DuetPkg/BootSector/start.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 #*    start.S
  13 #*
  14 #*   Abstract:
  15 #*
  16 #------------------------------------------------------------------------------
  17
  18         .stack:
  19         .486p:
  20         .code16
  21
  22 .equ                        FAT_DIRECTORY_ENTRY_SIZE, 0x020
  23 .equ                        FAT_DIRECTORY_ENTRY_SHIFT, 5
  24 .equ                        BLOCK_SIZE, 0x0200
  25 .equ                        BLOCK_MASK, 0x01ff
  26 .equ                        BLOCK_SHIFT, 9
  27
  28        .org 0x0
  29
  30 .global _start
  31 _start:
  32
  33 Ia32Jump:
  34   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  35   nop
  36
  37 OemId:              .ascii   "INTEL   "       # OemId               - 8 bytes
  38
  39 SectorSize:         .word  0                  # Sector Size         - 16 bits
  40 SectorsPerCluster:  .byte  0                  # Sector Per Cluster  - 8 bits
  41 ReservedSectors:    .word  0                  # Reserved Sectors    - 16 bits
  42 NoFats:             .byte  0                  # Number of FATs      - 8 bits
  43 RootEntries:        .word  0                  # Root Entries        - 16 bits
  44 Sectors:            .word  0                  # Number of Sectors   - 16 bits
  45 Media:              .byte  0                  # Media               - 8 bits  - ignored
  46 SectorsPerFat:      .word  0                  # Sectors Per FAT     - 16 bits
  47 SectorsPerTrack:    .word  0                  # Sectors Per Track   - 16 bits - ignored
  48 Heads:              .word  0                  # Heads               - 16 bits - ignored
  49 HiddenSectors:      .long  0                  # Hidden Sectors      - 32 bits - ignored
  50 LargeSectors:       .long  0                  # Large Sectors       - 32 bits
  51 PhysicalDrive:      .byte  0                  # PhysicalDriveNumber - 8 bits  - ignored
  52 CurrentHead:        .byte  0                  # Current Head        - 8 bits
  53 Signature:          .byte  0                  # Signature           - 8 bits  - ignored
  54 VolId:              .ascii "    "             # Volume Serial Number- 4 bytes
  55 FatLabel:           .ascii "           "      # Label               - 11 bytes
  56 SystemId:           .ascii "FAT12   "         # SystemId            - 8 bytes
  57
  58 BootSectorEntryPoint:
  59         #ASSUME ds:@code
  60         #ASSUME ss:@code
  61       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  62       # cx = Start Cluster of EfiLdr
  63       # dx = Start Cluster of Efivar.bin
  64
  65 # Re use the BPB data stored in Boot Sector
  66         movw    $0x7c00, %bp
  67
  68         pushw   %cx
  69 # Read Efivar.bin
  70 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  71         movw    $0x1900, %ax
  72         movw    %ax, %es
  73         testw   %dx, %dx
  74         jnz     CheckVarStoreSize
  75
  76         movb    $1, %al
  77 NoVarStore:
  78         pushw   %es
  79 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  80         movb    %al, %es:(4)
  81         jmp     SaveVolumeId
  82
  83 CheckVarStoreSize:
  84         movw    %dx, %di
  85         cmpl    $0x4000, %ds:2(%di)
  86         movb    $2, %al
  87         jne     NoVarStore
  88
  89 LoadVarStore:
  90         movb    $0, %al
  91         movb    %al, %es:(4)
  92         movw    (%di), %cx
  93 #       ES:DI = 1500:0
  94         xorw    %di, %di
  95         pushw   %es
  96         movw    $0x1500, %ax
  97         movw    %ax, %es
  98         call    ReadFile
  99 SaveVolumeId:
 100         popw    %es
 101         movw    VolId(%bp), %ax
 102         movw    %ax, %es:(0)                    # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 103         movw    VolId+2(%bp), %ax
 104         movw    %ax, %es:(2)
 105
 106 # Read Efildr
 107         popw    %cx
 108 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 109 #       ES:DI = 2000:0, first cluster will be read again
 110         xorw    %di, %di                            # di = 0
 111         movw    $0x2000, %ax
 112         movw    %ax, %es
 113         call    ReadFile
 114         movw    %cs, %ax
 115         movw    %ax, %cs:JumpSegment
 116
 117 JumpFarInstruction:
 118         .byte   0xea
 119 JumpOffset:
 120         .word   0x200
 121 JumpSegment:
 122         .word   0x2000
 123
 124
 125
 126 # ****************************************************************************
 127 # ReadFile
 128 #
 129 # Arguments:
 130 #   CX    = Start Cluster of File
 131 #   ES:DI = Buffer to store file content read from disk
 132 #
 133 # Return:
 134 #   (ES << 4 + DI) = end of file content Buffer
 135 #
 136 # ****************************************************************************
 137 ReadFile:
 138 # si      = NumberOfClusters
 139 # cx      = ClusterNumber
 140 # dx      = CachedFatSectorNumber
 141 # ds:0000 = CacheFatSectorBuffer
 142 # es:di   = Buffer to load file
 143 # bx      = NextClusterNumber
 144         pusha
 145         movw    $1, %si                             # NumberOfClusters = 1
 146         pushw   %cx                                 # Push Start Cluster onto stack
 147         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 148 FatChainLoop:
 149         movw    %cx, %ax                            # ax = ClusterNumber
 150         andw    $0xff8, %ax                         # ax = ax & 0xff8
 151         cmpw    $0xff8, %ax                         # See if this is the last cluster
 152         je      FoundLastCluster                    # Jump if last cluster found
 153         movw    %cx, %ax                            # ax = ClusterNumber
 154         shlw    %ax                                 # ax = ClusterNumber * 2
 155         addw    %cx, %ax                            # ax = ClusterNumber * 2 + ClusterNumber = ClusterNumber * 3
 156         shrw    %ax                                 # FatOffset = ClusterNumber*3 / 2
 157         pushw   %si                                 # Save si
 158         movw    %ax, %si                            # si = FatOffset
 159         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 160         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 161         andw    $BLOCK_MASK,%si                     # si = FatOffset & BLOCK_MASK
 162         cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
 163         je      SkipFatRead
 164         movw    $2, %bx
 165         pushw   %es
 166         pushw   %ds
 167         popw    %es
 168         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 169         popw    %es
 170         movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
 171 SkipFatRead:
 172         movw    (%si), %bx                          # bx = NextClusterNumber
 173         movw    %cx, %ax                            # ax = ClusterNumber
 174         andw    $1, %ax                             # See if this is an odd cluster number
 175         je      EvenFatEntry
 176         shrw    $4, %bx                             # NextClusterNumber = NextClusterNumber >> 4
 177 EvenFatEntry:
 178         andw    $0xfff, %bx                         # Strip upper 4 bits of NextClusterNumber
 179         popw    %si                                 # Restore si
 180         decw    %bx                                 # bx = NextClusterNumber - 1
 181         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 182         jne     ReadClusters
 183         incw    %bx                                 # bx = NextClusterNumber
 184         incw    %si                                 # NumberOfClusters++
 185         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 186         jmp     FatChainLoop
 187 ReadClusters:
 188         incw    %bx
 189         popw    %ax                                 # ax = StartCluster
 190         pushw   %bx                                 # StartCluster = NextClusterNumber
 191         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 192         subw    $2, %ax                             # ax = StartCluster - 2
 193         xorb    %bh, %bh
 194         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 195         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 196         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 197         pushw   %ax                                 # save start sector
 198         movw    %si, %ax                            # ax = NumberOfClusters
 199         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 200         movw    %ax, %bx                            # bx = Number of Sectors
 201         popw    %ax                                 # ax = Start Sector
 202         call    ReadBlocks
 203         movw    $1, %si                             # NumberOfClusters = 1
 204         jmp     FatChainLoop
 205 FoundLastCluster:
 206         popw    %cx
 207         popa
 208         ret
 209
 210
 211 # ****************************************************************************
 212 # ReadBlocks - Reads a set of blocks from a block device
 213 #
 214 # AX    = Start LBA
 215 # BX    = Number of Blocks to Read
 216 # ES:DI = Buffer to store sectors read from disk
 217 # ****************************************************************************
 218
 219 # cx = Blocks
 220 # bx = NumberOfBlocks
 221 # si = StartLBA
 222
 223 ReadBlocks:
 224         pusha
 225         addl    LBAOffsetForBootSector(%bp), %eax   # Add LBAOffsetForBootSector to Start LBA
 226         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 227         movl    %eax, %esi                          # esi = Start LBA
 228         movw    %bx, %cx                            # cx = Number of blocks to read
 229 ReadCylinderLoop:
 230         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 231         movl    %esi, %eax                          # eax = Start LBA
 232         xorl    %edx, %edx                          # edx = 0
 233         movzwl  (%bp), %ebx                         # bx = MaxSector
 234         divl    %ebx                                # ax = StartLBA / MaxSector
 235         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 236
 237         movw    (%bp), %bx                          # bx = MaxSector
 238         subw    %dx, %bx                            # bx = MaxSector - Sector
 239         incw    %bx                                 # bx = MaxSector - Sector + 1
 240         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 241         jg      LimitTransfer
 242         movw    %cx, %bx                            # bx = Blocks
 243 LimitTransfer:
 244         pushw   %ax                                 # save ax
 245         movw    %es, %ax                            # ax = es
 246         shrw    $(BLOCK_SHIFT-4), %ax               # ax = Number of blocks into mem system
 247         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 248         addw    %bx, %ax                            # ax = End Block number of transfer
 249         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 250         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 251         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 252         subw    %ax, %bx                            # Decrease transfer size by block overage
 253 NotCrossing64KBoundry:
 254         popw    %ax                                 # restore ax
 255
 256         pushw   %cx
 257         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 258         xorw    %dx, %dx                            # dx = 0
 259         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 260                                                     # dx = ax % (MaxHead + 1) = Head
 261
 262         pushw   %bx                                 # Save number of blocks to transfer
 263         movb    %dl, %dh                            # dh = Head
 264         movw    $0x7c00, %bp                        # bp = 0x7c00
 265         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 266         movb    %al, %ch                            # ch = Cylinder
 267         movb    %bl, %al                            # al = Blocks
 268         movb    $2, %ah                             # ah = Function 2
 269         movw    %di, %bx                            # es:bx = Buffer address
 270         int     $0x13
 271         jc      DiskError
 272         popw    %bx
 273         popw    %cx
 274         movzwl  %bx, %ebx
 275         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 276         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 277         movw    %es, %ax
 278         shlw    $(BLOCK_SHIFT-4), %bx
 279         addw    %bx, %ax
 280         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 281         cmpw    $0, %cx
 282         jne     ReadCylinderLoop
 283         popa
 284         ret
 285
 286 DiskError:
 287         pushw %cs
 288         popw %ds
 289         leaw ErrorString, %si
 290         movw $7, %cx
 291         jmp  PrintStringAndHalt
 292
 293 PrintStringAndHalt:
 294         movw $0xb800, %ax
 295         movw %ax, %es
 296         movw $160, %di
 297         rep
 298         movsw
 299 Halt:
 300         jmp   Halt
 301
 302 ErrorString:
 303         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!',0x0c
 304
 305         .org     0x01fa
 306 LBAOffsetForBootSector:
 307         .long   0x0
 308
 309         .org    0x01fe
 310         .word   0xaa55
 311
 312 #******************************************************************************
 313 #******************************************************************************
 314 #******************************************************************************
 315
 316 .equ                 DELAY_PORT, 0x0ed           # Port to use for 1uS delay
 317 .equ                 KBD_CONTROL_PORT, 0x060     # 8042 control port
 318 .equ                 KBD_STATUS_PORT, 0x064      # 8042 status port
 319 .equ                 WRITE_DATA_PORT_CMD, 0x0d1  # 8042 command to write the data port
 320 .equ                 ENABLE_A20_CMD, 0x0df       # 8042 command to enable A20
 321
 322         .org     0x200
 323         jmp start
 324 Em64String:
 325         .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
 326
 327 start:
 328         movw %cs, %ax
 329         movw %ax, %ds
 330         movw %ax, %es
 331         movw %ax, %ss
 332         movw $MyStack, %sp
 333
 334 #        mov ax,0b800h
 335 #        mov es,ax
 336 #        mov byte ptr es:[160],'a'
 337 #        mov ax,cs
 338 #        mov es,ax
 339
 340         movl $0, %ebx
 341         leal MemoryMap, %edi
 342 MemMapLoop:
 343         movl $0xe820, %eax
 344         movl $20, %ecx
 345         movl $0x534d4150, %edx  # SMAP
 346         int $0x15
 347         jc  MemMapDone
 348         addl $20, %edi
 349         cmpl $0, %ebx
 350         je  MemMapDone
 351         jmp MemMapLoop
 352 MemMapDone:
 353         leal MemoryMap, %eax
 354         subl %eax, %edi                     # Get the address of the memory map
 355         movl %edi, MemoryMapSize            # Save the size of the memory map
 356
 357         xorl    %ebx, %ebx
 358         movw    %cs, %bx                    # BX=segment
 359         shll    $4, %ebx                    # BX="linear" address of segment base
 360         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 361         movl    %eax, (gdtr + 2)            # Put address of gdt into the gdtr
 362         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 363         movl    %eax, (idtr + 2)            # Put address of idt into the idtr
 364         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 365
 366         addl $0x1000, %ebx                  # Source of EFI32
 367         movl %ebx, JUMP+2
 368         addl $0x1000, %ebx
 369         movl %ebx, %esi                     # Source of EFILDR32
 370
 371 #        mov ax,0b800h
 372 #        mov es,ax
 373 #        mov byte ptr es:[162],'b'
 374 #        mov ax,cs
 375 #        mov es,ax
 376
 377 #
 378 # Enable A20 Gate
 379 #
 380
 381         movw $0x2401, %ax                   # Enable A20 Gate
 382         int $0x15
 383         jnc A20GateEnabled                  # Jump if it suceeded
 384
 385 #
 386 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 387 #
 388
 389         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 390         jnz     Timeout8042                 # Jump if the 8042 timed out
 391         outw    %ax, $DELAY_PORT            # Delay 1 uS
 392         mov     $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 393         out     %al, $KBD_STATUS_PORT       # Send command to the 8042
 394         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 395         jnz     Timeout8042                 # Jump if the 8042 timed out
 396         mov     $ENABLE_A20_CMD, %al        # gate address bit 20 on
 397         out     %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 398         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 399         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 400 Delay25uS:
 401         outw    %ax, $DELAY_PORT            # Delay 1 uS
 402         loop    Delay25uS
 403 Timeout8042:
 404
 405
 406 A20GateEnabled:
 407         movw    $0x0008, %bx                # Flat data descriptor
 408
 409 #
 410 # DISABLE INTERRUPTS - Entering Protected Mode
 411 #
 412
 413         cli
 414
 415 #        mov ax,0b800h
 416 #        mov es,ax
 417 #        mov byte ptr es:[164],'c'
 418 #        mov ax,cs
 419 #        mov es,ax
 420
 421         .byte   0x66
 422         lgdt    gdtr
 423         .byte   0x66
 424         lidt    idtr
 425
 426         movl    %cr0, %eax
 427         orb     $1, %al
 428         movl    %eax, %cr0
 429 JUMP:
 430 # jmp far 0010:00020000
 431         .byte 0x66
 432         .byte 0xea
 433         .long 0x00020000
 434         .word 0x0010
 435
 436 Empty8042InputBuffer:
 437         movw $0, %cx
 438 Empty8042Loop:
 439         outw    %ax, $DELAY_PORT            # Delay 1us
 440         in      $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 441         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 442         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 443         ret
 444
 445 ##############################################################################
 446 # data
 447 ##############################################################################
 448
 449         .p2align 1
 450
 451         gdtr:    .long  GDT_END - GDT_BASE - 1  # GDT limit
 452         .long 0                                 # (GDT base gets set above)
 453 ##############################################################################
 454 #   global descriptor table (GDT)
 455 ##############################################################################
 456
 457         .p2align 1
 458
 459 GDT_BASE:
 460 # null descriptor
 461 .equ                NULL_SEL, .-GDT_BASE
 462         .word 0         # limit 15:0
 463         .word 0         # base 15:0
 464         .byte 0         # base 23:16
 465         .byte 0         # type
 466         .byte 0         # limit 19:16, flags
 467         .byte 0         # base 31:24
 468
 469 # linear data segment descriptor
 470 .equ            LINEAR_SEL, .-GDT_BASE
 471         .word 0xFFFF    # limit 0xFFFFF
 472         .word 0         # base 0
 473         .byte 0
 474         .byte 0x92      # present, ring 0, data, expand-up, writable
 475         .byte 0xCF              # page-granular, 32-bit
 476         .byte 0
 477
 478 # linear code segment descriptor
 479 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 480         .word 0xFFFF    # limit 0xFFFFF
 481         .word 0         # base 0
 482         .byte 0
 483         .byte 0x9A      # present, ring 0, data, expand-up, writable
 484         .byte 0xCF              # page-granular, 32-bit
 485         .byte 0
 486
 487 # system data segment descriptor
 488 .equ            SYS_DATA_SEL, .-GDT_BASE
 489         .word 0xFFFF    # limit 0xFFFFF
 490         .word 0         # base 0
 491         .byte 0
 492         .byte 0x92      # present, ring 0, data, expand-up, writable
 493         .byte 0xCF              # page-granular, 32-bit
 494         .byte 0
 495
 496 # system code segment descriptor
 497 .equ            SYS_CODE_SEL, .-GDT_BASE
 498         .word 0xFFFF    # limit 0xFFFFF
 499         .word 0         # base 0
 500         .byte 0
 501         .byte 0x9A      # present, ring 0, data, expand-up, writable
 502         .byte 0xCF              # page-granular, 32-bit
 503         .byte 0
 504
 505 # spare segment descriptor
 506 .equ        SPARE3_SEL, .-GDT_BASE
 507         .word 0         # limit 0xFFFFF
 508         .word 0         # base 0
 509         .byte 0
 510         .byte 0         # present, ring 0, data, expand-up, writable
 511         .byte 0         # page-granular, 32-bit
 512         .byte 0
 513
 514 # spare segment descriptor
 515 .equ        SPARE4_SEL, .-GDT_BASE
 516         .word 0         # limit 0xFFFFF
 517         .word 0         # base 0
 518         .byte 0
 519         .byte 0         # present, ring 0, data, expand-up, writable
 520         .byte 0         # page-granular, 32-bit
 521         .byte 0
 522
 523 # spare segment descriptor
 524 .equ        SPARE5_SEL, .-GDT_BASE
 525         .word 0         # limit 0xFFFFF
 526         .word 0         # base 0
 527         .byte 0
 528         .byte 0         # present, ring 0, data, expand-up, writable
 529         .byte 0         # page-granular, 32-bit
 530         .byte 0
 531
 532 GDT_END:
 533
 534         .p2align 1
 535
 536
 537
 538 idtr:  .long  IDT_END - IDT_BASE - 1 # IDT limit
 539         .long 0                      # (IDT base gets set above)
 540 ##############################################################################
 541 #   interrupt descriptor table (IDT)
 542 #
 543 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 544 #       mappings.  This implementation only uses the system timer and all other
 545 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 546 #       for convenience.
 547 ##############################################################################
 548
 549 #idt_tag db "IDT",0
 550         .p2align 1
 551
 552 IDT_BASE:
 553 # divide by zero (INT 0)
 554 .equ                DIV_ZERO_SEL, .-IDT_BASE
 555         .word 0            # offset 15:0
 556         .long SYS_CODE_SEL # selector 15:0
 557         .byte 0            # 0 for interrupt gate
 558         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 559         .word 0            # offset 31:16
 560
 561 # debug exception (INT 1)
 562 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 563         .word 0            # offset 15:0
 564         .long SYS_CODE_SEL # selector 15:0
 565         .byte 0            # 0 for interrupt gate
 566         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 567         .word 0            # offset 31:16
 568
 569 # NMI (INT 2)
 570 .equ                NMI_SEL, .-IDT_BASE
 571         .word 0            # offset 15:0
 572         .long SYS_CODE_SEL # selector 15:0
 573         .byte 0            # 0 for interrupt gate
 574         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 575         .word 0            # offset 31:16
 576
 577 # soft breakpoint (INT 3)
 578 .equ                BREAKPOINT_SEL, .-IDT_BASE
 579         .word 0            # offset 15:0
 580         .long SYS_CODE_SEL # selector 15:0
 581         .byte 0            # 0 for interrupt gate
 582         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 583         .word 0            # offset 31:16
 584
 585 # overflow (INT 4)
 586 .equ                OVERFLOW_SEL, .-IDT_BASE
 587         .word 0            # offset 15:0
 588         .long SYS_CODE_SEL # selector 15:0
 589         .byte 0            # 0 for interrupt gate
 590         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 591         .word 0            # offset 31:16
 592
 593 # bounds check (INT 5)
 594 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 595         .word 0            # offset 15:0
 596         .long SYS_CODE_SEL # selector 15:0
 597         .byte 0            # 0 for interrupt gate
 598         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 599         .word 0            # offset 31:16
 600
 601 # invalid opcode (INT 6)
 602 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 603         .word 0            # offset 15:0
 604         .long SYS_CODE_SEL # selector 15:0
 605         .byte 0            # 0 for interrupt gate
 606         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 607         .word 0            # offset 31:16
 608
 609 # device not available (INT 7)
 610 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 611          .word 0            # offset 15:0
 612         .long SYS_CODE_SEL # selector 15:0
 613         .byte 0            # 0 for interrupt gate
 614         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 615         .word 0            # offset 31:16
 616
 617 # double fault (INT 8)
 618 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 619         .word 0            # offset 15:0
 620         .long SYS_CODE_SEL # selector 15:0
 621         .byte 0            # 0 for interrupt gate
 622         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 623         .word 0            # offset 31:16
 624
 625 # Coprocessor segment overrun - reserved (INT 9)
 626 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 627         .word 0            # offset 15:0
 628         .long SYS_CODE_SEL # selector 15:0
 629         .byte 0            # 0 for interrupt gate
 630         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 631         .word 0            # offset 31:16
 632
 633 # invalid TSS (INT 0x0a)
 634 .equ                INVALID_TSS_SEL, .-IDT_BASE
 635         .word 0            # offset 15:0
 636         .long SYS_CODE_SEL # selector 15:0
 637         .byte 0            # 0 for interrupt gate
 638         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 639         .word 0            # offset 31:16
 640
 641 # segment not present (INT 0x0b)
 642 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 643         .word 0            # offset 15:0
 644         .long SYS_CODE_SEL # selector 15:0
 645         .byte 0            # 0 for interrupt gate
 646         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 647         .word 0            # offset 31:16
 648
 649 # stack fault (INT 0x0c)
 650 .equ                STACK_FAULT_SEL, .-IDT_BASE
 651         .word 0            # offset 15:0
 652         .long SYS_CODE_SEL # selector 15:0
 653         .byte 0            # 0 for interrupt gate
 654         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 655         .word 0            # offset 31:16
 656
 657 # general protection (INT 0x0d)
 658 .equ                GP_FAULT_SEL, .-IDT_BASE
 659         .word 0            # offset 15:0
 660         .long SYS_CODE_SEL # selector 15:0
 661         .byte 0            # 0 for interrupt gate
 662         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 663         .word 0            # offset 31:16
 664
 665 # page fault (INT 0x0e)
 666 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 667         .word 0            # offset 15:0
 668         .long SYS_CODE_SEL # selector 15:0
 669         .byte 0            # 0 for interrupt gate
 670         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 671         .word 0            # offset 31:16
 672
 673 # Intel reserved - do not use (INT 0x0f)
 674 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 675         .word 0            # offset 15:0
 676         .long SYS_CODE_SEL # selector 15:0
 677         .byte 0            # 0 for interrupt gate
 678         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 679         .word 0            # offset 31:16
 680
 681 # floating point error (INT 0x10)
 682 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 683         .word 0            # offset 15:0
 684         .long SYS_CODE_SEL # selector 15:0
 685         .byte 0            # 0 for interrupt gate
 686         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 687         .word 0            # offset 31:16
 688
 689 # alignment check (INT 0x11)
 690 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 691         .word 0            # offset 15:0
 692         .long SYS_CODE_SEL # selector 15:0
 693         .byte 0            # 0 for interrupt gate
 694         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 695         .word 0            # offset 31:16
 696
 697 # machine check (INT 0x12)
 698 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 699         .word 0            # offset 15:0
 700         .long SYS_CODE_SEL # selector 15:0
 701         .byte 0            # 0 for interrupt gate
 702         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 703         .word 0            # offset 31:16
 704
 705 # SIMD floating-point exception (INT 0x13)
 706 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 707         .word 0            # offset 15:0
 708         .long SYS_CODE_SEL # selector 15:0
 709         .byte 0            # 0 for interrupt gate
 710         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 711         .word 0            # offset 31:16
 712
 713 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 714     .fill 85 * 8, 1, 0   # db (85 * 8) dup(0)
 715
 716 # IRQ 0 (System timer) - (INT 0x68)
 717 .equ                IRQ0_SEL, .-IDT_BASE
 718         .word 0            # offset 15:0
 719         .long SYS_CODE_SEL # selector 15:0
 720         .byte 0            # 0 for interrupt gate
 721         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 722         .word 0            # offset 31:16
 723
 724 # IRQ 1 (8042 Keyboard controller) - (INT 0x69)
 725 .equ                IRQ1_SEL, .-IDT_BASE
 726         .word 0            # offset 15:0
 727         .long SYS_CODE_SEL # selector 15:0
 728         .byte 0            # 0 for interrupt gate
 729         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 730         .word 0            # offset 31:16
 731
 732 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 0x6a)
 733 .equ                IRQ2_SEL, .-IDT_BASE
 734         .word 0            # offset 15:0
 735         .long SYS_CODE_SEL # selector 15:0
 736         .byte 0            # 0 for interrupt gate
 737         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 738         .word 0            # offset 31:16
 739
 740 # IRQ 3 (COM 2) - (INT 0x6b)
 741 .equ                IRQ3_SEL, .-IDT_BASE
 742         .word 0            # offset 15:0
 743         .long SYS_CODE_SEL # selector 15:0
 744         .byte 0            # 0 for interrupt gate
 745         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 746         .word 0            # offset 31:16
 747
 748 # IRQ 4 (COM 1) - (INT 0x6c)
 749 .equ                IRQ4_SEL, .-IDT_BASE
 750         .word 0            # offset 15:0
 751         .long SYS_CODE_SEL # selector 15:0
 752         .byte 0            # 0 for interrupt gate
 753         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 754         .word 0            # offset 31:16
 755
 756 # IRQ 5 (LPT 2) - (INT 0x6d)
 757 .equ                IRQ5_SEL, .-IDT_BASE
 758         .word 0            # offset 15:0
 759         .long SYS_CODE_SEL # selector 15:0
 760         .byte 0            # 0 for interrupt gate
 761         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 762         .word 0            # offset 31:16
 763
 764 # IRQ 6 (Floppy controller) - (INT 0x6e)
 765 .equ                IRQ6_SEL, .-IDT_BASE
 766         .word 0            # offset 15:0
 767         .long SYS_CODE_SEL # selector 15:0
 768         .byte 0            # 0 for interrupt gate
 769         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 770         .word 0            # offset 31:16
 771
 772 # IRQ 7 (LPT 1) - (INT 0x6f)
 773 .equ                IRQ7_SEL, .-IDT_BASE
 774         .word 0            # offset 15:0
 775         .long SYS_CODE_SEL # selector 15:0
 776         .byte 0            # 0 for interrupt gate
 777         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 778         .word 0            # offset 31:16
 779
 780 # IRQ 8 (RTC Alarm) - (INT 0x70)
 781 .equ                IRQ8_SEL, .-IDT_BASE
 782         .word 0            # offset 15:0
 783         .long SYS_CODE_SEL # selector 15:0
 784         .byte 0            # 0 for interrupt gate
 785         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 786         .word 0            # offset 31:16
 787
 788 # IRQ 9 - (INT 0x71)
 789 .equ                IRQ9_SEL, .-IDT_BASE
 790         .word 0            # offset 15:0
 791         .long SYS_CODE_SEL # selector 15:0
 792         .byte 0            # 0 for interrupt gate
 793         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 794         .word 0            # offset 31:16
 795
 796 # IRQ 10 - (INT 0x72)
 797 .equ                 IRQ10_SEL, .-IDT_BASE
 798         .word 0            # offset 15:0
 799         .long SYS_CODE_SEL # selector 15:0
 800         .byte 0            # 0 for interrupt gate
 801         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 802         .word 0            # offset 31:16
 803
 804 # IRQ 11 - (INT 0x73)
 805 .equ                 IRQ11_SEL, .-IDT_BASE
 806         .word 0            # offset 15:0
 807         .long SYS_CODE_SEL # selector 15:0
 808         .byte 0            # 0 for interrupt gate
 809         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 810         .word 0            # offset 31:16
 811
 812 # IRQ 12 (PS/2 mouse) - (INT 0x74)
 813 .equ                 IRQ12_SEL, .-IDT_BASE
 814         .word 0            # offset 15:0
 815         .long SYS_CODE_SEL # selector 15:0
 816         .byte 0            # 0 for interrupt gate
 817         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 818         .word 0            # offset 31:16
 819
 820 # IRQ 13 (Floating point error) - (INT 0x75)
 821 .equ                 IRQ13_SEL, .-IDT_BASE
 822         .word 0            # offset 15:0
 823         .long SYS_CODE_SEL # selector 15:0
 824         .byte 0            # 0 for interrupt gate
 825         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 826         .word 0            # offset 31:16
 827
 828 # IRQ 14 (Secondary IDE) - (INT 0x76)
 829 .equ                 IRQ14_SEL, .-IDT_BASE
 830         .word 0            # offset 15:0
 831         .long SYS_CODE_SEL # selector 15:0
 832         .byte 0            # 0 for interrupt gate
 833         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 834         .word 0            # offset 31:16
 835
 836 # IRQ 15 (Primary IDE) - (INT 0x77)
 837 .equ                 IRQ15_SEL, .-IDT_BASE
 838         .word 0            # offset 15:0
 839         .long SYS_CODE_SEL # selector 15:0
 840         .byte 0            # 0 for interrupt gate
 841         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 842         .word 0            # offset 31:16
 843
 844 IDT_END:
 845
 846         .p2align 1
 847
 848 MemoryMapSize:  .long 0
 849 MemoryMap:  .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         .long 0,0,0,0,0,0,0,0
 873         .long 0,0,0,0,0,0,0,0
 874         .long 0,0,0,0,0,0,0,0
 875         .long 0,0,0,0,0,0,0,0
 876         .long 0,0,0,0,0,0,0,0
 877         .long 0,0,0,0,0,0,0,0
 878         .long 0,0,0,0,0,0,0,0
 879
 880         .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
 881         .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
 882
 883         .org 0x0fe0
 884 MyStack:
 885         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 886         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 887         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 888         #    8259.c
 889
 890         int $8
 891         iret
 892
 893         int $9
 894         iret
 895
 896         int $10
 897         iret
 898
 899         int $11
 900         iret
 901
 902         int $12
 903         iret
 904
 905         int $13
 906         iret
 907
 908         int $14
 909         iret
 910
 911         int $15
 912         iret
 913
 914
 915         .org 0x0ffe
 916 BlockSignature:
 917         .word 0xaa55
 918
 919