arch/i386/boot/setup.S

   1 /*
   2  *      setup.S         Copyright (C) 1991, 1992 Linus Torvalds
   3  *
   4  * setup.s is responsible for getting the system data from the BIOS,
   5  * and putting them into the appropriate places in system memory.
   6  * both setup.s and system has been loaded by the bootblock.
   7  *
   8  * This code asks the bios for memory/disk/other parameters, and
   9  * puts them in a "safe" place: 0x90000-0x901FF, ie where the
  10  * boot-block used to be. It is then up to the protected mode
  11  * system to read them from there before the area is overwritten
  12  * for buffer-blocks.
  13  *
  14  * Move PS/2 aux init code to psaux.c
  15  * (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
  16  *
  17  * some changes and additional features by Christoph Niemann,
  18  * March 1993/June 1994 (Christoph.Niemann@linux.org)
  19  *
  20  * add APM BIOS checking by Stephen Rothwell, May 1994
  21  * (sfr@canb.auug.org.au)
  22  *
  23  * High load stuff, initrd support and position independency
  24  * by Hans Lermen & Werner Almesberger, February 1996
  25  * <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
  26  *
  27  * Video handling moved to video.S by Martin Mares, March 1996
  28  * <mj@k332.feld.cvut.cz>
  29  *
  30  * Extended memory detection scheme retwiddled by orc@pell.chi.il.us (david
  31  * parsons) to avoid loadlin confusion, July 1997
  32  *
  33  * Transcribed from Intel (as86) -> AT&T (gas) by Chris Noe, May 1999.
  34  * <stiker@northlink.com>
  35  *
  36  * Fix to work around buggy BIOSes which don't use carry bit correctly
  37  * and/or report extended memory in CX/DX for e801h memory size detection
  38  * call.  As a result the kernel got wrong figures.  The int15/e801h docs
  39  * from Ralf Brown interrupt list seem to indicate AX/BX should be used
  40  * anyway.  So to avoid breaking many machines (presumably there was a reason
  41  * to orginally use CX/DX instead of AX/BX), we do a kludge to see
  42  * if CX/DX have been changed in the e801 call and if so use AX/BX .
  43  * Michael Miller, April 2001 <michaelm@mjmm.org>
  44  *
  45  * New A20 code ported from SYSLINUX by H. Peter Anvin. AMD Elan bugfixes
  46  * by Robert Schwebel, December 2001 <robert@schwebel.de>
  47  */
  48
  49 #include <asm/segment.h>
  50 #include <linux/utsrelease.h>
  51 #include <linux/compile.h>
  52 #include <asm/boot.h>
  53 #include <asm/e820.h>
  54 #include <asm/page.h>
  55
  56 /* Signature words to ensure LILO loaded us right */
  57 #define SIG1    0xAA55
  58 #define SIG2    0x5A5A
  59
  60 INITSEG  = DEF_INITSEG          # 0x9000, we move boot here, out of the way
  61 SYSSEG   = DEF_SYSSEG           # 0x1000, system loaded at 0x10000 (65536).
  62 SETUPSEG = DEF_SETUPSEG         # 0x9020, this is the current segment
  63                                 # ... and the former contents of CS
  64
  65 DELTA_INITSEG = SETUPSEG - INITSEG      # 0x0020
  66
  67 .code16
  68 .globl begtext, begdata, begbss, endtext, enddata, endbss
  69
  70 .text
  71 begtext:
  72 .data
  73 begdata:
  74 .bss
  75 begbss:
  76 .text
  77
  78 start:
  79         jmp     trampoline
  80
  81 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
  82
  83                 .ascii  "HdrS"          # header signature
  84                 .word   0x0204          # header version number (>= 0x0105)
  85                                         # or else old loadlin-1.5 will fail)
  86 realmode_swtch: .word   0, 0            # default_switch, SETUPSEG
  87 start_sys_seg:  .word   SYSSEG
  88                 .word   kernel_version  # pointing to kernel version string
  89                                         # above section of header is compatible
  90                                         # with loadlin-1.5 (header v1.5). Don't
  91                                         # change it.
  92
  93 type_of_loader: .byte   0               # = 0, old one (LILO, Loadlin,
  94                                         #      Bootlin, SYSLX, bootsect...)
  95                                         # See Documentation/i386/boot.txt for
  96                                         # assigned ids
  97
  98 # flags, unused bits must be zero (RFU) bit within loadflags
  99 loadflags:
 100 LOADED_HIGH     = 1                     # If set, the kernel is loaded high
 101 CAN_USE_HEAP    = 0x80                  # If set, the loader also has set
 102                                         # heap_end_ptr to tell how much
 103                                         # space behind setup.S can be used for
 104                                         # heap purposes.
 105                                         # Only the loader knows what is free
 106 #ifndef __BIG_KERNEL__
 107                 .byte   0
 108 #else
 109                 .byte   LOADED_HIGH
 110 #endif
 111
 112 setup_move_size: .word  0x8000          # size to move, when setup is not
 113                                         # loaded at 0x90000. We will move setup
 114                                         # to 0x90000 then just before jumping
 115                                         # into the kernel. However, only the
 116                                         # loader knows how much data behind
 117                                         # us also needs to be loaded.
 118
 119 code32_start:                           # here loaders can put a different
 120                                         # start address for 32-bit code.
 121 #ifndef __BIG_KERNEL__
 122                 .long   0x1000          #   0x1000 = default for zImage
 123 #else
 124                 .long   0x100000        # 0x100000 = default for big kernel
 125 #endif
 126
 127 ramdisk_image:  .long   0               # address of loaded ramdisk image
 128                                         # Here the loader puts the 32-bit
 129                                         # address where it loaded the image.
 130                                         # This only will be read by the kernel.
 131
 132 ramdisk_size:   .long   0               # its size in bytes
 133
 134 bootsect_kludge:
 135                 .long   0               # obsolete
 136
 137 heap_end_ptr:   .word   modelist+1024   # (Header version 0x0201 or later)
 138                                         # space from here (exclusive) down to
 139                                         # end of setup code can be used by setup
 140                                         # for local heap purposes.
 141
 142 pad1:           .word   0
 143 cmd_line_ptr:   .long 0                 # (Header version 0x0202 or later)
 144                                         # If nonzero, a 32-bit pointer
 145                                         # to the kernel command line.
 146                                         # The command line should be
 147                                         # located between the start of
 148                                         # setup and the end of low
 149                                         # memory (0xa0000), or it may
 150                                         # get overwritten before it
 151                                         # gets read.  If this field is
 152                                         # used, there is no longer
 153                                         # anything magical about the
 154                                         # 0x90000 segment; the setup
 155                                         # can be located anywhere in
 156                                         # low memory 0x10000 or higher.
 157
 158 ramdisk_max:    .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
 159                                         # (Header version 0x0203 or later)
 160                                         # The highest safe address for
 161                                         # the contents of an initrd
 162
 163 trampoline:     call    start_of_setup
 164                 .align 16
 165                                         # The offset at this point is 0x240
 166                 .space  (0xeff-0x240+1) # E820 & EDD space (ending at 0xeff)
 167 # End of setup header #####################################################
 168
 169 start_of_setup:
 170 # Bootlin depends on this being done early
 171         movw    $0x01500, %ax
 172         movb    $0x81, %dl
 173         int     $0x13
 174
 175 #ifdef SAFE_RESET_DISK_CONTROLLER
 176 # Reset the disk controller.
 177         movw    $0x0000, %ax
 178         movb    $0x80, %dl
 179         int     $0x13
 180 #endif
 181
 182 # Set %ds = %cs, we know that SETUPSEG = %cs at this point
 183         movw    %cs, %ax                # aka SETUPSEG
 184         movw    %ax, %ds
 185 # Check signature at end of setup
 186         cmpw    $SIG1, setup_sig1
 187         jne     bad_sig
 188
 189         cmpw    $SIG2, setup_sig2
 190         jne     bad_sig
 191
 192         jmp     good_sig1
 193
 194 # Routine to print asciiz string at ds:si
 195 prtstr:
 196         lodsb
 197         andb    %al, %al
 198         jz      fin
 199
 200         call    prtchr
 201         jmp     prtstr
 202
 203 fin:    ret
 204
 205 # Space printing
 206 prtsp2: call    prtspc          # Print double space
 207 prtspc: movb    $0x20, %al      # Print single space (note: fall-thru)
 208
 209 # Part of above routine, this one just prints ascii al
 210 prtchr: pushw   %ax
 211         pushw   %cx
 212         movw    $7,%bx
 213         movw    $0x01, %cx
 214         movb    $0x0e, %ah
 215         int     $0x10
 216         popw    %cx
 217         popw    %ax
 218         ret
 219
 220 beep:   movb    $0x07, %al
 221         jmp     prtchr
 222
 223 no_sig_mess: .string    "No setup signature found ..."
 224
 225 good_sig1:
 226         jmp     good_sig
 227
 228 # We now have to find the rest of the setup code/data
 229 bad_sig:
 230         movw    %cs, %ax                        # SETUPSEG
 231         subw    $DELTA_INITSEG, %ax             # INITSEG
 232         movw    %ax, %ds
 233         xorb    %bh, %bh
 234         movb    (497), %bl                      # get setup sect from bootsect
 235         subw    $4, %bx                         # LILO loads 4 sectors of setup
 236         shlw    $8, %bx                         # convert to words (1sect=2^8 words)
 237         movw    %bx, %cx
 238         shrw    $3, %bx                         # convert to segment
 239         addw    $SYSSEG, %bx
 240         movw    %bx, %cs:start_sys_seg
 241 # Move rest of setup code/data to here
 242         movw    $2048, %di                      # four sectors loaded by LILO
 243         subw    %si, %si
 244         pushw   %cs
 245         popw    %es
 246         movw    $SYSSEG, %ax
 247         movw    %ax, %ds
 248         rep
 249         movsw
 250         movw    %cs, %ax                        # aka SETUPSEG
 251         movw    %ax, %ds
 252         cmpw    $SIG1, setup_sig1
 253         jne     no_sig
 254
 255         cmpw    $SIG2, setup_sig2
 256         jne     no_sig
 257
 258         jmp     good_sig
 259
 260 no_sig:
 261         lea     no_sig_mess, %si
 262         call    prtstr
 263
 264 no_sig_loop:
 265         hlt
 266         jmp     no_sig_loop
 267
 268 good_sig:
 269         movw    %cs, %ax                        # aka SETUPSEG
 270         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 271         movw    %ax, %ds
 272 # Check if an old loader tries to load a big-kernel
 273         testb   $LOADED_HIGH, %cs:loadflags     # Do we have a big kernel?
 274         jz      loader_ok                       # No, no danger for old loaders.
 275
 276         cmpb    $0, %cs:type_of_loader          # Do we have a loader that
 277                                                 # can deal with us?
 278         jnz     loader_ok                       # Yes, continue.
 279
 280         pushw   %cs                             # No, we have an old loader,
 281         popw    %ds                             # die.
 282         lea     loader_panic_mess, %si
 283         call    prtstr
 284
 285         jmp     no_sig_loop
 286
 287 loader_panic_mess: .string "Wrong loader, giving up..."
 288
 289 loader_ok:
 290 # Get memory size (extended mem, kB)
 291
 292         xorl    %eax, %eax
 293         movl    %eax, (0x1e0)
 294 #ifndef STANDARD_MEMORY_BIOS_CALL
 295         movb    %al, (E820NR)
 296 # Try three different memory detection schemes.  First, try
 297 # e820h, which lets us assemble a memory map, then try e801h,
 298 # which returns a 32-bit memory size, and finally 88h, which
 299 # returns 0-64m
 300
 301 # method E820H:
 302 # the memory map from hell.  e820h returns memory classified into
 303 # a whole bunch of different types, and allows memory holes and
 304 # everything.  We scan through this memory map and build a list
 305 # of the first 32 memory areas, which we return at [E820MAP].
 306 # This is documented at http://www.acpi.info/, in the ACPI 2.0 specification.
 307
 308 #define SMAP  0x534d4150
 309
 310 meme820:
 311         xorl    %ebx, %ebx                      # continuation counter
 312         movw    $E820MAP, %di                   # point into the whitelist
 313                                                 # so we can have the bios
 314                                                 # directly write into it.
 315
 316 jmpe820:
 317         movl    $0x0000e820, %eax               # e820, upper word zeroed
 318         movl    $SMAP, %edx                     # ascii 'SMAP'
 319         movl    $20, %ecx                       # size of the e820rec
 320         pushw   %ds                             # data record.
 321         popw    %es
 322         int     $0x15                           # make the call
 323         jc      bail820                         # fall to e801 if it fails
 324
 325         cmpl    $SMAP, %eax                     # check the return is `SMAP'
 326         jne     bail820                         # fall to e801 if it fails
 327
 328 #       cmpl    $1, 16(%di)                     # is this usable memory?
 329 #       jne     again820
 330
 331         # If this is usable memory, we save it by simply advancing %di by
 332         # sizeof(e820rec).
 333         #
 334 good820:
 335         movb    (E820NR), %al                   # up to 128 entries
 336         cmpb    $E820MAX, %al
 337         jae     bail820
 338
 339         incb    (E820NR)
 340         movw    %di, %ax
 341         addw    $20, %ax
 342         movw    %ax, %di
 343 again820:
 344         cmpl    $0, %ebx                        # check to see if
 345         jne     jmpe820                         # %ebx is set to EOF
 346 bail820:
 347
 348
 349 # method E801H:
 350 # memory size is in 1k chunksizes, to avoid confusing loadlin.
 351 # we store the 0xe801 memory size in a completely different place,
 352 # because it will most likely be longer than 16 bits.
 353 # (use 1e0 because that's what Larry Augustine uses in his
 354 # alternative new memory detection scheme, and it's sensible
 355 # to write everything into the same place.)
 356
 357 meme801:
 358         stc                                     # fix to work around buggy
 359         xorw    %cx,%cx                         # BIOSes which don't clear/set
 360         xorw    %dx,%dx                         # carry on pass/error of
 361                                                 # e801h memory size call
 362                                                 # or merely pass cx,dx though
 363                                                 # without changing them.
 364         movw    $0xe801, %ax
 365         int     $0x15
 366         jc      mem88
 367
 368         cmpw    $0x0, %cx                       # Kludge to handle BIOSes
 369         jne     e801usecxdx                     # which report their extended
 370         cmpw    $0x0, %dx                       # memory in AX/BX rather than
 371         jne     e801usecxdx                     # CX/DX.  The spec I have read
 372         movw    %ax, %cx                        # seems to indicate AX/BX
 373         movw    %bx, %dx                        # are more reasonable anyway...
 374
 375 e801usecxdx:
 376         andl    $0xffff, %edx                   # clear sign extend
 377         shll    $6, %edx                        # and go from 64k to 1k chunks
 378         movl    %edx, (0x1e0)                   # store extended memory size
 379         andl    $0xffff, %ecx                   # clear sign extend
 380         addl    %ecx, (0x1e0)                   # and add lower memory into
 381                                                 # total size.
 382
 383 # Ye Olde Traditional Methode.  Returns the memory size (up to 16mb or
 384 # 64mb, depending on the bios) in ax.
 385 mem88:
 386
 387 #endif
 388         movb    $0x88, %ah
 389         int     $0x15
 390         movw    %ax, (2)
 391
 392 # Set the keyboard repeat rate to the max
 393         movw    $0x0305, %ax
 394         xorw    %bx, %bx
 395         int     $0x16
 396
 397 # Check for video adapter and its parameters and allow the
 398 # user to browse video modes.
 399         call    video                           # NOTE: we need %ds pointing
 400                                                 # to bootsector
 401
 402 # Get hd0 data...
 403         xorw    %ax, %ax
 404         movw    %ax, %ds
 405         ldsw    (4 * 0x41), %si
 406         movw    %cs, %ax                        # aka SETUPSEG
 407         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 408         pushw   %ax
 409         movw    %ax, %es
 410         movw    $0x0080, %di
 411         movw    $0x10, %cx
 412         pushw   %cx
 413         cld
 414         rep
 415         movsb
 416 # Get hd1 data...
 417         xorw    %ax, %ax
 418         movw    %ax, %ds
 419         ldsw    (4 * 0x46), %si
 420         popw    %cx
 421         popw    %es
 422         movw    $0x0090, %di
 423         rep
 424         movsb
 425 # Check that there IS a hd1 :-)
 426         movw    $0x01500, %ax
 427         movb    $0x81, %dl
 428         int     $0x13
 429         jc      no_disk1
 430
 431         cmpb    $3, %ah
 432         je      is_disk1
 433
 434 no_disk1:
 435         movw    %cs, %ax                        # aka SETUPSEG
 436         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 437         movw    %ax, %es
 438         movw    $0x0090, %di
 439         movw    $0x10, %cx
 440         xorw    %ax, %ax
 441         cld
 442         rep
 443         stosb
 444 is_disk1:
 445 # check for Micro Channel (MCA) bus
 446         movw    %cs, %ax                        # aka SETUPSEG
 447         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 448         movw    %ax, %ds
 449         xorw    %ax, %ax
 450         movw    %ax, (0xa0)                     # set table length to 0
 451         movb    $0xc0, %ah
 452         stc
 453         int     $0x15                           # moves feature table to es:bx
 454         jc      no_mca
 455
 456         pushw   %ds
 457         movw    %es, %ax
 458         movw    %ax, %ds
 459         movw    %cs, %ax                        # aka SETUPSEG
 460         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 461         movw    %ax, %es
 462         movw    %bx, %si
 463         movw    $0xa0, %di
 464         movw    (%si), %cx
 465         addw    $2, %cx                         # table length is a short
 466         cmpw    $0x10, %cx
 467         jc      sysdesc_ok
 468
 469         movw    $0x10, %cx                      # we keep only first 16 bytes
 470 sysdesc_ok:
 471         rep
 472         movsb
 473         popw    %ds
 474 no_mca:
 475 #ifdef CONFIG_X86_VOYAGER
 476         movb    $0xff, 0x40     # flag on config found
 477         movb    $0xc0, %al
 478         mov     $0xff, %ah
 479         int     $0x15           # put voyager config info at es:di
 480         jc      no_voyager
 481         movw    $0x40, %si      # place voyager info in apm table
 482         cld
 483         movw    $7, %cx
 484 voyager_rep:
 485         movb    %es:(%di), %al
 486         movb    %al,(%si)
 487         incw    %di
 488         incw    %si
 489         decw    %cx
 490         jnz     voyager_rep
 491 no_voyager:
 492 #endif
 493 # Check for PS/2 pointing device
 494         movw    %cs, %ax                        # aka SETUPSEG
 495         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 496         movw    %ax, %ds
 497         movw    $0, (0x1ff)                     # default is no pointing device
 498         int     $0x11                           # int 0x11: equipment list
 499         testb   $0x04, %al                      # check if mouse installed
 500         jz      no_psmouse
 501
 502         movw    $0xAA, (0x1ff)                  # device present
 503 no_psmouse:
 504
 505 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)
 506         movl    $0x0000E980, %eax               # IST Support
 507         movl    $0x47534943, %edx               # Request value
 508         int     $0x15
 509
 510         movl    %eax, (96)
 511         movl    %ebx, (100)
 512         movl    %ecx, (104)
 513         movl    %edx, (108)
 514 #endif
 515
 516 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 517 # Then check for an APM BIOS...
 518                                                 # %ds points to the bootsector
 519         movw    $0, 0x40                        # version = 0 means no APM BIOS
 520         movw    $0x05300, %ax                   # APM BIOS installation check
 521         xorw    %bx, %bx
 522         int     $0x15
 523         jc      done_apm_bios                   # Nope, no APM BIOS
 524
 525         cmpw    $0x0504d, %bx                   # Check for "PM" signature
 526         jne     done_apm_bios                   # No signature, no APM BIOS
 527
 528         andw    $0x02, %cx                      # Is 32 bit supported?
 529         je      done_apm_bios                   # No 32-bit, no (good) APM BIOS
 530
 531         movw    $0x05304, %ax                   # Disconnect first just in case
 532         xorw    %bx, %bx
 533         int     $0x15                           # ignore return code
 534         movw    $0x05303, %ax                   # 32 bit connect
 535         xorl    %ebx, %ebx
 536         xorw    %cx, %cx                        # paranoia :-)
 537         xorw    %dx, %dx                        #   ...
 538         xorl    %esi, %esi                      #   ...
 539         xorw    %di, %di                        #   ...
 540         int     $0x15
 541         jc      no_32_apm_bios                  # Ack, error.
 542
 543         movw    %ax,  (66)                      # BIOS code segment
 544         movl    %ebx, (68)                      # BIOS entry point offset
 545         movw    %cx,  (72)                      # BIOS 16 bit code segment
 546         movw    %dx,  (74)                      # BIOS data segment
 547         movl    %esi, (78)                      # BIOS code segment lengths
 548         movw    %di,  (82)                      # BIOS data segment length
 549 # Redo the installation check as the 32 bit connect
 550 # modifies the flags returned on some BIOSs
 551         movw    $0x05300, %ax                   # APM BIOS installation check
 552         xorw    %bx, %bx
 553         xorw    %cx, %cx                        # paranoia
 554         int     $0x15
 555         jc      apm_disconnect                  # error -> shouldn't happen
 556
 557         cmpw    $0x0504d, %bx                   # check for "PM" signature
 558         jne     apm_disconnect                  # no sig -> shouldn't happen
 559
 560         movw    %ax, (64)                       # record the APM BIOS version
 561         movw    %cx, (76)                       # and flags
 562         jmp     done_apm_bios
 563
 564 apm_disconnect:                                 # Tidy up
 565         movw    $0x05304, %ax                   # Disconnect
 566         xorw    %bx, %bx
 567         int     $0x15                           # ignore return code
 568
 569         jmp     done_apm_bios
 570
 571 no_32_apm_bios:
 572         andw    $0xfffd, (76)                   # remove 32 bit support bit
 573 done_apm_bios:
 574 #endif
 575
 576 #include "edd.S"
 577
 578 # Now we want to move to protected mode ...
 579         cmpw    $0, %cs:realmode_swtch
 580         jz      rmodeswtch_normal
 581
 582         lcall   *%cs:realmode_swtch
 583
 584         jmp     rmodeswtch_end
 585
 586 rmodeswtch_normal:
 587         pushw   %cs
 588         call    default_switch
 589
 590 rmodeswtch_end:
 591 # we get the code32 start address and modify the below 'jmpi'
 592 # (loader may have changed it)
 593         movl    %cs:code32_start, %eax
 594         movl    %eax, %cs:code32
 595
 596 # Now we move the system to its rightful place ... but we check if we have a
 597 # big-kernel. In that case we *must* not move it ...
 598         testb   $LOADED_HIGH, %cs:loadflags
 599         jz      do_move0                        # .. then we have a normal low
 600                                                 # loaded zImage
 601                                                 # .. or else we have a high
 602                                                 # loaded bzImage
 603         jmp     end_move                        # ... and we skip moving
 604
 605 do_move0:
 606         movw    $0x100, %ax                     # start of destination segment
 607         movw    %cs, %bp                        # aka SETUPSEG
 608         subw    $DELTA_INITSEG, %bp             # aka INITSEG
 609         movw    %cs:start_sys_seg, %bx          # start of source segment
 610         cld
 611 do_move:
 612         movw    %ax, %es                        # destination segment
 613         incb    %ah                             # instead of add ax,#0x100
 614         movw    %bx, %ds                        # source segment
 615         addw    $0x100, %bx
 616         subw    %di, %di
 617         subw    %si, %si
 618         movw    $0x800, %cx
 619         rep
 620         movsw
 621         cmpw    %bp, %bx                        # assume start_sys_seg > 0x200,
 622                                                 # so we will perhaps read one
 623                                                 # page more than needed, but
 624                                                 # never overwrite INITSEG
 625                                                 # because destination is a
 626                                                 # minimum one page below source
 627         jb      do_move
 628
 629 end_move:
 630 # then we load the segment descriptors
 631         movw    %cs, %ax                        # aka SETUPSEG
 632         movw    %ax, %ds
 633
 634 # Check whether we need to be downward compatible with version <=201
 635         cmpl    $0, cmd_line_ptr
 636         jne     end_move_self           # loader uses version >=202 features
 637         cmpb    $0x20, type_of_loader
 638         je      end_move_self           # bootsect loader, we know of it
 639
 640 # Boot loader doesnt support boot protocol version 2.02.
 641 # If we have our code not at 0x90000, we need to move it there now.
 642 # We also then need to move the params behind it (commandline)
 643 # Because we would overwrite the code on the current IP, we move
 644 # it in two steps, jumping high after the first one.
 645         movw    %cs, %ax
 646         cmpw    $SETUPSEG, %ax
 647         je      end_move_self
 648
 649         cli                                     # make sure we really have
 650                                                 # interrupts disabled !
 651                                                 # because after this the stack
 652                                                 # should not be used
 653         subw    $DELTA_INITSEG, %ax             # aka INITSEG
 654         movw    %ss, %dx
 655         cmpw    %ax, %dx
 656         jb      move_self_1
 657
 658         addw    $INITSEG, %dx
 659         subw    %ax, %dx                        # this will go into %ss after
 660                                                 # the move
 661 move_self_1:
 662         movw    %ax, %ds
 663         movw    $INITSEG, %ax                   # real INITSEG
 664         movw    %ax, %es
 665         movw    %cs:setup_move_size, %cx
 666         std                                     # we have to move up, so we use
 667                                                 # direction down because the
 668                                                 # areas may overlap
 669         movw    %cx, %di
 670         decw    %di
 671         movw    %di, %si
 672         subw    $move_self_here+0x200, %cx
 673         rep
 674         movsb
 675         ljmp    $SETUPSEG, $move_self_here
 676
 677 move_self_here:
 678         movw    $move_self_here+0x200, %cx
 679         rep
 680         movsb
 681         movw    $SETUPSEG, %ax
 682         movw    %ax, %ds
 683         movw    %dx, %ss
 684 end_move_self:                                  # now we are at the right place
 685
 686 #
 687 # Enable A20.  This is at the very best an annoying procedure.
 688 # A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin.
 689 # AMD Elan bug fix by Robert Schwebel.
 690 #
 691
 692 #if defined(CONFIG_X86_ELAN)
 693         movb $0x02, %al                 # alternate A20 gate
 694         outb %al, $0x92                 # this works on SC410/SC520
 695 a20_elan_wait:
 696         call a20_test
 697         jz a20_elan_wait
 698         jmp a20_done
 699 #endif
 700
 701
 702 A20_TEST_LOOPS          =  32           # Iterations per wait
 703 A20_ENABLE_LOOPS        = 255           # Total loops to try
 704
 705
 706 #ifndef CONFIG_X86_VOYAGER
 707 a20_try_loop:
 708
 709         # First, see if we are on a system with no A20 gate.
 710 a20_none:
 711         call    a20_test
 712         jnz     a20_done
 713
 714         # Next, try the BIOS (INT 0x15, AX=0x2401)
 715 a20_bios:
 716         movw    $0x2401, %ax
 717         pushfl                                  # Be paranoid about flags
 718         int     $0x15
 719         popfl
 720
 721         call    a20_test
 722         jnz     a20_done
 723
 724         # Try enabling A20 through the keyboard controller
 725 #endif /* CONFIG_X86_VOYAGER */
 726 a20_kbc:
 727         call    empty_8042
 728
 729 #ifndef CONFIG_X86_VOYAGER
 730         call    a20_test                        # Just in case the BIOS worked
 731         jnz     a20_done                        # but had a delayed reaction.
 732 #endif
 733
 734         movb    $0xD1, %al                      # command write
 735         outb    %al, $0x64
 736         call    empty_8042
 737
 738         movb    $0xDF, %al                      # A20 on
 739         outb    %al, $0x60
 740         call    empty_8042
 741
 742 #ifndef CONFIG_X86_VOYAGER
 743         # Wait until a20 really *is* enabled; it can take a fair amount of
 744         # time on certain systems; Toshiba Tecras are known to have this
 745         # problem.
 746 a20_kbc_wait:
 747         xorw    %cx, %cx
 748 a20_kbc_wait_loop:
 749         call    a20_test
 750         jnz     a20_done
 751         loop    a20_kbc_wait_loop
 752
 753         # Final attempt: use "configuration port A"
 754 a20_fast:
 755         inb     $0x92, %al                      # Configuration Port A
 756         orb     $0x02, %al                      # "fast A20" version
 757         andb    $0xFE, %al                      # don't accidentally reset
 758         outb    %al, $0x92
 759
 760         # Wait for configuration port A to take effect
 761 a20_fast_wait:
 762         xorw    %cx, %cx
 763 a20_fast_wait_loop:
 764         call    a20_test
 765         jnz     a20_done
 766         loop    a20_fast_wait_loop
 767
 768         # A20 is still not responding.  Try frobbing it again.
 769         #
 770         decb    (a20_tries)
 771         jnz     a20_try_loop
 772
 773         movw    $a20_err_msg, %si
 774         call    prtstr
 775
 776 a20_die:
 777         hlt
 778         jmp     a20_die
 779
 780 a20_tries:
 781         .byte   A20_ENABLE_LOOPS
 782
 783 a20_err_msg:
 784         .ascii  "linux: fatal error: A20 gate not responding!"
 785         .byte   13, 10, 0
 786
 787         # If we get here, all is good
 788 a20_done:
 789
 790 #endif /* CONFIG_X86_VOYAGER */
 791 # set up gdt and idt
 792         lidt    idt_48                          # load idt with 0,0
 793         xorl    %eax, %eax                      # Compute gdt_base
 794         movw    %ds, %ax                        # (Convert %ds:gdt to a linear ptr)
 795         shll    $4, %eax
 796         addl    $gdt, %eax
 797         movl    %eax, (gdt_48+2)
 798         lgdt    gdt_48                          # load gdt with whatever is
 799                                                 # appropriate
 800
 801 # make sure any possible coprocessor is properly reset..
 802         xorw    %ax, %ax
 803         outb    %al, $0xf0
 804         call    delay
 805
 806         outb    %al, $0xf1
 807         call    delay
 808
 809 # well, that went ok, I hope. Now we mask all interrupts - the rest
 810 # is done in init_IRQ().
 811         movb    $0xFF, %al                      # mask all interrupts for now
 812         outb    %al, $0xA1
 813         call    delay
 814
 815         movb    $0xFB, %al                      # mask all irq's but irq2 which
 816         outb    %al, $0x21                      # is cascaded
 817
 818 # Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
 819 # need no steenking BIOS anyway (except for the initial loading :-).
 820 # The BIOS-routine wants lots of unnecessary data, and it's less
 821 # "interesting" anyway. This is how REAL programmers do it.
 822 #
 823 # Well, now's the time to actually move into protected mode. To make
 824 # things as simple as possible, we do no register set-up or anything,
 825 # we let the gnu-compiled 32-bit programs do that. We just jump to
 826 # absolute address 0x1000 (or the loader supplied one),
 827 # in 32-bit protected mode.
 828 #
 829 # Note that the short jump isn't strictly needed, although there are
 830 # reasons why it might be a good idea. It won't hurt in any case.
 831         movw    $1, %ax                         # protected mode (PE) bit
 832         lmsw    %ax                             # This is it!
 833         jmp     flush_instr
 834
 835 flush_instr:
 836         xorw    %bx, %bx                        # Flag to indicate a boot
 837         xorl    %esi, %esi                      # Pointer to real-mode code
 838         movw    %cs, %si
 839         subw    $DELTA_INITSEG, %si
 840         shll    $4, %esi                        # Convert to 32-bit pointer
 841
 842 # jump to startup_32 in arch/i386/boot/compressed/head.S
 843 #
 844 # NOTE: For high loaded big kernels we need a
 845 #       jmpi    0x100000,__BOOT_CS
 846 #
 847 #       but we yet haven't reloaded the CS register, so the default size
 848 #       of the target offset still is 16 bit.
 849 #       However, using an operand prefix (0x66), the CPU will properly
 850 #       take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
 851 #       Manual, Mixing 16-bit and 32-bit code, page 16-6)
 852
 853         .byte 0x66, 0xea                        # prefix + jmpi-opcode
 854 code32: .long   0x1000                          # will be set to 0x100000
 855                                                 # for big kernels
 856         .word   __BOOT_CS
 857
 858 # Here's a bunch of information about your current kernel..
 859 kernel_version: .ascii  UTS_RELEASE
 860                 .ascii  " ("
 861                 .ascii  LINUX_COMPILE_BY
 862                 .ascii  "@"
 863                 .ascii  LINUX_COMPILE_HOST
 864                 .ascii  ") "
 865                 .ascii  UTS_VERSION
 866                 .byte   0
 867
 868 # This is the default real mode switch routine.
 869 # to be called just before protected mode transition
 870 default_switch:
 871         cli                                     # no interrupts allowed !
 872         movb    $0x80, %al                      # disable NMI for bootup
 873                                                 # sequence
 874         outb    %al, $0x70
 875         lret
 876
 877
 878 #ifndef CONFIG_X86_VOYAGER
 879 # This routine tests whether or not A20 is enabled.  If so, it
 880 # exits with zf = 0.
 881 #
 882 # The memory address used, 0x200, is the int $0x80 vector, which
 883 # should be safe.
 884
 885 A20_TEST_ADDR = 4*0x80
 886
 887 a20_test:
 888         pushw   %cx
 889         pushw   %ax
 890         xorw    %cx, %cx
 891         movw    %cx, %fs                        # Low memory
 892         decw    %cx
 893         movw    %cx, %gs                        # High memory area
 894         movw    $A20_TEST_LOOPS, %cx
 895         movw    %fs:(A20_TEST_ADDR), %ax
 896         pushw   %ax
 897 a20_test_wait:
 898         incw    %ax
 899         movw    %ax, %fs:(A20_TEST_ADDR)
 900         call    delay                           # Serialize and make delay constant
 901         cmpw    %gs:(A20_TEST_ADDR+0x10), %ax
 902         loope   a20_test_wait
 903
 904         popw    %fs:(A20_TEST_ADDR)
 905         popw    %ax
 906         popw    %cx
 907         ret
 908
 909 #endif /* CONFIG_X86_VOYAGER */
 910
 911 # This routine checks that the keyboard command queue is empty
 912 # (after emptying the output buffers)
 913 #
 914 # Some machines have delusions that the keyboard buffer is always full
 915 # with no keyboard attached...
 916 #
 917 # If there is no keyboard controller, we will usually get 0xff
 918 # to all the reads.  With each IO taking a microsecond and
 919 # a timeout of 100,000 iterations, this can take about half a
 920 # second ("delay" == outb to port 0x80). That should be ok,
 921 # and should also be plenty of time for a real keyboard controller
 922 # to empty.
 923 #
 924
 925 empty_8042:
 926         pushl   %ecx
 927         movl    $100000, %ecx
 928
 929 empty_8042_loop:
 930         decl    %ecx
 931         jz      empty_8042_end_loop
 932
 933         call    delay
 934
 935         inb     $0x64, %al                      # 8042 status port
 936         testb   $1, %al                         # output buffer?
 937         jz      no_output
 938
 939         call    delay
 940         inb     $0x60, %al                      # read it
 941         jmp     empty_8042_loop
 942
 943 no_output:
 944         testb   $2, %al                         # is input buffer full?
 945         jnz     empty_8042_loop                 # yes - loop
 946 empty_8042_end_loop:
 947         popl    %ecx
 948         ret
 949
 950 # Read the cmos clock. Return the seconds in al
 951 gettime:
 952         pushw   %cx
 953         movb    $0x02, %ah
 954         int     $0x1a
 955         movb    %dh, %al                        # %dh contains the seconds
 956         andb    $0x0f, %al
 957         movb    %dh, %ah
 958         movb    $0x04, %cl
 959         shrb    %cl, %ah
 960         aad
 961         popw    %cx
 962         ret
 963
 964 # Delay is needed after doing I/O
 965 delay:
 966         outb    %al,$0x80
 967         ret
 968
 969 # Descriptor tables
 970 #
 971 # NOTE: The intel manual says gdt should be sixteen bytes aligned for
 972 # efficiency reasons.  However, there are machines which are known not
 973 # to boot with misaligned GDTs, so alter this at your peril!  If you alter
 974 # GDT_ENTRY_BOOT_CS (in asm/segment.h) remember to leave at least two
 975 # empty GDT entries (one for NULL and one reserved).
 976 #
 977 # NOTE: On some CPUs, the GDT must be 8 byte aligned.  This is
 978 # true for the Voyager Quad CPU card which will not boot without
 979 # This directive.  16 byte aligment is recommended by intel.
 980 #
 981         .align 16
 982 gdt:
 983         .fill GDT_ENTRY_BOOT_CS,8,0
 984
 985         .word   0xFFFF                          # 4Gb - (0x100000*0x1000 = 4Gb)
 986         .word   0                               # base address = 0
 987         .word   0x9A00                          # code read/exec
 988         .word   0x00CF                          # granularity = 4096, 386
 989                                                 #  (+5th nibble of limit)
 990
 991         .word   0xFFFF                          # 4Gb - (0x100000*0x1000 = 4Gb)
 992         .word   0                               # base address = 0
 993         .word   0x9200                          # data read/write
 994         .word   0x00CF                          # granularity = 4096, 386
 995                                                 #  (+5th nibble of limit)
 996 gdt_end:
 997         .align  4
 998
 999         .word   0                               # alignment byte
1000 idt_48:
1001         .word   0                               # idt limit = 0
1002         .word   0, 0                            # idt base = 0L
1003
1004         .word   0                               # alignment byte
1005 gdt_48:
1006         .word   gdt_end - gdt - 1               # gdt limit
1007         .word   0, 0                            # gdt base (filled in later)
1008
1009 # Include video setup & detection code
1010
1011 #include "video.S"
1012
1013 # Setup signature -- must be last
1014 setup_sig1:     .word   SIG1
1015 setup_sig2:     .word   SIG2
1016
1017 # After this point, there is some free space which is used by the video mode
1018 # handling code to store the temporary mode table (not used by the kernel).
1019
1020 modelist:
1021
1022 .text
1023 endtext:
1024 .data
1025 enddata:
1026 .bss
1027 endbss: