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 * BIOS Enhanced Disk Drive support 49 * by Matt Domsch <Matt_Domsch@dell.com> October 2002 50 * conformant to T13 Committee www.t13.org 51 * projects 1572D, 1484D, 1386D, 1226DT 52 * disk signature read by Matt Domsch <Matt_Domsch@dell.com> 53 * and Andrew Wilks <Andrew_Wilks@dell.com> September 2003 54 */ 55 56#include <linux/config.h> 57#include <asm/segment.h> 58#include <linux/version.h> 59#include <linux/compile.h> 60#include <asm/boot.h> 61#include <asm/e820.h> 62#include <asm/edd.h> 63#include <asm/page.h> 64 65/* Signature words to ensure LILO loaded us right */ 66#define SIG1 0xAA55 67#define SIG2 0x5A5A 68 69INITSEG = DEF_INITSEG # 0x9000, we move boot here, out of the way 70SYSSEG = DEF_SYSSEG # 0x1000, system loaded at 0x10000 (65536). 71SETUPSEG = DEF_SETUPSEG # 0x9020, this is the current segment 72 # ... and the former contents of CS 73 74DELTA_INITSEG = SETUPSEG - INITSEG # 0x0020 75 76.code16 77.globl begtext, begdata, begbss, endtext, enddata, endbss 78 79.text 80begtext: 81.data 82begdata: 83.bss 84begbss: 85.text 86 87start: 88 jmp trampoline 89 90# This is the setup header, and it must start at %cs:2 (old 0x9020:2) 91 92 .ascii "HdrS" # header signature 93 .word 0x0203 # header version number (>= 0x0105) 94 # or else old loadlin-1.5 will fail) 95realmode_swtch: .word 0, 0 # default_switch, SETUPSEG 96start_sys_seg: .word SYSSEG 97 .word kernel_version # pointing to kernel version string 98 # above section of header is compatible 99 # with loadlin-1.5 (header v1.5). Don't 100 # change it. 101 102type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin, 103 # Bootlin, SYSLX, bootsect...) 104 # See Documentation/i386/boot.txt for 105 # assigned ids 106 107# flags, unused bits must be zero (RFU) bit within loadflags 108loadflags: 109LOADED_HIGH = 1 # If set, the kernel is loaded high 110CAN_USE_HEAP = 0x80 # If set, the loader also has set 111 # heap_end_ptr to tell how much 112 # space behind setup.S can be used for 113 # heap purposes. 114 # Only the loader knows what is free 115#ifndef __BIG_KERNEL__ 116 .byte 0 117#else 118 .byte LOADED_HIGH 119#endif 120 121setup_move_size: .word 0x8000 # size to move, when setup is not 122 # loaded at 0x90000. We will move setup 123 # to 0x90000 then just before jumping 124 # into the kernel. However, only the 125 # loader knows how much data behind 126 # us also needs to be loaded. 127 128code32_start: # here loaders can put a different 129 # start address for 32-bit code. 130#ifndef __BIG_KERNEL__ 131 .long 0x1000 # 0x1000 = default for zImage 132#else 133 .long 0x100000 # 0x100000 = default for big kernel 134#endif 135 136ramdisk_image: .long 0 # address of loaded ramdisk image 137 # Here the loader puts the 32-bit 138 # address where it loaded the image. 139 # This only will be read by the kernel. 140 141ramdisk_size: .long 0 # its size in bytes 142 143bootsect_kludge: 144 .word bootsect_helper, SETUPSEG 145 146heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later) 147 # space from here (exclusive) down to 148 # end of setup code can be used by setup 149 # for local heap purposes. 150 151pad1: .word 0 152cmd_line_ptr: .long 0 # (Header version 0x0202 or later) 153 # If nonzero, a 32-bit pointer 154 # to the kernel command line. 155 # The command line should be 156 # located between the start of 157 # setup and the end of low 158 # memory (0xa0000), or it may 159 # get overwritten before it 160 # gets read. If this field is 161 # used, there is no longer 162 # anything magical about the 163 # 0x90000 segment; the setup 164 # can be located anywhere in 165 # low memory 0x10000 or higher. 166 167ramdisk_max: .long __MAXMEM-1 # (Header version 0x0203 or later) 168 # The highest safe address for 169 # the contents of an initrd 170 171trampoline: call start_of_setup 172 .space 1024 173# End of setup header ##################################################### 174 175start_of_setup: 176# Bootlin depends on this being done early 177 movw $0x01500, %ax 178 movb $0x81, %dl 179 int $0x13 180 181#ifdef SAFE_RESET_DISK_CONTROLLER 182# Reset the disk controller. 183 movw $0x0000, %ax 184 movb $0x80, %dl 185 int $0x13 186#endif 187 188# Set %ds = %cs, we know that SETUPSEG = %cs at this point 189 movw %cs, %ax # aka SETUPSEG 190 movw %ax, %ds 191# Check signature at end of setup 192 cmpw $SIG1, setup_sig1 193 jne bad_sig 194 195 cmpw $SIG2, setup_sig2 196 jne bad_sig 197 198 jmp good_sig1 199 200# Routine to print asciiz string at ds:si 201prtstr: 202 lodsb 203 andb %al, %al 204 jz fin 205 206 call prtchr 207 jmp prtstr 208 209fin: ret 210 211# Space printing 212prtsp2: call prtspc # Print double space 213prtspc: movb $0x20, %al # Print single space (note: fall-thru) 214 215# Part of above routine, this one just prints ascii al 216prtchr: pushw %ax 217 pushw %cx 218 xorb %bh, %bh 219 movw $0x01, %cx 220 movb $0x0e, %ah 221 int $0x10 222 popw %cx 223 popw %ax 224 ret 225 226beep: movb $0x07, %al 227 jmp prtchr 228 229no_sig_mess: .string "No setup signature found ..." 230 231good_sig1: 232 jmp good_sig 233 234# We now have to find the rest of the setup code/data 235bad_sig: 236 movw %cs, %ax # SETUPSEG 237 subw $DELTA_INITSEG, %ax # INITSEG 238 movw %ax, %ds 239 xorb %bh, %bh 240 movb (497), %bl # get setup sect from bootsect 241 subw $4, %bx # LILO loads 4 sectors of setup 242 shlw $8, %bx # convert to words (1sect=2^8 words) 243 movw %bx, %cx 244 shrw $3, %bx # convert to segment 245 addw $SYSSEG, %bx 246 movw %bx, %cs:start_sys_seg 247# Move rest of setup code/data to here 248 movw $2048, %di # four sectors loaded by LILO 249 subw %si, %si 250 pushw %cs 251 popw %es 252 movw $SYSSEG, %ax 253 movw %ax, %ds 254 rep 255 movsw 256 movw %cs, %ax # aka SETUPSEG 257 movw %ax, %ds 258 cmpw $SIG1, setup_sig1 259 jne no_sig 260 261 cmpw $SIG2, setup_sig2 262 jne no_sig 263 264 jmp good_sig 265 266no_sig: 267 lea no_sig_mess, %si 268 call prtstr 269 270no_sig_loop: 271 hlt 272 jmp no_sig_loop 273 274good_sig: 275 movw %cs, %ax # aka SETUPSEG 276 subw $DELTA_INITSEG, %ax # aka INITSEG 277 movw %ax, %ds 278# Check if an old loader tries to load a big-kernel 279 testb $LOADED_HIGH, %cs:loadflags # Do we have a big kernel? 280 jz loader_ok # No, no danger for old loaders. 281 282 cmpb $0, %cs:type_of_loader # Do we have a loader that 283 # can deal with us? 284 jnz loader_ok # Yes, continue. 285 286 pushw %cs # No, we have an old loader, 287 popw %ds # die. 288 lea loader_panic_mess, %si 289 call prtstr 290 291 jmp no_sig_loop 292 293loader_panic_mess: .string "Wrong loader, giving up..." 294 295loader_ok: 296# Get memory size (extended mem, kB) 297 298 xorl %eax, %eax 299 movl %eax, (0x1e0) 300#ifndef STANDARD_MEMORY_BIOS_CALL 301 movb %al, (E820NR) 302# Try three different memory detection schemes. First, try 303# e820h, which lets us assemble a memory map, then try e801h, 304# which returns a 32-bit memory size, and finally 88h, which 305# returns 0-64m 306 307# method E820H: 308# the memory map from hell. e820h returns memory classified into 309# a whole bunch of different types, and allows memory holes and 310# everything. We scan through this memory map and build a list 311# of the first 32 memory areas, which we return at [E820MAP]. 312# This is documented at http://www.teleport.com/~acpi/acpihtml/topic245.htm 313 314#define SMAP 0x534d4150 315 316meme820: 317 xorl %ebx, %ebx # continuation counter 318 movw $E820MAP, %di # point into the whitelist 319 # so we can have the bios 320 # directly write into it. 321 322jmpe820: 323 movl $0x0000e820, %eax # e820, upper word zeroed 324 movl $SMAP, %edx # ascii 'SMAP' 325 movl $20, %ecx # size of the e820rec 326 pushw %ds # data record. 327 popw %es 328 int $0x15 # make the call 329 jc bail820 # fall to e801 if it fails 330 331 cmpl $SMAP, %eax # check the return is `SMAP' 332 jne bail820 # fall to e801 if it fails 333 334# cmpl $1, 16(%di) # is this usable memory? 335# jne again820 336 337 # If this is usable memory, we save it by simply advancing %di by 338 # sizeof(e820rec). 339 # 340good820: 341 movb (E820NR), %al # up to 32 entries 342 cmpb $E820MAX, %al 343 jnl bail820 344 345 incb (E820NR) 346 movw %di, %ax 347 addw $20, %ax 348 movw %ax, %di 349again820: 350 cmpl $0, %ebx # check to see if 351 jne jmpe820 # %ebx is set to EOF 352bail820: 353 354 355# method E801H: 356# memory size is in 1k chunksizes, to avoid confusing loadlin. 357# we store the 0xe801 memory size in a completely different place, 358# because it will most likely be longer than 16 bits. 359# (use 1e0 because that's what Larry Augustine uses in his 360# alternative new memory detection scheme, and it's sensible 361# to write everything into the same place.) 362 363meme801: 364 stc # fix to work around buggy 365 xorw %cx,%cx # BIOSes which dont clear/set 366 xorw %dx,%dx # carry on pass/error of 367 # e801h memory size call 368 # or merely pass cx,dx though 369 # without changing them. 370 movw $0xe801, %ax 371 int $0x15 372 jc mem88 373 374 cmpw $0x0, %cx # Kludge to handle BIOSes 375 jne e801usecxdx # which report their extended 376 cmpw $0x0, %dx # memory in AX/BX rather than 377 jne e801usecxdx # CX/DX. The spec I have read 378 movw %ax, %cx # seems to indicate AX/BX 379 movw %bx, %dx # are more reasonable anyway... 380 381e801usecxdx: 382 andl $0xffff, %edx # clear sign extend 383 shll $6, %edx # and go from 64k to 1k chunks 384 movl %edx, (0x1e0) # store extended memory size 385 andl $0xffff, %ecx # clear sign extend 386 addl %ecx, (0x1e0) # and add lower memory into 387 # total size. 388 389# Ye Olde Traditional Methode. Returns the memory size (up to 16mb or 390# 64mb, depending on the bios) in ax. 391mem88: 392 393#endif 394 movb $0x88, %ah 395 int $0x15 396 movw %ax, (2) 397 398# Set the keyboard repeat rate to the max 399 movw $0x0305, %ax 400 xorw %bx, %bx 401 int $0x16 402 403# Check for video adapter and its parameters and allow the 404# user to browse video modes. 405 call video # NOTE: we need %ds pointing 406 # to bootsector 407 408# Get hd0 data... 409 xorw %ax, %ax 410 movw %ax, %ds 411 ldsw (4 * 0x41), %si 412 movw %cs, %ax # aka SETUPSEG 413 subw $DELTA_INITSEG, %ax # aka INITSEG 414 pushw %ax 415 movw %ax, %es 416 movw $0x0080, %di 417 movw $0x10, %cx 418 pushw %cx 419 cld 420 rep 421 movsb 422# Get hd1 data... 423 xorw %ax, %ax 424 movw %ax, %ds 425 ldsw (4 * 0x46), %si 426 popw %cx 427 popw %es 428 movw $0x0090, %di 429 rep 430 movsb 431# Check that there IS a hd1 :-) 432 movw $0x01500, %ax 433 movb $0x81, %dl 434 int $0x13 435 jc no_disk1 436 437 cmpb $3, %ah 438 je is_disk1 439 440no_disk1: 441 movw %cs, %ax # aka SETUPSEG 442 subw $DELTA_INITSEG, %ax # aka INITSEG 443 movw %ax, %es 444 movw $0x0090, %di 445 movw $0x10, %cx 446 xorw %ax, %ax 447 cld 448 rep 449 stosb 450is_disk1: 451# check for Micro Channel (MCA) bus 452 movw %cs, %ax # aka SETUPSEG 453 subw $DELTA_INITSEG, %ax # aka INITSEG 454 movw %ax, %ds 455 xorw %ax, %ax 456 movw %ax, (0xa0) # set table length to 0 457 movb $0xc0, %ah 458 stc 459 int $0x15 # moves feature table to es:bx 460 jc no_mca 461 462 pushw %ds 463 movw %es, %ax 464 movw %ax, %ds 465 movw %cs, %ax # aka SETUPSEG 466 subw $DELTA_INITSEG, %ax # aka INITSEG 467 movw %ax, %es 468 movw %bx, %si 469 movw $0xa0, %di 470 movw (%si), %cx 471 addw $2, %cx # table length is a short 472 cmpw $0x10, %cx 473 jc sysdesc_ok 474 475 movw $0x10, %cx # we keep only first 16 bytes 476sysdesc_ok: 477 rep 478 movsb 479 popw %ds 480no_mca: 481# Check for PS/2 pointing device 482 movw %cs, %ax # aka SETUPSEG 483 subw $DELTA_INITSEG, %ax # aka INITSEG 484 movw %ax, %ds 485 movw $0, (0x1ff) # default is no pointing device 486 int $0x11 # int 0x11: equipment list 487 testb $0x04, %al # check if mouse installed 488 jz no_psmouse 489 490 movw $0xAA, (0x1ff) # device present 491no_psmouse: 492 493#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE) 494# Then check for an APM BIOS... 495 # %ds points to the bootsector 496 movw $0, 0x40 # version = 0 means no APM BIOS 497 movw $0x05300, %ax # APM BIOS installation check 498 xorw %bx, %bx 499 int $0x15 500 jc done_apm_bios # Nope, no APM BIOS 501 502 cmpw $0x0504d, %bx # Check for "PM" signature 503 jne done_apm_bios # No signature, no APM BIOS 504 505 andw $0x02, %cx # Is 32 bit supported? 506 je done_apm_bios # No 32-bit, no (good) APM BIOS 507 508 movw $0x05304, %ax # Disconnect first just in case 509 xorw %bx, %bx 510 int $0x15 # ignore return code 511 movw $0x05303, %ax # 32 bit connect 512 xorl %ebx, %ebx 513 xorw %cx, %cx # paranoia :-) 514 xorw %dx, %dx # ... 515 xorl %esi, %esi # ... 516 xorw %di, %di # ... 517 int $0x15 518 jc no_32_apm_bios # Ack, error. 519 520 movw %ax, (66) # BIOS code segment 521 movl %ebx, (68) # BIOS entry point offset 522 movw %cx, (72) # BIOS 16 bit code segment 523 movw %dx, (74) # BIOS data segment 524 movl %esi, (78) # BIOS code segment lengths 525 movw %di, (82) # BIOS data segment length 526# Redo the installation check as the 32 bit connect 527# modifies the flags returned on some BIOSs 528 movw $0x05300, %ax # APM BIOS installation check 529 xorw %bx, %bx 530 xorw %cx, %cx # paranoia 531 int $0x15 532 jc apm_disconnect # error -> shouldn't happen 533 534 cmpw $0x0504d, %bx # check for "PM" signature 535 jne apm_disconnect # no sig -> shouldn't happen 536 537 movw %ax, (64) # record the APM BIOS version 538 movw %cx, (76) # and flags 539 jmp done_apm_bios 540 541apm_disconnect: # Tidy up 542 movw $0x05304, %ax # Disconnect 543 xorw %bx, %bx 544 int $0x15 # ignore return code 545 546 jmp done_apm_bios 547 548no_32_apm_bios: 549 andw $0xfffd, (76) # remove 32 bit support bit 550done_apm_bios: 551#endif 552 553#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) 554# Read the first sector of device 80h and store the 4-byte signature 555 movl $0xFFFFFFFF, %eax 556 movl %eax, (DISK80_SIG_BUFFER) # assume failure 557 movb $READ_SECTORS, %ah 558 movb $1, %al # read 1 sector 559 movb $0x80, %dl # from device 80 560 movb $0, %dh # at head 0 561 movw $1, %cx # cylinder 0, sector 0 562 pushw %es 563 pushw %ds 564 popw %es 565 movw $EDDBUF, %bx 566 int $0x13 567 jc disk_sig_done 568 movl (EDDBUF+MBR_SIG_OFFSET), %eax 569 movl %eax, (DISK80_SIG_BUFFER) # store success 570disk_sig_done: 571 popw %es 572 573# Do the BIOS Enhanced Disk Drive calls 574# This consists of two calls: 575# int 13h ah=41h "Check Extensions Present" 576# int 13h ah=48h "Get Device Parameters" 577# 578# A buffer of size EDDMAXNR*(EDDEXTSIZE+EDDPARMSIZE) is reserved for our use 579# in the empty_zero_page at EDDBUF. The first four bytes of which are 580# used to store the device number, interface support map and version 581# results from fn41. The following 74 bytes are used to store 582# the results from fn48. Starting from device 80h, fn41, then fn48 583# are called and their results stored in EDDBUF+n*(EDDEXTSIZE+EDDPARMIZE). 584# Then the pointer is incremented to store the data for the next call. 585# This repeats until either a device doesn't exist, or until EDDMAXNR 586# devices have been stored. 587# The one tricky part is that ds:si always points four bytes into 588# the structure, and the fn41 results are stored at offsets 589# from there. This removes the need to increment the pointer for 590# every store, and leaves it ready for the fn48 call. 591# A second one-byte buffer, EDDNR, in the empty_zero_page stores 592# the number of BIOS devices which exist, up to EDDMAXNR. 593# In setup.c, copy_edd() stores both empty_zero_page buffers away 594# for later use, as they would get overwritten otherwise. 595# This code is sensitive to the size of the structs in edd.h 596edd_start: 597 # %ds points to the bootsector 598 # result buffer for fn48 599 movw $EDDBUF+EDDEXTSIZE, %si # in ds:si, fn41 results 600 # kept just before that 601 movb $0, (EDDNR) # zero value at EDDNR 602 movb $0x80, %dl # BIOS device 0x80 603 604edd_check_ext: 605 movb $CHECKEXTENSIONSPRESENT, %ah # Function 41 606 movw $EDDMAGIC1, %bx # magic 607 int $0x13 # make the call 608 jc edd_done # no more BIOS devices 609 610 cmpw $EDDMAGIC2, %bx # is magic right? 611 jne edd_next # nope, next... 612 613 movb %dl, %ds:-4(%si) # store device number 614 movb %ah, %ds:-3(%si) # store version 615 movw %cx, %ds:-2(%si) # store extensions 616 incb (EDDNR) # note that we stored something 617 618edd_get_device_params: 619 movw $EDDPARMSIZE, %ds:(%si) # put size 620 movb $GETDEVICEPARAMETERS, %ah # Function 48 621 int $0x13 # make the call 622 # Don't check for fail return 623 # it doesn't matter. 624 movw %si, %ax # increment si 625 addw $EDDPARMSIZE+EDDEXTSIZE, %ax 626 movw %ax, %si 627 628edd_next: 629 incb %dl # increment to next device 630 cmpb $EDDMAXNR, (EDDNR) # Out of space? 631 jb edd_check_ext # keep looping 632 633edd_done: 634#endif 635 636# Now we want to move to protected mode ... 637 cmpw $0, %cs:realmode_swtch 638 jz rmodeswtch_normal 639 640 lcall %cs:realmode_swtch 641 642 jmp rmodeswtch_end 643 644rmodeswtch_normal: 645 pushw %cs 646 call default_switch 647 648rmodeswtch_end: 649# we get the code32 start address and modify the below 'jmpi' 650# (loader may have changed it) 651 movl %cs:code32_start, %eax 652 movl %eax, %cs:code32 653 654# Now we move the system to its rightful place ... but we check if we have a 655# big-kernel. In that case we *must* not move it ... 656 testb $LOADED_HIGH, %cs:loadflags 657 jz do_move0 # .. then we have a normal low 658 # loaded zImage 659 # .. or else we have a high 660 # loaded bzImage 661 jmp end_move # ... and we skip moving 662 663do_move0: 664 movw $0x100, %ax # start of destination segment 665 movw %cs, %bp # aka SETUPSEG 666 subw $DELTA_INITSEG, %bp # aka INITSEG 667 movw %cs:start_sys_seg, %bx # start of source segment 668 cld 669do_move: 670 movw %ax, %es # destination segment 671 incb %ah # instead of add ax,#0x100 672 movw %bx, %ds # source segment 673 addw $0x100, %bx 674 subw %di, %di 675 subw %si, %si 676 movw $0x800, %cx 677 rep 678 movsw 679 cmpw %bp, %bx # assume start_sys_seg > 0x200, 680 # so we will perhaps read one 681 # page more than needed, but 682 # never overwrite INITSEG 683 # because destination is a 684 # minimum one page below source 685 jb do_move 686 687end_move: 688# then we load the segment descriptors 689 movw %cs, %ax # aka SETUPSEG 690 movw %ax, %ds 691 692# Check whether we need to be downward compatible with version <=201 693 cmpl $0, cmd_line_ptr 694 jne end_move_self # loader uses version >=202 features 695 cmpb $0x20, type_of_loader 696 je end_move_self # bootsect loader, we know of it 697 698# Boot loader doesnt support boot protocol version 2.02. 699# If we have our code not at 0x90000, we need to move it there now. 700# We also then need to move the params behind it (commandline) 701# Because we would overwrite the code on the current IP, we move 702# it in two steps, jumping high after the first one. 703 movw %cs, %ax 704 cmpw $SETUPSEG, %ax 705 je end_move_self 706 707 cli # make sure we really have 708 # interrupts disabled ! 709 # because after this the stack 710 # should not be used 711 subw $DELTA_INITSEG, %ax # aka INITSEG 712 movw %ss, %dx 713 cmpw %ax, %dx 714 jb move_self_1 715 716 addw $INITSEG, %dx 717 subw %ax, %dx # this will go into %ss after 718 # the move 719move_self_1: 720 movw %ax, %ds 721 movw $INITSEG, %ax # real INITSEG 722 movw %ax, %es 723 movw %cs:setup_move_size, %cx 724 std # we have to move up, so we use 725 # direction down because the 726 # areas may overlap 727 movw %cx, %di 728 decw %di 729 movw %di, %si 730 subw $move_self_here+0x200, %cx 731 rep 732 movsb 733 ljmp $SETUPSEG, $move_self_here 734 735move_self_here: 736 movw $move_self_here+0x200, %cx 737 rep 738 movsb 739 movw $SETUPSEG, %ax 740 movw %ax, %ds 741 movw %dx, %ss 742end_move_self: # now we are at the right place 743 744# 745# Enable A20. This is at the very best an annoying procedure. 746# A20 code ported from SYSLINUX 1.52-1.63 by H. Peter Anvin. 747# AMD Elan bug fix by Robert Schwebel. 748# 749 750#if defined(CONFIG_MELAN) 751 movb $0x02, %al # alternate A20 gate 752 outb %al, $0x92 # this works on SC410/SC520 753a20_elan_wait: 754 call a20_test 755 jz a20_elan_wait 756 jmp a20_done 757#endif 758 759 760A20_TEST_LOOPS = 32 # Iterations per wait 761A20_ENABLE_LOOPS = 255 # Total loops to try 762 763 764a20_try_loop: 765 766 # First, see if we are on a system with no A20 gate. 767a20_none: 768 call a20_test 769 jnz a20_done 770 771 # Next, try the BIOS (INT 0x15, AX=0x2401) 772a20_bios: 773 movw $0x2401, %ax 774 pushfl # Be paranoid about flags 775 int $0x15 776 popfl 777 778 call a20_test 779 jnz a20_done 780 781 # Try enabling A20 through the keyboard controller 782a20_kbc: 783 call empty_8042 784 785 call a20_test # Just in case the BIOS worked 786 jnz a20_done # but had a delayed reaction. 787 788 movb $0xD1, %al # command write 789 outb %al, $0x64 790 call empty_8042 791 792 movb $0xDF, %al # A20 on 793 outb %al, $0x60 794 call empty_8042 795 796 # Wait until a20 really *is* enabled; it can take a fair amount of 797 # time on certain systems; Toshiba Tecras are known to have this 798 # problem. 799a20_kbc_wait: 800 xorw %cx, %cx 801a20_kbc_wait_loop: 802 call a20_test 803 jnz a20_done 804 loop a20_kbc_wait_loop 805 806 # Final attempt: use "configuration port A" 807a20_fast: 808 inb $0x92, %al # Configuration Port A 809 orb $0x02, %al # "fast A20" version 810 andb $0xFE, %al # don't accidentally reset 811 outb %al, $0x92 812 813 # Wait for configuration port A to take effect 814a20_fast_wait: 815 xorw %cx, %cx 816a20_fast_wait_loop: 817 call a20_test 818 jnz a20_done 819 loop a20_fast_wait_loop 820 821 # A20 is still not responding. Try frobbing it again. 822 # 823 decb (a20_tries) 824 jnz a20_try_loop 825 826 movw $a20_err_msg, %si 827 call prtstr 828 829a20_die: 830 hlt 831 jmp a20_die 832 833a20_tries: 834 .byte A20_ENABLE_LOOPS 835 836a20_err_msg: 837 .ascii "linux: fatal error: A20 gate not responding!" 838 .byte 13, 10, 0 839 840 # If we get here, all is good 841a20_done: 842 843# set up gdt and idt 844 lidt idt_48 # load idt with 0,0 845 xorl %eax, %eax # Compute gdt_base 846 movw %ds, %ax # (Convert %ds:gdt to a linear ptr) 847 shll $4, %eax 848 addl $gdt, %eax 849 movl %eax, (gdt_48+2) 850 lgdt gdt_48 # load gdt with whatever is 851 # appropriate 852 853# make sure any possible coprocessor is properly reset.. 854 xorw %ax, %ax 855 outb %al, $0xf0 856 call delay 857 858 outb %al, $0xf1 859 call delay 860 861# well, that went ok, I hope. Now we mask all interrupts - the rest 862# is done in init_IRQ(). 863 movb $0xFF, %al # mask all interrupts for now 864 outb %al, $0xA1 865 call delay 866 867 movb $0xFB, %al # mask all irq's but irq2 which 868 outb %al, $0x21 # is cascaded 869 870# Well, that certainly wasn't fun :-(. Hopefully it works, and we don't 871# need no steenking BIOS anyway (except for the initial loading :-). 872# The BIOS-routine wants lots of unnecessary data, and it's less 873# "interesting" anyway. This is how REAL programmers do it. 874# 875# Well, now's the time to actually move into protected mode. To make 876# things as simple as possible, we do no register set-up or anything, 877# we let the gnu-compiled 32-bit programs do that. We just jump to 878# absolute address 0x1000 (or the loader supplied one), 879# in 32-bit protected mode. 880# 881# Note that the short jump isn't strictly needed, although there are 882# reasons why it might be a good idea. It won't hurt in any case. 883 movw $1, %ax # protected mode (PE) bit 884 lmsw %ax # This is it! 885 jmp flush_instr 886 887flush_instr: 888 xorw %bx, %bx # Flag to indicate a boot 889 xorl %esi, %esi # Pointer to real-mode code 890 movw %cs, %si 891 subw $DELTA_INITSEG, %si 892 shll $4, %esi # Convert to 32-bit pointer 893# NOTE: For high loaded big kernels we need a 894# jmpi 0x100000,__KERNEL_CS 895# 896# but we yet haven't reloaded the CS register, so the default size 897# of the target offset still is 16 bit. 898# However, using an operand prefix (0x66), the CPU will properly 899# take our 48 bit far pointer. (INTeL 80386 Programmer's Reference 900# Manual, Mixing 16-bit and 32-bit code, page 16-6) 901 902 .byte 0x66, 0xea # prefix + jmpi-opcode 903code32: .long 0x1000 # will be set to 0x100000 904 # for big kernels 905 .word __KERNEL_CS 906 907# Here's a bunch of information about your current kernel.. 908kernel_version: .ascii UTS_RELEASE 909 .ascii " (" 910 .ascii LINUX_COMPILE_BY 911 .ascii "@" 912 .ascii LINUX_COMPILE_HOST 913 .ascii ") " 914 .ascii UTS_VERSION 915 .byte 0 916 917# This is the default real mode switch routine. 918# to be called just before protected mode transition 919default_switch: 920 cli # no interrupts allowed ! 921 movb $0x80, %al # disable NMI for bootup 922 # sequence 923 outb %al, $0x70 924 lret 925 926# This routine only gets called, if we get loaded by the simple 927# bootsect loader _and_ have a bzImage to load. 928# Because there is no place left in the 512 bytes of the boot sector, 929# we must emigrate to code space here. 930bootsect_helper: 931 cmpw $0, %cs:bootsect_es 932 jnz bootsect_second 933 934 movb $0x20, %cs:type_of_loader 935 movw %es, %ax 936 shrw $4, %ax 937 movb %ah, %cs:bootsect_src_base+2 938 movw %es, %ax 939 movw %ax, %cs:bootsect_es 940 subw $SYSSEG, %ax 941 lret # nothing else to do for now 942 943bootsect_second: 944 pushw %cx 945 pushw %si 946 pushw %bx 947 testw %bx, %bx # 64K full? 948 jne bootsect_ex 949 950 movw $0x8000, %cx # full 64K, INT15 moves words 951 pushw %cs 952 popw %es 953 movw $bootsect_gdt, %si 954 movw $0x8700, %ax 955 int $0x15 956 jc bootsect_panic # this, if INT15 fails 957 958 movw %cs:bootsect_es, %es # we reset %es to always point 959 incb %cs:bootsect_dst_base+2 # to 0x10000 960bootsect_ex: 961 movb %cs:bootsect_dst_base+2, %ah 962 shlb $4, %ah # we now have the number of 963 # moved frames in %ax 964 xorb %al, %al 965 popw %bx 966 popw %si 967 popw %cx 968 lret 969 970bootsect_gdt: 971 .word 0, 0, 0, 0 972 .word 0, 0, 0, 0 973 974bootsect_src: 975 .word 0xffff 976 977bootsect_src_base: 978 .byte 0x00, 0x00, 0x01 # base = 0x010000 979 .byte 0x93 # typbyte 980 .word 0 # limit16,base24 =0 981 982bootsect_dst: 983 .word 0xffff 984 985bootsect_dst_base: 986 .byte 0x00, 0x00, 0x10 # base = 0x100000 987 .byte 0x93 # typbyte 988 .word 0 # limit16,base24 =0 989 .word 0, 0, 0, 0 # BIOS CS 990 .word 0, 0, 0, 0 # BIOS DS 991 992bootsect_es: 993 .word 0 994 995bootsect_panic: 996 pushw %cs 997 popw %ds 998 cld 999 leaw bootsect_panic_mess, %si 1000 call prtstr 1001 1002bootsect_panic_loop: 1003 jmp bootsect_panic_loop 1004 1005bootsect_panic_mess: 1006 .string "INT15 refuses to access high mem, giving up." 1007 1008 1009# This routine tests whether or not A20 is enabled. If so, it 1010# exits with zf = 0. 1011# 1012# The memory address used, 0x200, is the int $0x80 vector, which 1013# should be safe. 1014 1015A20_TEST_ADDR = 4*0x80 1016 1017a20_test: 1018 pushw %cx 1019 pushw %ax 1020 xorw %cx, %cx 1021 movw %cx, %fs # Low memory 1022 decw %cx 1023 movw %cx, %gs # High memory area 1024 movw $A20_TEST_LOOPS, %cx 1025 movw %fs:(A20_TEST_ADDR), %ax 1026 pushw %ax 1027a20_test_wait: 1028 incw %ax 1029 movw %ax, %fs:(A20_TEST_ADDR) 1030 call delay # Serialize and make delay constant 1031 cmpw %gs:(A20_TEST_ADDR+0x10), %ax 1032 loope a20_test_wait 1033 1034 popw %fs:(A20_TEST_ADDR) 1035 popw %ax 1036 popw %cx 1037 ret 1038 1039# This routine checks that the keyboard command queue is empty 1040# (after emptying the output buffers) 1041# 1042# Some machines have delusions that the keyboard buffer is always full 1043# with no keyboard attached... 1044# 1045# If there is no keyboard controller, we will usually get 0xff 1046# to all the reads. With each IO taking a microsecond and 1047# a timeout of 100,000 iterations, this can take about half a 1048# second ("delay" == outb to port 0x80). That should be ok, 1049# and should also be plenty of time for a real keyboard controller 1050# to empty. 1051# 1052 1053empty_8042: 1054 pushl %ecx 1055 movl $100000, %ecx 1056 1057empty_8042_loop: 1058 decl %ecx 1059 jz empty_8042_end_loop 1060 1061 call delay 1062 1063 inb $0x64, %al # 8042 status port 1064 testb $1, %al # output buffer? 1065 jz no_output 1066 1067 call delay 1068 inb $0x60, %al # read it 1069 jmp empty_8042_loop 1070 1071no_output: 1072 testb $2, %al # is input buffer full? 1073 jnz empty_8042_loop # yes - loop 1074empty_8042_end_loop: 1075 popl %ecx 1076 ret 1077 1078# Read the cmos clock. Return the seconds in al 1079gettime: 1080 pushw %cx 1081 movb $0x02, %ah 1082 int $0x1a 1083 movb %dh, %al # %dh contains the seconds 1084 andb $0x0f, %al 1085 movb %dh, %ah 1086 movb $0x04, %cl 1087 shrb %cl, %ah 1088 aad 1089 popw %cx 1090 ret 1091 1092# Delay is needed after doing I/O 1093delay: 1094 outb %al,$0x80 1095 ret 1096 1097# Descriptor tables 1098gdt: 1099 .word 0, 0, 0, 0 # dummy 1100 .word 0, 0, 0, 0 # unused 1101 1102 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) 1103 .word 0 # base address = 0 1104 .word 0x9A00 # code read/exec 1105 .word 0x00CF # granularity = 4096, 386 1106 # (+5th nibble of limit) 1107 1108 .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) 1109 .word 0 # base address = 0 1110 .word 0x9200 # data read/write 1111 .word 0x00CF # granularity = 4096, 386 1112 # (+5th nibble of limit) 1113idt_48: 1114 .word 0 # idt limit = 0 1115 .word 0, 0 # idt base = 0L 1116gdt_48: 1117 .word 0x8000 # gdt limit=2048, 1118 # 256 GDT entries 1119 1120 .word 0, 0 # gdt base (filled in later) 1121 1122# Include video setup & detection code 1123 1124#include "video.S" 1125 1126# Setup signature -- must be last 1127setup_sig1: .word SIG1 1128setup_sig2: .word SIG2 1129 1130# After this point, there is some free space which is used by the video mode 1131# handling code to store the temporary mode table (not used by the kernel). 1132 1133modelist: 1134 1135.text 1136endtext: 1137.data 1138enddata: 1139.bss 1140endbss: 1141