x0504d, %bx                   # Check for "PM" signature
 527         jne     done_apm_bios                   # No signature, no APM BIOS
 528
 529         andw    $0x02, %cx                      # Is 32 bit supported?
 530         je      done_apm_bios                   # No 32-bit, no (good) APM BIOS
 531
 532         movw    $0x05304, %ax                   # Disconnect first just in case
 533         xorw    %bx, %bx
 534         int     $0x15                           # ignore return code
 535         movw    $0x05303, %ax                   # 32 bit connect
 536         xorl    %ebx, %ebx
 537         xorw    %cx, %cx                        # paranoia :-)
 538         xorw    %dx, %dx                        #   ...
 539         xorl    %esi, %esi                      #   ...
 540         xorw    %di, %di                        #   ...
 541         int     $0x15
 542         jc      no_32_apm_bios                  # Ack, error.
 543
 544         movw    %ax,  (66)                      # BIOS code segment
 545         movl    %ebx, (68)                      # BIOS entry point offset
 546         movw    %cx,  (72)                      # BIOS 16 bit code segment
 547         movw    %dx,  (74)                      # BIOS data segment
 548         movl    %esi, (78)                      # BIOS code segment lengths
 549         movw    %di,  (82)                      # BIOS data segment length
 550 # Redo the installation check as the 32 bit connect
 551 # modifies the flags returned on some BIOSs
 552         movw    $0x05300, %ax                   # APM BIOS installation check
 553         xorw    %bx, %bx
 554         xorw    %cx, %cx                        # paranoia
 555         int     $0x15
 556         jc      apm_disconnect                  # error -> shouldn't happen
 557
 558         cmpw    $0x0504d, %bx                   # check for "PM" signature
 559         jne     apm_disconnect                  # no sig -> shouldn't happen
 560
 561         movw    %ax, (64)                       # record the APM BIOS version
 562         movw    %cx, (76)                       # and flags
 563         jmp     done_apm_bios
 564
 565 apm_disconnect:                                 # Tidy up
 566         movw    $0x05304, %ax                   # Disconnect
 567         xorw    %bx, %bx
 568         int     $0x15                           # ignore return code
 569
 570         jmp     done_apm_bios
 571
 572 no_32_apm_bios:
 573         andw    $0xfffd, (76)                   # remove 32 bit support bit
 574 done_apm_bios:
 575 #endif
 576
 577 #include "edd.S"
 578
 579 # Now we want to move to protected mode ...
 580         cmpw    $0, %cs:realmode_swtch
 581         jz      rmodeswtch_normal
 582
 583         lcall   *%cs:realmode_swtch
 584
 585         jmp     rmodeswtch_end
 586
 587 rmodeswtch_normal:
 588         pushw   %cs
 589         call    default_switch
 590
 591 rmodeswtch_end:
 592 # we get the code32 start address and modify the below 'jmpi'
 593 # (loader may have changed it)
 594         movl    %cs:code32_start, %eax
 595         movl    %eax, %cs:code32
 596
 597 # Now we move the system to its rightful place ... but we check if we have a
 598 # big-kernel. In that case we *must* not move it ...
 599         testb   $LOADED_HIGH, %cs:loadflags
 600         jz      do_move0                        # .. then we have a normal low
 601                                                 # loaded zImage
 602                                                 # .. or else we have a high
 603                                                 # loaded bzImage
 604         jmp     end_move                        # ... and we skip moving
 605
 606 do_move0:
 607         movw    $0x100, %ax                     # start of destination segment
 608         movw    %cs, %bp                        # aka SETUPSEG
 609         subw    $DELTA_INITSEG, %bp             # aka INITSEG
 610         movw    %cs:start_sys_seg, %bx          # start of source segment
 611         cld
 612 do_move:
 613         movw    %ax, %es                        # destination segment
 614         incb    %ah                             # instead of add ax,#0x100
 615         movw    %bx, %ds                        # source segment
 616         addw    $0x100, %bx
 617         subw    %di, %di
 618         subw    %si, %si
 619         movw    $0x800, %cx
 620         rep
 621         movsw
 622         cmpw    %bp, %bx                        # assume start_sys_seg > 0x200,
 623                                                 # so we will perhaps read one
 624                                                 # page more than needed, but
 625                                                 # never overwrite INITSEG
 626                                                 # because destination is a
 627                                                 # minimum one page below source
 628         jb      do_move
 629
 630 end_move:
 631 # then we load the segment descriptors
 632         movw    %cs, %ax                        # aka SETUPSEG
 633         movw    %ax, %ds
 634
 635 # Check whether we need to be downward compatible with version <=201
 636         cmpl    $0, cmd_line_ptr
 637         jne     end_move_self           # loader uses version >=202 features
 638         cmpb    $0x20, type_of_loader
 639         je      end_move_self           # bootsect loader, we know of it
 640
 641 # Boot loader doesnt support boot protocol version 2.02.
