DuetPkg/BootSector/start16.S

   1 #------------------------------------------------------------------------------
   2 #*
   3 #*   Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
   4 #*   This program and the accompanying materials
   5 #*   are licensed and made available under the terms and conditions of the BSD License
   6 #*   which accompanies this distribution.  The full text of the license may be found at
   7 #*   http://opensource.org/licenses/bsd-license.php
   8 #*
   9 #*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 #*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 #*
  12 #*    start16.asm
  13 #*
  14 #*   Abstract:
  15 #*
  16 #------------------------------------------------------------------------------
  17
  18         #.MODEL small
  19         .stack:
  20         .486p:
  21         .code:
  22
  23 .equ                        FAT_DIRECTORY_ENTRY_SIZE,   0x0020
  24 .equ                        FAT_DIRECTORY_ENTRY_SHIFT,  5
  25 .equ                        BLOCK_SIZE,                 0x0200
  26 .equ                        BLOCK_MASK,                 0x01ff
  27 .equ                        BLOCK_SHIFT,                9
  28
  29         .org 0x00
  30
  31 .global _start
  32 _start:
  33
  34 Ia32Jump:
  35   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  36   nop
  37
  38 OemId:             .ascii  "INTEL   "    # OemId               - 8 bytes
  39
  40 SectorSize:        .word  0              # Sector Size         - 16 bits
  41 SectorsPerCluster: .byte  0              # Sector Per Cluster  - 8 bits
  42 ReservedSectors:   .word  0              # Reserved Sectors    - 16 bits
  43 NoFats:            .byte  0              # Number of FATs      - 8 bits
  44 RootEntries:       .word  0              # Root Entries        - 16 bits
  45 Sectors:           .word  0              # Number of Sectors   - 16 bits
  46 Media:             .byte  0              # Media               - 8 bits  - ignored
  47 SectorsPerFat:     .word  0              # Sectors Per FAT     - 16 bits
  48 SectorsPerTrack:   .word  0              # Sectors Per Track   - 16 bits - ignored
  49 Heads:             .word  0              # Heads               - 16 bits - ignored
  50 HiddenSectors:     .long  0              # Hidden Sectors      - 32 bits - ignored
  51 LargeSectors:      .long  0              # Large Sectors       - 32 bits
  52 PhysicalDrive:     .byte  0              # PhysicalDriveNumber - 8 bits  - ignored
  53 CurrentHead:       .byte  0              # Current Head        - 8 bits
  54 Signature:         .byte  0              # Signature           - 8 bits  - ignored
  55 VolId:             .ascii  "    "        # Volume Serial Number- 4 bytes
  56 FatLabel:          .ascii  "           " # Label               - 11 bytes
  57 SystemId:          .ascii  "FAT16   "    # SystemId            - 8 bytes
  58
  59 BootSectorEntryPoint:
  60         #ASSUME ds:@code
  61         #ASSUME ss:@code
  62       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  63       # cx = Start Cluster of EfiLdr
  64       # dx = Start Cluster of Efivar.bin
  65
  66 # Re use the BPB data stored in Boot Sector
  67         movw    $0x7c00, %bp
  68
  69         pushw   %cx
  70 # Read Efivar.bin
  71 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  72         movw    $0x1900, %ax
  73         movw    %ax, %es
  74         testw   %dx, %dx
  75         jnz     CheckVarStoreSize
  76
  77         movb    $1, %al
  78 NoVarStore:
  79         pushw   %es
  80 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  81         movb    %al, %es:4
  82         jmp     SaveVolumeId
  83
  84 CheckVarStoreSize:
  85         movw    %dx, %di
  86         cmpl    $0x4000, %ds:2(%di)
  87         movb    $2, %al
  88         jne     NoVarStore
  89
  90 LoadVarStore:
  91         movb    $0, %al
  92         movb    %al, %es:4
  93         movw    (%di), %cx
  94 #       ES:DI = 1500:0
  95         xorw    %di, %di
  96         pushw   %es
  97         movw    $0x1500, %ax
  98         movw    %ax, %es
  99         call    ReadFile
 100 SaveVolumeId:
 101         popw    %es
 102         movw    VolId(%bp), %ax
 103         movw    %ax, %es:0                      # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 104         movw    VolId+2(%bp), %ax
 105         movw    %ax, %es:2
 106
 107 # Read Efildr
 108         popw    %cx
 109 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 110 #       ES:DI = 2000:0, first cluster will be read again
 111         xorw    %di, %di                            # di = 0
 112         movw    $0x2000, %ax
 113         movw    %ax, %es
 114         call    ReadFile
 115         movw    %cs, %ax
 116         movw    %ax, %cs:JumpSegment
 117
 118 JumpFarInstruction:
 119         .byte   0xea
 120 JumpOffset:
 121         .word   0x200
 122 JumpSegment:
 123         .word   0x2000
 124
 125
 126
 127 # ****************************************************************************
 128 # ReadFile
 129 #
 130 # Arguments:
 131 #   CX    = Start Cluster of File
 132 #   ES:DI = Buffer to store file content read from disk
 133 #
 134 # Return:
 135 #   (ES << 4 + DI) = end of file content Buffer
 136 #
 137 # ****************************************************************************
 138 ReadFile:
 139 # si      = NumberOfClusters
 140 # cx      = ClusterNumber
 141 # dx      = CachedFatSectorNumber
 142 # ds:0000 = CacheFatSectorBuffer
 143 # es:di   = Buffer to load file
 144 # bx      = NextClusterNumber
 145         pusha
 146         movw    $1, %si                             # NumberOfClusters = 1
 147         pushw   %cx                                 # Push Start Cluster onto stack
 148         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 149 FatChainLoop:
 150         movw    %cx, %ax                            # ax = ClusterNumber
 151         andw    $0xfff8, %ax                        # ax = ax & 0xfff8
 152         cmpw    $0xfff8, %ax                        # See if this is the last cluster
 153         je      FoundLastCluster                    # Jump if last cluster found
 154         movw    %cx, %ax                            # ax = ClusterNumber
 155         shlw    %ax                                 # FatOffset = ClusterNumber * 2
 156         pushw   %si                                 # Save si
 157         movw    %ax, %si                            # si = FatOffset
 158         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 159         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 160         andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
 161         cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
 162         je      SkipFatRead
 163         movw    $2, %bx
 164         pushw   %es
 165         pushw   %ds
 166         popw    %es
 167         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 168         popw    %es
 169         movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
 170 SkipFatRead:
 171         movw    (%si), %bx                          # bx = NextClusterNumber
 172         movw    %cx, %ax                            # ax = ClusterNumber
 173         popw    %si                                 # Restore si
 174         decw    %bx                                 # bx = NextClusterNumber - 1
 175         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 176         jne     ReadClusters
 177         incw    %bx                                 # bx = NextClusterNumber
 178         incw    %si                                 # NumberOfClusters++
 179         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 180         jmp     FatChainLoop
 181 ReadClusters:
 182         incw    %bx
 183         popw    %ax                                 # ax = StartCluster
 184         pushw   %bx                                 # StartCluster = NextClusterNumber
 185         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 186         subw    $2, %ax                             # ax = StartCluster - 2
 187         xorb    %bh, %bh
 188         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 189         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 190         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 191         pushw   %ax                                 # save start sector
 192         movw    %si, %ax                            # ax = NumberOfClusters
 193         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 194         movw    %ax, %bx                            # bx = Number of Sectors
 195         popw    %ax                                 # ax = Start Sector
 196         call    ReadBlocks
 197         movw    $1, %si                             # NumberOfClusters = 1
 198         jmp     FatChainLoop
 199 FoundLastCluster:
 200         popw    %cx
 201         popa
 202         ret
 203
 204
 205 # ****************************************************************************
 206 # ReadBlocks - Reads a set of blocks from a block device
 207 #
 208 # AX    = Start LBA
 209 # BX    = Number of Blocks to Read
 210 # ES:DI = Buffer to store sectors read from disk
 211 # ****************************************************************************
 212
 213 # cx = Blocks
 214 # bx = NumberOfBlocks
 215 # si = StartLBA
 216
 217 ReadBlocks:
 218         pusha
 219         addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
 220         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 221         movl    %eax, %esi                          # esi = Start LBA
 222         movw    %bx, %cx                            # cx = Number of blocks to read
 223 ReadCylinderLoop:
 224         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 225         movl    %esi, %eax                          # eax = Start LBA
 226         xorl    %edx, %edx                          # edx = 0
 227         movzwl  (%bp), %ebx                         # bx = MaxSector
 228         divl    %ebx                                # ax = StartLBA / MaxSector
 229         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 230
 231         movw    (%bp), %bx                          # bx = MaxSector
 232         subw    %dx, %bx                            # bx = MaxSector - Sector
 233         incw    %bx                                 # bx = MaxSector - Sector + 1
 234         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 235         jg      LimitTransfer
 236         movw    %cx, %bx                            # bx = Blocks
 237 LimitTransfer:
 238         pushw   %ax                                 # save ax
 239         movw    %es, %ax                            # ax = es
 240         shrw    $(BLOCK_SHIFT-4), %ax               # ax = Number of blocks into mem system
 241         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 242         addw    %bx, %ax                            # ax = End Block number of transfer
 243         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 244         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 245         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 246         subw    %ax, %bx                            # Decrease transfer size by block overage
 247 NotCrossing64KBoundry:
 248         popw    %ax                                 # restore ax
 249
 250         pushw   %cx
 251         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 252         xorw    %dx, %dx                            # dx = 0
 253         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 254                                                     # dx = ax % (MaxHead + 1) = Head
 255
 256         pushw   %bx                                 # Save number of blocks to transfer
 257         movb    %dl, %dh                            # dh = Head
 258         movw    $0x7c00, %bp                        # bp = 0x7c00
 259         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 260         movb    %al, %ch                            # ch = Cylinder
 261         movb    %bl, %al                            # al = Blocks
 262         movb    $2, %ah                             # ah = Function 2
 263         movw    %di, %bx                            # es:bx = Buffer address
 264         int     $0x13
 265         jc      DiskError
 266         popw    %bx
 267         popw    %cx
 268         movzwl  %bx, %ebx
 269         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 270         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 271         movw    %es, %ax
 272         shlw    $(BLOCK_SHIFT-4), %bx
 273         addw    %bx, %ax
 274         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 275         cmpw    $0, %cx
 276         jne     ReadCylinderLoop
 277         popa
 278         ret
 279
 280 DiskError:
 281         pushw %cs
 282         popw %ds
 283         leaw ErrorString, %si
 284         movw $7, %cx
 285         jmp  PrintStringAndHalt
 286
 287 PrintStringAndHalt:
 288         movw $0xb800, %ax
 289         movw %ax, %es
 290         movw $160, %di
 291         rep
 292         movsw
 293 Halt:
 294         jmp   Halt
 295
 296 ErrorString:
 297         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
 298
 299         # .org     0x01fa # Just for passing build.
 300 LBAOffsetForBootSector:
 301         .long   0x0
 302
 303         # .org     0x01fe # Just for passing build.
 304         .word   0xaa55
 305
 306 #******************************************************************************
 307 #******************************************************************************
 308 #******************************************************************************
 309
 310 .equ                 DELAY_PORT,            0x0ed     # Port to use for 1uS delay
 311 .equ                 KBD_CONTROL_PORT,      0x060     # 8042 control port
 312 .equ                 KBD_STATUS_PORT,       0x064     # 8042 status port
 313 .equ                 WRITE_DATA_PORT_CMD,   0x0d1     # 8042 command to write the data port
 314 .equ                 ENABLE_A20_CMD,        0x0df     # 8042 command to enable A20
 315
 316         # .org     0x0200 # Just for passing build.
 317         jmp start
 318 Em64String:
 319         .byte 'E', 0x0c, 'm', 0x0c, '6', 0x0c, '4', 0x0c, 'T', 0x0c, ' ', 0x0c, 'U', 0x0c, 'n', 0x0c, 's', 0x0c, 'u', 0x0c, 'p', 0x0c, 'p', 0x0c, 'o', 0x0c, 'r', 0x0c, 't', 0x0c, 'e', 0x0c, 'd', 0x0c, '!', 0x0c
 320
 321 start:
 322         movw %cs, %ax
 323         movw %ax, %ds
 324         movw %ax, %es
 325         movw %ax, %ss
 326         movw $MyStack, %sp
 327
 328 #        mov ax,0b800h
 329 #        mov es,ax
 330 #        mov byte ptr es:[160],'a'
 331 #        mov ax,cs
 332 #        mov es,ax
 333
 334         movl $0, %ebx
 335         leal MemoryMap, %edi
 336 MemMapLoop:
 337         movl $0xe820, %eax
 338         movl $20, %ecx
 339         movl $0x534d4150, %edx  # 0x534d4150  stands for 'SMAP'
 340         int $0x15
 341         jc  MemMapDone
 342         addl $20, %edi
 343         cmpl $0, %ebx
 344         je  MemMapDone
 345         jmp MemMapLoop
 346 MemMapDone:
 347         leal MemoryMap, %eax
 348         subl %eax, %edi                     # Get the address of the memory map
 349         movl %edi, MemoryMapSize            # Save the size of the memory map
 350
 351         xorl    %ebx, %ebx
 352         movw    %cs, %bx                    # BX=segment
 353         shll    $4, %ebx                    # BX="linear" address of segment base
 354         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 355         movl    %eax, gdtr + 2              # Put address of gdt into the gdtr
 356         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 357         movl    %eax, idtr + 2              # Put address of idt into the idtr
 358         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 359
 360         addl $0x1000, %ebx                  # Source of EFI32
 361         movl %ebx, JUMP+2
 362         addl $0x1000, %ebx
 363         movl %ebx, %esi                     # Source of EFILDR32
 364
 365 #        mov ax,0b800h
 366 #        mov es,ax
 367 #        mov byte ptr es:[162],'b'
 368 #        mov ax,cs
 369 #        mov es,ax
 370
 371 #
 372 # Enable A20 Gate
 373 #
 374
 375         movw $0x2401, %ax                   # Enable A20 Gate
 376         int $0x15
 377         jnc A20GateEnabled                  # Jump if it suceeded
 378
 379 #
 380 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 381 #
 382
 383         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 384         jnz     Timeout8042                 # Jump if the 8042 timed out
 385         outw    %ax, $DELAY_PORT            # Delay 1 uS
 386         movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 387         outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
 388         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 389         jnz     Timeout8042                 # Jump if the 8042 timed out
 390         movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
 391         outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 392         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 393         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 394 Delay25uS:
 395         outw    %ax, $DELAY_PORT            # Delay 1 uS
 396         loop    Delay25uS
 397 Timeout8042:
 398
 399
 400 A20GateEnabled:
 401         movw    $0x0008, %bx                # Flat data descriptor
 402 #
 403 # DISABLE INTERRUPTS - Entering Protected Mode
 404 #
 405
 406         cli
 407
 408 #        mov ax,0b800h
 409 #        mov es,ax
 410 #        mov byte ptr es:[164],'c'
 411 #        mov ax,cs
 412 #        mov es,ax
 413
 414         .byte   0x66
 415         lgdt    gdtr
 416         .byte   0x66
 417         lidt    idtr
 418
 419         movl    %cr0, %eax
 420         orb     $1, %al
 421         movl    %eax, %cr0
 422 JUMP:
 423 # jmp far 0010:00020000
 424         .byte 0x66
 425         .byte 0xea
 426         .long 0x00020000
 427         .word 0x0010
 428
 429 Empty8042InputBuffer:
 430         movw $0, %cx
 431 Empty8042Loop:
 432         outw    %ax, $DELAY_PORT            # Delay 1us
 433         inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 434         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 435         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 436         ret
 437
 438 ##############################################################################
 439 # data
 440 ##############################################################################
 441
 442         .p2align 1
 443
 444 gdtr:   .word  GDT_END - GDT_BASE - 1       # GDT limit
 445         .long 0                             # (GDT base gets set above)
 446 ##############################################################################
 447 #   global descriptor table (GDT)
 448 ##############################################################################
 449
 450         .p2align 1
 451
 452 GDT_BASE:
 453 # null descriptor
 454 .equ                NULL_SEL, .-GDT_BASE
 455         .word 0         # limit 15:0
 456         .word 0         # base 15:0
 457         .byte 0         # base 23:16
 458         .byte 0         # type
 459         .byte 0         # limit 19:16, flags
 460         .byte 0         # base 31:24
 461
 462 # linear data segment descriptor
 463 .equ            LINEAR_SEL, .-GDT_BASE
 464         .word 0xFFFF    # limit 0xFFFFF
 465         .word 0         # base 0
 466         .byte 0
 467         .byte 0x92      # present, ring 0, data, expand-up, writable
 468         .byte 0xCF              # page-granular, 32-bit
 469         .byte 0
 470
 471 # linear code segment descriptor
 472 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 473         .word 0xFFFF    # limit 0xFFFFF
 474         .word 0         # base 0
 475         .byte 0
 476         .byte 0x9A      # present, ring 0, data, expand-up, writable
 477         .byte 0xCF              # page-granular, 32-bit
 478         .byte 0
 479
 480 # system data segment descriptor
 481 .equ            SYS_DATA_SEL, .-GDT_BASE
 482         .word 0xFFFF    # limit 0xFFFFF
 483         .word 0         # base 0
 484         .byte 0
 485         .byte 0x92      # present, ring 0, data, expand-up, writable
 486         .byte 0xCF              # page-granular, 32-bit
 487         .byte 0
 488
 489 # system code segment descriptor
 490 .equ            SYS_CODE_SEL, .-GDT_BASE
 491         .word 0xFFFF    # limit 0xFFFFF
 492         .word 0         # base 0
 493         .byte 0
 494         .byte 0x9A      # present, ring 0, data, expand-up, writable
 495         .byte 0xCF              # page-granular, 32-bit
 496         .byte 0
 497
 498 # spare segment descriptor
 499 .equ        SPARE3_SEL, .-GDT_BASE
 500         .word 0         # limit 0xFFFFF
 501         .word 0         # base 0
 502         .byte 0
 503         .byte 0         # present, ring 0, data, expand-up, writable
 504         .byte 0         # page-granular, 32-bit
 505         .byte 0
 506
 507 # spare segment descriptor
 508 .equ        SPARE4_SEL, .-GDT_BASE
 509         .word 0         # limit 0xFFFFF
 510         .word 0         # base 0
 511         .byte 0
 512         .byte 0         # present, ring 0, data, expand-up, writable
 513         .byte 0         # page-granular, 32-bit
 514         .byte 0
 515
 516 # spare segment descriptor
 517 .equ        SPARE5_SEL, .-GDT_BASE
 518         .word 0         # limit 0xFFFFF
 519         .word 0         # base 0
 520         .byte 0
 521         .byte 0         # present, ring 0, data, expand-up, writable
 522         .byte 0         # page-granular, 32-bit
 523         .byte 0
 524
 525 GDT_END:
 526
 527         .p2align 1
 528
 529
 530
 531 idtr:   .word IDT_END - IDT_BASE - 1  # IDT limit
 532         .long 0                       # (IDT base gets set above)
 533 ##############################################################################
 534 #   interrupt descriptor table (IDT)
 535 #
 536 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 537 #       mappings.  This implementation only uses the system timer and all other
 538 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 539 #       for convenience.
 540 ##############################################################################
 541
 542 #idt_tag db "IDT",0
 543         .p2align 1
 544
 545 IDT_BASE:
 546 # divide by zero (INT 0)
 547 .equ                DIV_ZERO_SEL, .-IDT_BASE
 548         .word 0             # offset 15:0
 549         .word SYS_CODE_SEL  # selector 15:0
 550         .byte 0             # 0 for interrupt gate
 551         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 552         .word 0             # offset 31:16
 553
 554 # debug exception (INT 1)
 555 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 556         .word 0             # offset 15:0
 557         .word SYS_CODE_SEL  # selector 15:0
 558         .byte 0             # 0 for interrupt gate
 559         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 560         .word 0             # offset 31:16
 561
 562 # NMI (INT 2)
 563 .equ                NMI_SEL, .-IDT_BASE
 564         .word 0             # offset 15:0
 565         .word SYS_CODE_SEL  # selector 15:0
 566         .byte 0             # 0 for interrupt gate
 567         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 568         .word 0             # offset 31:16
 569
 570 # soft breakpoint (INT 3)
 571 .equ                BREAKPOINT_SEL, .-IDT_BASE
 572         .word 0             # offset 15:0
 573         .word SYS_CODE_SEL  # selector 15:0
 574         .byte 0             # 0 for interrupt gate
 575         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 576         .word 0             # offset 31:16
 577
 578 # overflow (INT 4)
 579 .equ                OVERFLOW_SEL, .-IDT_BASE
 580         .word 0             # offset 15:0
 581         .word SYS_CODE_SEL  # selector 15:0
 582         .byte 0             # 0 for interrupt gate
 583         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 584         .word 0             # offset 31:16
 585
 586 # bounds check (INT 5)
 587 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 588         .word 0             # offset 15:0
 589         .word SYS_CODE_SEL  # selector 15:0
 590         .byte 0             # 0 for interrupt gate
 591         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 592         .word 0             # offset 31:16
 593
 594 # invalid opcode (INT 6)
 595 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 596         .word 0             # offset 15:0
 597         .word SYS_CODE_SEL  # selector 15:0
 598         .byte 0             # 0 for interrupt gate
 599         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 600         .word 0             # offset 31:16
 601
 602 # device not available (INT 7)
 603 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 604         .word 0             # offset 15:0
 605         .word SYS_CODE_SEL  # selector 15:0
 606         .byte 0             # 0 for interrupt gate
 607         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 608         .word 0             # offset 31:16
 609
 610 # double fault (INT 8)
 611 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 612         .word 0             # offset 15:0
 613         .word SYS_CODE_SEL  # selector 15:0
 614         .byte 0             # 0 for interrupt gate
 615         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 616         .word 0             # offset 31:16
 617
 618 # Coprocessor segment overrun - reserved (INT 9)
 619 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 620         .word 0             # offset 15:0
 621         .word SYS_CODE_SEL  # selector 15:0
 622         .byte 0             # 0 for interrupt gate
 623         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 624         .word 0             # offset 31:16
 625
 626 # invalid TSS (INT 0ah)
 627 .equ                INVALID_TSS_SEL, .-IDT_BASE
 628         .word 0             # offset 15:0
 629         .word SYS_CODE_SEL  # selector 15:0
 630         .byte 0             # 0 for interrupt gate
 631         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 632         .word 0             # offset 31:16
 633
 634 # segment not present (INT 0bh)
 635 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 636         .word 0             # offset 15:0
 637         .word SYS_CODE_SEL  # selector 15:0
 638         .byte 0             # 0 for interrupt gate
 639         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 640         .word 0             # offset 31:16
 641
 642 # stack fault (INT 0ch)
 643 .equ                STACK_FAULT_SEL, .-IDT_BASE
 644         .word 0             # offset 15:0
 645         .word SYS_CODE_SEL  # selector 15:0
 646         .byte 0             # 0 for interrupt gate
 647         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 648         .word 0             # offset 31:16
 649
 650 # general protection (INT 0dh)
 651 .equ                GP_FAULT_SEL, .-IDT_BASE
 652         .word 0             # offset 15:0
 653         .word SYS_CODE_SEL  # selector 15:0
 654         .byte 0             # 0 for interrupt gate
 655         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 656         .word 0             # offset 31:16
 657
 658 # page fault (INT 0eh)
 659 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 660         .word 0             # offset 15:0
 661         .word SYS_CODE_SEL  # selector 15:0
 662         .byte 0             # 0 for interrupt gate
 663         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 664         .word 0             # offset 31:16
 665
 666 # Intel reserved - do not use (INT 0fh)
 667 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 668         .word 0             # offset 15:0
 669         .word SYS_CODE_SEL  # selector 15:0
 670         .byte 0             # 0 for interrupt gate
 671         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 672         .word 0             # offset 31:16
 673
 674 # floating point error (INT 10h)
 675 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 676         .word 0             # offset 15:0
 677         .word SYS_CODE_SEL  # selector 15:0
 678         .byte 0             # 0 for interrupt gate
 679         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 680         .word 0             # offset 31:16
 681
 682 # alignment check (INT 11h)
 683 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 684         .word 0             # offset 15:0
 685         .word SYS_CODE_SEL  # selector 15:0
 686         .byte 0             # 0 for interrupt gate
 687         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 688         .word 0             # offset 31:16
 689
 690 # machine check (INT 12h)
 691 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 692         .word 0             # offset 15:0
 693         .word SYS_CODE_SEL  # selector 15:0
 694         .byte 0             # 0 for interrupt gate
 695         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 696         .word 0             # offset 31:16
 697
 698 # SIMD floating-point exception (INT 13h)
 699 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 700         .word 0             # offset 15:0
 701         .word SYS_CODE_SEL  # selector 15:0
 702         .byte 0             # 0 for interrupt gate
 703         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 704         .word 0             # offset 31:16
 705
 706 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 707         .fill  85 * 8, 1, 0
 708
 709 # IRQ 0 (System timer) - (INT 68h)
 710 .equ                IRQ0_SEL, .-IDT_BASE
 711         .word 0             # offset 15:0
 712         .word SYS_CODE_SEL  # selector 15:0
 713         .byte 0             # 0 for interrupt gate
 714         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 715         .word 0             # offset 31:16
 716
 717 # IRQ 1 (8042 Keyboard controller) - (INT 69h)
 718 .equ                IRQ1_SEL, .-IDT_BASE
 719         .word 0             # offset 15:0
 720         .word SYS_CODE_SEL  # selector 15:0
 721         .byte 0             # 0 for interrupt gate
 722         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 723         .word 0             # offset 31:16
 724
 725 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
 726 .equ                IRQ2_SEL, .-IDT_BASE
 727         .word 0             # offset 15:0
 728         .word SYS_CODE_SEL  # selector 15:0
 729         .byte 0             # 0 for interrupt gate
 730         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 731         .word 0             # offset 31:16
 732
 733 # IRQ 3 (COM 2) - (INT 6bh)
 734 .equ                IRQ3_SEL, .-IDT_BASE
 735         .word 0             # offset 15:0
 736         .word SYS_CODE_SEL  # selector 15:0
 737         .byte 0             # 0 for interrupt gate
 738         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 739         .word 0             # offset 31:16
 740
 741 # IRQ 4 (COM 1) - (INT 6ch)
 742 .equ                IRQ4_SEL, .-IDT_BASE
 743         .word 0             # offset 15:0
 744         .word SYS_CODE_SEL  # selector 15:0
 745         .byte 0             # 0 for interrupt gate
 746         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 747         .word 0             # offset 31:16
 748
 749 # IRQ 5 (LPT 2) - (INT 6dh)
 750 .equ                IRQ5_SEL, .-IDT_BASE
 751         .word 0             # offset 15:0
 752         .word SYS_CODE_SEL  # selector 15:0
 753         .byte 0             # 0 for interrupt gate
 754         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 755         .word 0             # offset 31:16
 756
 757 # IRQ 6 (Floppy controller) - (INT 6eh)
 758 .equ                IRQ6_SEL, .-IDT_BASE
 759         .word 0             # offset 15:0
 760         .word SYS_CODE_SEL  # selector 15:0
 761         .byte 0             # 0 for interrupt gate
 762         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 763         .word 0             # offset 31:16
 764
 765 # IRQ 7 (LPT 1) - (INT 6fh)
 766 .equ                IRQ7_SEL, .-IDT_BASE
 767         .word 0             # offset 15:0
 768         .word SYS_CODE_SEL  # selector 15:0
 769         .byte 0             # 0 for interrupt gate
 770         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 771         .word 0             # offset 31:16
 772
 773 # IRQ 8 (RTC Alarm) - (INT 70h)
 774 .equ                IRQ8_SEL, .-IDT_BASE
 775         .word 0             # offset 15:0
 776         .word SYS_CODE_SEL  # selector 15:0
 777         .byte 0             # 0 for interrupt gate
 778         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 779         .word 0             # offset 31:16
 780
 781 # IRQ 9 - (INT 71h)
 782 .equ                IRQ9_SEL, .-IDT_BASE
 783         .word 0             # offset 15:0
 784         .word SYS_CODE_SEL  # selector 15:0
 785         .byte 0             # 0 for interrupt gate
 786         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 787         .word 0             # offset 31:16
 788
 789 # IRQ 10 - (INT 72h)
 790 .equ                 IRQ10_SEL, .-IDT_BASE
 791         .word 0             # offset 15:0
 792         .word SYS_CODE_SEL  # selector 15:0
 793         .byte 0             # 0 for interrupt gate
 794         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 795         .word 0             # offset 31:16
 796
 797 # IRQ 11 - (INT 73h)
 798 .equ                 IRQ11_SEL, .-IDT_BASE
 799         .word 0             # offset 15:0
 800         .word SYS_CODE_SEL  # selector 15:0
 801         .byte 0             # 0 for interrupt gate
 802         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 803         .word 0             # offset 31:16
 804
 805 # IRQ 12 (PS/2 mouse) - (INT 74h)
 806 .equ                 IRQ12_SEL, .-IDT_BASE
 807         .word 0             # offset 15:0
 808         .word SYS_CODE_SEL  # selector 15:0
 809         .byte 0             # 0 for interrupt gate
 810         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 811         .word 0             # offset 31:16
 812
 813 # IRQ 13 (Floating point error) - (INT 75h)
 814 .equ                 IRQ13_SEL, .-IDT_BASE
 815         .word 0             # offset 15:0
 816         .word SYS_CODE_SEL  # selector 15:0
 817         .byte 0             # 0 for interrupt gate
 818         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 819         .word 0             # offset 31:16
 820
 821 # IRQ 14 (Secondary IDE) - (INT 76h)
 822 .equ                 IRQ14_SEL, .-IDT_BASE
 823         .word 0             # offset 15:0
 824         .word SYS_CODE_SEL  # selector 15:0
 825         .byte 0             # 0 for interrupt gate
 826         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 827         .word 0             # offset 31:16
 828
 829 # IRQ 15 (Primary IDE) - (INT 77h)
 830 .equ                 IRQ15_SEL, .-IDT_BASE
 831         .word 0             # offset 15:0
 832         .word SYS_CODE_SEL  # selector 15:0
 833         .byte 0             # 0 for interrupt gate
 834         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 835         .word 0             # offset 31:16
 836
 837 IDT_END:
 838
 839         .p2align 1
 840
 841 MemoryMapSize:  .long 0
 842 MemoryMap:  .long 0,0,0,0,0,0,0,0
 843         .long 0,0,0,0,0,0,0,0
 844         .long 0,0,0,0,0,0,0,0
 845         .long 0,0,0,0,0,0,0,0
 846         .long 0,0,0,0,0,0,0,0
 847         .long 0,0,0,0,0,0,0,0
 848         .long 0,0,0,0,0,0,0,0
 849         .long 0,0,0,0,0,0,0,0
 850         .long 0,0,0,0,0,0,0,0
 851         .long 0,0,0,0,0,0,0,0
 852         .long 0,0,0,0,0,0,0,0
 853         .long 0,0,0,0,0,0,0,0
 854         .long 0,0,0,0,0,0,0,0
 855         .long 0,0,0,0,0,0,0,0
 856         .long 0,0,0,0,0,0,0,0
 857         .long 0,0,0,0,0,0,0,0
 858         .long 0,0,0,0,0,0,0,0
 859         .long 0,0,0,0,0,0,0,0
 860         .long 0,0,0,0,0,0,0,0
 861         .long 0,0,0,0,0,0,0,0
 862         .long 0,0,0,0,0,0,0,0
 863         .long 0,0,0,0,0,0,0,0
 864         .long 0,0,0,0,0,0,0,0
 865         .long 0,0,0,0,0,0,0,0
 866         .long 0,0,0,0,0,0,0,0
 867         .long 0,0,0,0,0,0,0,0
 868         .long 0,0,0,0,0,0,0,0
 869         .long 0,0,0,0,0,0,0,0
 870         .long 0,0,0,0,0,0,0,0
 871         .long 0,0,0,0,0,0,0,0
 872
 873         .long 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
 874         .long 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
 875
 876         .org 0x0fe0
 877 MyStack:
 878         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 879         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 880         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 881         #    8259.c
 882
 883         int $8
 884         iret
 885
 886         int $9
 887         iret
 888
 889         int $10
 890         iret
 891
 892         int $11
 893         iret
 894
 895         int $12
 896         iret
 897
 898         int $13
 899         iret
 900
 901         int $14
 902         iret
 903
 904         int $15
 905         iret
 906
 907
 908         .org 0x0ffe
 909 BlockSignature:
 910         .word 0xaa55