 642 # If we have our code not at 0x90000, we need to move it there now.
 643 # We also then need to move the params behind it (commandline)
 644 # Because we would overwrite the code on the current IP, we move
 645 # it in two steps, jumping high after the first one.
 646         movw    %cs, %ax
 647         cmpw    $SETUPSEG, %ax
 648         je      end_move_self
 649
 650         cli                                     # make sure we really have
 651                                                 # interrupts disabled !
 652                                                 # because after this the stack
 653                                                 # should not be used
 654         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 655         movw    %ss, %dx
 656         cmpw    %ax, %dx
 657         jb      move_self_1
 658
 659         addw    $INITSEG, %dx
 660         subw    %ax, %dx                        # this will go into %ss after
 661                                                 # the move
 662 move_self_1:
 663         movw    %ax, %ds
 664         movw    $INITSEG, %ax                   # real INITSEG
 665         movw    %ax, %es
 666         movw    %cs:setup_move_size, %cx
 667         std                                     # we have to move up, so we use
 668                                                 # direction down because the
 669                                                 # areas may overlap
 670         movw    %cx, %di
 671         decw    %di
 672         movw    %di, %si
 673         subw    $move_self_here+0x200, %cx
 674         rep
 675         movsb
 676         ljmp    $SETUPSEG, $move_self_here
 677
 678 move_self_here:
 679         movw    $move_self_here+0x200, %cx
 680         rep
 681         movsb
 682         movw    $SETUPSEG, %ax
 683         movw    %ax, %ds
 684         movw    %dx, %ss
 685 end_move_self:                                  # now we are at the right place
 686
 687 #
 688 # Enable A20.  This is at the very best an annoying procedure.
 689 # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
 690 # AMD Elan bug fix by Robert Schwebel.
 691 #
 692
 693 #if defined(CONFIG_X86_ELAN)
 694         movb $0x02, %al                 # alternate A20 gate
 695         outb %al, $0x92                 # this works on SC410/SC520
 696 a20_elan_wait:
 697         call a20_test
 698         jz a20_elan_wait
 699         jmp a20_done
 700 #endif
 701
 702
 703 A20_TEST_LOOPS          =  32           # Iterations per wait
 704 A20_ENABLE_LOOPS        = 255           # Total loops to try
 705
 706
 707 #ifndef CONFIG_X86_VOYAGER
 708 a20_try_loop:
 709
 710         # First, see if we are on a system with no A20 gate.
 711 a20_none:
 712         call    a20_test
 713         jnz     a20_done
 714
 715         # Next, try the BIOS (INT 0x15, AX=0x2401)
 716 a20_bios:
 717         movw    $0x2401, %ax
 718         pushfl                                  # Be paranoid about flags
 719         int     $0x15
 720         popfl
 721
 722         call    a20_test
 723         jnz     a20_done
 724
 725         # Try enabling A20 through the keyboard controller
 726 #endif /* CONFIG_X86_VOYAGER */
 727 a20_kbc:
 728         call    empty_8042
 729
 730 #ifndef CONFIG_X86_VOYAGER
 731         call    a20_test                        # Just in case the BIOS worked
 732         jnz     a20_done                        # but had a delayed reaction.
 733 #endif
 734
 735         movb    $0xD1, %al                      # command write
 736         outb    %al, $0x64
 737         call    empty_8042
 738
 739         movb    $0xDF, %al                      # A20 on
 740         outb    %al, $0x60
 741         call    empty_8042
 742
 743 #ifndef CONFIG_X86_VOYAGER
 744         # Wait until a20 really *is* enabled; it can take a fair amount of
 745         # time on certain systems; Toshiba Tecras are known to have this
 746         # problem.
 747 a20_kbc_wait:
 748         xorw    %cx, %cx
 749 a20_kbc_wait_loop:
 750         call    a20_test
 751         jnz     a20_done
 752         loop    a20_kbc_wait_loop
 753
 754         # Final attempt: use "configuration port A"
 755 a20_fast:
 756         inb     $0x92, %al                      # Configuration Port A
 757         orb     $0x02, %al                      # "fast A20" version
 758         andb    $0xFE, %al                      # don't accidentally reset
 759         outb    %al, $0x92
 760
 761         # Wait for configuration port A to take effect
 762 a20_fast_wait:
 763         xorw    %cx, %cx
 764 a20_fast_wait_loop:
 765         call    a20_test
 766         jnz     a20_done
 767         loop    a20_fast_wait_loop
 768
 769         # A20 is still not responding.  Try frobbing it again.
 770         #
 771         decb    (a20_tries)
 772         jnz     a20_try_loop
 773
 774         movw    $a20_err_msg, %si
 775         call    prtstr
 776
 777 a20_die:
 778         hlt
 779         jmp     a20_die
 780
 781 a20_tries:
 782         .byte   A20_ENABLE_LOOPS
 783
 784 a20_err_msg:
 785         .ascii  "linux: fatal error: A20 gate not responding!"
 786         .byte   13, 10, 0
 787
 788         # If we get here, all is good
 789 a20_done:
 790
 791 #endif /* CONFIG_X86_VOYAGER */
 792 # set up gdt and idt
 793         lidt    idt_48                          # load idt with 0,0
 794         xorl    %eax, %eax                      # Compute gdt_base
 795         movw    %ds, %ax                        # (Convert %ds:gdt to a linear ptr)
 796         shll    $4, %eax
 797         addl    $gdt, %eax
 798         movl    %eax, (gdt_48+2)
 799         lgdt    gdt_48                          # load gdt with whatever is
 800                                                 # appropriate
 801
 802 # make sure any possible coprocessor is properly reset..
 803         xorw    %ax, %ax
 804         outb    %al, $0xf0
 805         call    delay
 806
 807         outb    %al, $0xf1
 808         call    delay
 809
 810 # well, that went ok, I hope. Now we mask all interrupts - the rest
 811 # is done in init_IRQ().
 812         movb    $0xFF, %al                      # mask all interrupts for now
 813         outb    %al, $0xA1
 814         call    delay
 815
 816         movb    $0xFB, %al                      # mask all irq's but irq2 which
 817         outb    %al, $0x21                      # is cascaded
 818
 819 # Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
 820 # need no steenking BIOS anyway (except for the initial loading :-).
 821 # The BIOS-routine wants lots of unnecessary data, and it's less
 822 # "interesting" anyway. This is how REAL programmers do it.
 823 #
 824 # Well, now's the time to actually move into protected mode. To make
 825 # things as simple as possible, we do no register set-up or anything,
 826 # we let the gnu-compiled 32-bit programs do that. We just jump to
 827 # absolute address 0x1000 (or the loader supplied one),
 828 # in 32-bit protected mode.
 829 #
 830 # Note that the short jump isn't strictly needed, although there are
 831 # reasons why it might be a good idea. It won't hurt in any case.
 832         movw    $1, %ax                         # protected mode (PE) bit
 833         lmsw    %ax                             # This is it!
 834         jmp     flush_instr
 835
 836 flush_instr:
 837         xorw    %bx, %bx                        # Flag to indicate a boot
 838         xorl    %esi, %esi                      # Pointer to real-mode code
 839         movw    %cs, %si
 840         subw    $DELTA_INITSEG, %si
 841         shll    $4, %esi                        # Convert to 32-bit pointer
 842
 843 # jump to startup_32 in arch/i386/boot/compressed/head.S
 844 #
 845 # NOTE: For high loaded big kernels we need a
 846 #       jmpi    0x100000,__BOOT_CS
 847 #
 848 #       but we yet haven't reloaded the CS register, so the default size
 849 #       of the target offset still is 16 bit.
 850 #       However, using an operand prefix (0x66), the CPU will properly
 851 #       take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
 852 #       Manual, Mixing 16-bit and 32-bit code, page 16-6)
 853
 854         .byte 0x66, 0xea                        # prefix + jmpi-opcode
 855 code32: .long   0x1000                          # will be set to 0x100000
 856                                                 # for big kernels
 857         .word   __BOOT_CS
 858
 859 # Here's a bunch of information about your current kernel..
 860 kernel_version: .ascii  UTS_RELEASE
 861                 .ascii  " ("
 862                 .ascii  LINUX_COMPILE_BY
 863                 .ascii  "@"
 864                 .ascii  LINUX_COMPILE_HOST
 865                 .ascii  ") "
 866                 .ascii  UTS_VERSION
 867                 .byte   0
 868
 869 # This is the default real mode switch routine.
 870 # to be called just before protected mode transition
 871 default_switch:
 872         cli                                     # no interrupts allowed !
 873         movb    $0x80, %al                      # disable NMI for bootup
 874                                                 # sequence
 875         outb    %al, $0x70
 876         lret
 877
 878
 879 #ifndef CONFIG_X86_VOYAGER
 880 # This routine tests whether or not A20 is enabled.  If so, it
 881 # exits with zf = 0.
 882 #
 883 # The memory address used, 0x200, is the int $0x80 vector, which
 884 # should be safe.
 885
 886 A20_TEST_ADDR = 4*0x80
 887
 888 a20_test:
 889         pushw   %cx
 890         pushw   %ax
 891         xorw    %cx, %cx
 892         movw    %cx, %fs                        # Low memory
 893         decw    %cx
 894         movw    %cx, %gs                        # High memory area
 895         movw    $A20_TEST_LOOPS, %cx
 896         movw    %fs:(A20_TEST_ADDR), %ax
 897         pushw   %ax
 898 a20_test_wait:
 899         incw    %ax
 900         movw    %ax, %fs:(A20_TEST_ADDR)
 901         call    delay                           # Serialize and make delay constant
 902         cmpw    %gs:(A20_TEST_ADDR+0x10), %ax
 903         loope   a20_test_wait
 904
 905         popw    %fs:(A20_TEST_ADDR)
 906         popw    %ax
 907         popw    %cx
 908         ret
 909
 910 #endif /* CONFIG_X86_VOYAGER */
 911
 912 # This routine checks that the keyboard command queue is empty
 913 # (after emptying the output buffers)
 914 #
 915 # Some machines have delusions that the keyboard buffer is always full
 916 # with no keyboard attached...
 917 #
 918 # If there is no keyboard controller, we will usually get 0xff
 919 # to all the reads.  With each IO taking a microsecond and
 920 # a timeout of 100,000 iterations, this can take about half a
 921 # second ("delay" == outb to port 0x80). That should be ok,
 922 # and should also be plenty of time for a real keyboard controller
 923 # to empty.
 924 #
 925
 926 empty_8042:
 927         pushl   %ecx
 928         movl    $100000, %ecx
 929
 930 empty_8042_loop:
 931         decl    %ecx
 932         jz      empty_8042_end_loop
 933
 934         call    delay
 935
 936         inb     $0x64, %al                      # 8042 status port
 937         testb   $1, %al                         # output buffer?
 938         jz      no_output
 939
 940         call    delay
 941         inb     $0x60, %al                      # read it
 942         jmp     empty_8042_loop
 943
 944 no_output:
 945         testb   $2, %al                         # is input buffer full?
 946         jnz     empty_8042_loop                 # yes - loop
 947 empty_8042_end_loop:
 948         popl    %ecx
 949         ret
 950
 951 # Read the cmos clock. Return the seconds in al
 952 gettime:
 953         pushw   %cx
 954         movb    $0x02, %ah
 955         int     $0x1a
 956         movb    %dh, %al                        # %dh contains the seconds
 957         andb    $0x0f, %al
 958         movb    %dh, %ah
 959         movb    $0x04, %cl
 960         shrb    %cl, %ah
 961         aad
 962         popw    %cx
 963         ret
 964
 965 # Delay is needed after doing I/O
 966 delay:
 967         outb    %al,$0x80
 968         ret
 969
 970 # Descriptor tables
 971 #
 972 # NOTE: The intel manual says gdt should be sixteen bytes aligned for
 973 # efficiency reasons.  However, there are machines which are known not
 974 # to boot with misaligned GDTs, so alter this at your peril!  If you alter
 975 # GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
 976 # empty GDT entries (one for NULL and one reserved).
 977 #
 978 # NOTE: On some CPUs, the GDT must be 8 byte aligned.  This is
 979 # true for the Voyager Quad CPU card which will not boot without
 980 # This directive.  16 byte aligment is recommended by intel.
 981 #
 982         .align 16
 983 gdt:
 984         .fill GDT_ENTRY_BOOT_CS,8,0
 985
 986         .word   0xFFFF                          # 4Gb - (0x100000*0x1000 = 4Gb)
 987         .word   0                               # base address = 0
 988         .word   0x9A00                          # code read/exec
 989         .word   0x00CF                          # granularity = 4096, 386
 990                                                 #  (+5th nibble of limit)
 991
 992         .word   0xFFFF                          # 4Gb - (0x100000*0x1000 = 4Gb)
 993         .word   0                               # base address = 0
 994         .word   0x9200                          # data read/write
 995         .word   0x00CF                          # granularity = 4096, 386
 996                                                 #  (+5th nibble of limit)
 997 gdt_end:
 998         .align  4
 999
1000         .word   0                               # alignment byte
1001 idt_48:
1002         .word   0                               # idt limit = 0
1003         .word   0, 0                            # idt base = 0L
1004
1005         .word   0                               # alignment byte
1006 gdt_48:
1007         .word   gdt_end - gdt - 1               # gdt limit
1008         .word   0, 0                            # gdt base (filled in later)
1009
1010 # Include video setup & detection code
1011
1012 #include "video.S"
1013
1014 # Setup signature -- must be last
1015 setup_sig1:     .word   SIG1
1016 setup_sig2:     .word   SIG2
1017
1018 # After this point, there is some free space which is used by the video mode
1019 # handling code to store the temporary mode table (not used by the kernel).
1020
1021 modelist:
1022
1023 .text
1024 endtext:
1025 .data
1026 enddata:
1027 .bss
1028 endbss: