DuetPkg/BootSector/start16.S

   1 #------------------------------------------------------------------------------
   2 #*
   3 #*   Copyright 2006 - 2007, Intel Corporation
   4 #*   All rights reserved. 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 ASM_GLOBAL _start
  31 _start:
  32 Ia32Jump:
  33   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  34   nop
  35
  36 OemId:             .ascii  "INTEL   "    # OemId               - 8 bytes
  37
  38 SectorSize:        .word  0              # Sector Size         - 16 bits
  39 SectorsPerCluster: .byte  0              # Sector Per Cluster  - 8 bits
  40 ReservedSectors:   .word  0              # Reserved Sectors    - 16 bits
  41 NoFats:            .byte  0              # Number of FATs      - 8 bits
  42 RootEntries:       .word  0              # Root Entries        - 16 bits
  43 Sectors:           .word  0              # Number of Sectors   - 16 bits
  44 Media:             .byte  0              # Media               - 8 bits  - ignored
  45 SectorsPerFat:     .word  0              # Sectors Per FAT     - 16 bits
  46 SectorsPerTrack:   .word  0              # Sectors Per Track   - 16 bits - ignored
  47 Heads:             .word  0              # Heads               - 16 bits - ignored
  48 HiddenSectors:     .long  0              # Hidden Sectors      - 32 bits - ignored
  49 LargeSectors:      .long  0              # Large Sectors       - 32 bits
  50 PhysicalDrive:     .byte  0              # PhysicalDriveNumber - 8 bits  - ignored
  51 CurrentHead:       .byte  0              # Current Head        - 8 bits
  52 Signature:         .byte  0              # Signature           - 8 bits  - ignored
  53 VolId:             .ascii  "    "        # Volume Serial Number- 4 bytes
  54 FatLabel:          .ascii  "           " # Label               - 11 bytes
  55 SystemId:          .ascii  "FAT16   "    # SystemId            - 8 bytes
  56
  57 BootSectorEntryPoint:
  58         #ASSUME ds:@code
  59         #ASSUME ss:@code
  60       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  61       # cx = Start Cluster of EfiLdr
  62       # dx = Start Cluster of Efivar.bin
  63
  64 # Re use the BPB data stored in Boot Sector
  65         movw    $0x7c00, %bp
  66
  67         pushw   %cx
  68 # Read Efivar.bin
  69 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  70         movw    $0x1900, %ax
  71         movw    %ax, %es
  72         testw   %dx, %dx
  73         jnz     CheckVarStoreSize
  74
  75         movb    $1, %al
  76 NoVarStore:
  77         pushw   %es
  78 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  79         movb    %al, %es:4
  80         jmp     SaveVolumeId
  81
  82 CheckVarStoreSize:
  83         movw    %dx, %di
  84         cmpl    $0x4000, %ds:2(%di)
  85         movb    $2, %al
  86         jne     NoVarStore
  87
  88 LoadVarStore:
  89         movb    $0, %al
  90         movb    %al, %es:4
  91         movw    (%di), %cx
  92 #       ES:DI = 1500:0
  93         xorw    %di, %di
  94         pushw   %es
  95         movw    $0x1500, %ax
  96         movw    %ax, %es
  97         call    ReadFile
  98 SaveVolumeId:
  99         popw    %es
 100         movw    VolId(%bp), %ax
 101         movw    %ax, %es:0                      # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 102         movw    VolId+2(%bp), %ax
 103         movw    %ax, %es:2
 104
 105 # Read Efildr
 106         popw    %cx
 107 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 108 #       ES:DI = 2000:0, first cluster will be read again
 109         xorw    %di, %di                            # di = 0
 110         movw    $0x2000, %ax
 111         movw    %ax, %es
 112         call    ReadFile
 113         movw    %cs, %ax
 114         movw    %ax, %cs:JumpSegment
 115
 116 JumpFarInstruction:
 117         .byte   0xea
 118 JumpOffset:
 119         .word   0x200
 120 JumpSegment:
 121         .word   0x2000
 122
 123
 124
 125 # ****************************************************************************
 126 # ReadFile
 127 #
 128 # Arguments:
 129 #   CX    = Start Cluster of File
 130 #   ES:DI = Buffer to store file content read from disk
 131 #
 132 # Return:
 133 #   (ES << 4 + DI) = end of file content Buffer
 134 #
 135 # ****************************************************************************
 136 ReadFile:
 137 # si      = NumberOfClusters
 138 # cx      = ClusterNumber
 139 # dx      = CachedFatSectorNumber
 140 # ds:0000 = CacheFatSectorBuffer
 141 # es:di   = Buffer to load file
 142 # bx      = NextClusterNumber
 143         pusha
 144         movw    $1, %si                             # NumberOfClusters = 1
 145         pushw   %cx                                 # Push Start Cluster onto stack
 146         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 147 FatChainLoop:
 148         movw    %cx, %ax                            # ax = ClusterNumber
 149         andw    $0xfff8, %ax                        # ax = ax & 0xfff8
 150         cmpw    $0xfff8, %ax                        # See if this is the last cluster
 151         je      FoundLastCluster                    # Jump if last cluster found
 152         movw    %cx, %ax                            # ax = ClusterNumber
 153         shlw    %ax                                 # FatOffset = ClusterNumber * 2
 154         pushw   %si                                 # Save si
 155         movw    %ax, %si                            # si = FatOffset
 156         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 157         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 158         andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
 159         cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
 160         je      SkipFatRead
 161         movw    $2, %bx
 162         pushw   %es
 163         pushw   %ds
 164         popw    %es
 165         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 166         popw    %es
 167         movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
 168 SkipFatRead:
 169         movw    (%si), %bx                          # bx = NextClusterNumber
 170         movw    %cx, %ax                            # ax = ClusterNumber
 171         popw    %si                                 # Restore si
 172         decw    %bx                                 # bx = NextClusterNumber - 1
 173         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 174         jne     ReadClusters
 175         incw    %bx                                 # bx = NextClusterNumber
 176         incw    %si                                 # NumberOfClusters++
 177         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 178         jmp     FatChainLoop
 179 ReadClusters:
 180         incw    %bx
 181         popw    %ax                                 # ax = StartCluster
 182         pushw   %bx                                 # StartCluster = NextClusterNumber
 183         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 184         subw    $2, %ax                             # ax = StartCluster - 2
 185         xorb    %bh, %bh
 186         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 187         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 188         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 189         pushw   %ax                                 # save start sector
 190         movw    %si, %ax                            # ax = NumberOfClusters
 191         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 192         movw    %ax, %bx                            # bx = Number of Sectors
 193         popw    %ax                                 # ax = Start Sector
 194         call    ReadBlocks
 195         movw    $1, %si                             # NumberOfClusters = 1
 196         jmp     FatChainLoop
 197 FoundLastCluster:
 198         popw    %cx
 199         popa
 200         ret
 201
 202
 203 # ****************************************************************************
 204 # ReadBlocks - Reads a set of blocks from a block device
 205 #
 206 # AX    = Start LBA
 207 # BX    = Number of Blocks to Read
 208 # ES:DI = Buffer to store sectors read from disk
 209 # ****************************************************************************
 210
 211 # cx = Blocks
 212 # bx = NumberOfBlocks
 213 # si = StartLBA
 214
 215 ReadBlocks:
 216         pusha
 217         addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
 218         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 219         movl    %eax, %esi                          # esi = Start LBA
 220         movw    %bx, %cx                            # cx = Number of blocks to read
 221 ReadCylinderLoop:
 222         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 223         movl    %esi, %eax                          # eax = Start LBA
 224         xorl    %edx, %edx                          # edx = 0
 225         movzwl  (%bp), %ebx                         # bx = MaxSector
 226         divl    %ebx                                # ax = StartLBA / MaxSector
 227         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 228
 229         movw    (%bp), %bx                          # bx = MaxSector
 230         subw    %dx, %bx                            # bx = MaxSector - Sector
 231         incw    %bx                                 # bx = MaxSector - Sector + 1
 232         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 233         jg      LimitTransfer
 234         movw    %cx, %bx                            # bx = Blocks
 235 LimitTransfer:
 236         pushw   %ax                                 # save ax
 237         movw    %es, %ax                            # ax = es
 238         shrw    $(BLOCK_SHIFT-4), %ax               # ax = Number of blocks into mem system
 239         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 240         addw    %bx, %ax                            # ax = End Block number of transfer
 241         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 242         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 243         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 244         subw    %ax, %bx                            # Decrease transfer size by block overage
 245 NotCrossing64KBoundry:
 246         popw    %ax                                 # restore ax
 247
 248         pushw   %cx
 249         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 250         xorw    %dx, %dx                            # dx = 0
 251         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 252                                                     # dx = ax % (MaxHead + 1) = Head
 253
 254         pushw   %bx                                 # Save number of blocks to transfer
 255         movb    %dl, %dh                            # dh = Head
 256         movw    $0x7c00, %bp                        # bp = 0x7c00
 257         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 258         movb    %al, %ch                            # ch = Cylinder
 259         movb    %bl, %al                            # al = Blocks
 260         movb    $2, %ah                             # ah = Function 2
 261         movw    %di, %bx                            # es:bx = Buffer address
 262         int     $0x13
 263         jc      DiskError
 264         popw    %bx
 265         popw    %cx
 266         movzwl  %bx, %ebx
 267         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 268         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 269         movw    %es, %ax
 270         shlw    $(BLOCK_SHIFT-4), %bx
 271         addw    %bx, %ax
 272         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 273         cmpw    $0, %cx
 274         jne     ReadCylinderLoop
 275         popa
 276         ret
 277
 278 DiskError:
 279         pushw %cs
 280         popw %ds
 281         leaw ErrorString, %si
 282         movw $7, %cx
 283         jmp  PrintStringAndHalt
 284
 285 PrintStringAndHalt:
 286         movw $0xb800, %ax
 287         movw %ax, %es
 288         movw $160, %di
 289         rep
 290         movsw
 291 Halt:
 292         jmp   Halt
 293
 294 ErrorString:
 295         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
 296
 297         # .org     0x01fa # Just for passing build.
 298 LBAOffsetForBootSector:
 299         .long   0x0
 300
 301         # .org     0x01fe # Just for passing build.
 302         .word   0xaa55
 303
 304 #******************************************************************************
 305 #******************************************************************************
 306 #******************************************************************************
 307
 308 .equ                 DELAY_PORT,            0x0ed     # Port to use for 1uS delay
 309 .equ                 KBD_CONTROL_PORT,      0x060     # 8042 control port
 310 .equ                 KBD_STATUS_PORT,       0x064     # 8042 status port
 311 .equ                 WRITE_DATA_PORT_CMD,   0x0d1     # 8042 command to write the data port
 312 .equ                 ENABLE_A20_CMD,        0x0df     # 8042 command to enable A20
 313
 314         # .org     0x0200 # Just for passing build.
 315         jmp start
 316 Em64String:
 317         .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
 318
 319 start:
 320         movw %cs, %ax
 321         movw %ax, %ds
 322         movw %ax, %es
 323         movw %ax, %ss
 324         movw $MyStack, %sp
 325
 326 #        mov ax,0b800h
 327 #        mov es,ax
 328 #        mov byte ptr es:[160],'a'
 329 #        mov ax,cs
 330 #        mov es,ax
 331
 332         movl $0, %ebx
 333         leal MemoryMap, %edi
 334 MemMapLoop:
 335         movl $0xe820, %eax
 336         movl $20, %ecx
 337         movl $0x534d4150, %edx  # 0x534d4150  stands for 'SMAP'
 338         int $0x15
 339         jc  MemMapDone
 340         addl $20, %edi
 341         cmpl $0, %ebx
 342         je  MemMapDone
 343         jmp MemMapLoop
 344 MemMapDone:
 345         leal MemoryMap, %eax
 346         subl %eax, %edi                     # Get the address of the memory map
 347         movl %edi, MemoryMapSize            # Save the size of the memory map
 348
 349         xorl    %ebx, %ebx
 350         movw    %cs, %bx                    # BX=segment
 351         shll    $4, %ebx                    # BX="linear" address of segment base
 352         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 353         movl    %eax, gdtr + 2              # Put address of gdt into the gdtr
 354         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 355         movl    %eax, idtr + 2              # Put address of idt into the idtr
 356         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 357
 358         addl $0x1000, %ebx                  # Source of EFI32
 359         movl %ebx, JUMP+2
 360         addl $0x1000, %ebx
 361         movl %ebx, %esi                     # Source of EFILDR32
 362
 363 #        mov ax,0b800h
 364 #        mov es,ax
 365 #        mov byte ptr es:[162],'b'
 366 #        mov ax,cs
 367 #        mov es,ax
 368
 369 #
 370 # Enable A20 Gate
 371 #
 372
 373         movw $0x2401, %ax                   # Enable A20 Gate
 374         int $0x15
 375         jnc A20GateEnabled                  # Jump if it suceeded
 376
 377 #
 378 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 379 #
 380
 381         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 382         jnz     Timeout8042                 # Jump if the 8042 timed out
 383         outw    %ax, $DELAY_PORT            # Delay 1 uS
 384         movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 385         outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
 386         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 387         jnz     Timeout8042                 # Jump if the 8042 timed out
 388         movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
 389         outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 390         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 391         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 392 Delay25uS:
 393         outw    %ax, $DELAY_PORT            # Delay 1 uS
 394         loop    Delay25uS
 395 Timeout8042:
 396
 397
 398 A20GateEnabled:
 399
 400 #
 401 # DISABLE INTERRUPTS - Entering Protected Mode
 402 #
 403
 404         cli
 405
 406 #        mov ax,0b800h
 407 #        mov es,ax
 408 #        mov byte ptr es:[164],'c'
 409 #        mov ax,cs
 410 #        mov es,ax
 411
 412         .byte   0x66
 413         lgdt    gdtr
 414         .byte   0x66
 415         lidt    idtr
 416
 417         movl    %cr0, %eax
 418         orb     $1, %al
 419         movl    %eax, %cr0
 420
 421         movl $0x008, %eax                   # Flat data descriptor
 422         movl $0x00400000, %ebp              # Destination of EFILDR32
 423         movl $0x00070000, %ebx              # Length of copy
 424
 425 JUMP:
 426 # jmp far 0010:00020000
 427         .byte 0x66
 428         .byte 0xea
 429         .long 0x00020000
 430         .word 0x0010
 431
 432 Empty8042InputBuffer:
 433         movw $0, %cx
 434 Empty8042Loop:
 435         outw    %ax, $DELAY_PORT            # Delay 1us
 436         inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 437         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 438         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 439         ret
 440
 441 ##############################################################################
 442 # data
 443 ##############################################################################
 444
 445         .align 0x2
 446
 447 gdtr:   .word  GDT_END - GDT_BASE - 1       # GDT limit
 448         .long 0                             # (GDT base gets set above)
 449 ##############################################################################
 450 #   global descriptor table (GDT)
 451 ##############################################################################
 452
 453         .align 0x2
 454
 455 ASM_GLOBAL GDT_BASE
 456 GDT_BASE:
 457 # null descriptor
 458 .equ                NULL_SEL, .-GDT_BASE
 459         .word 0         # limit 15:0
 460         .word 0         # base 15:0
 461         .byte 0         # base 23:16
 462         .byte 0         # type
 463         .byte 0         # limit 19:16, flags
 464         .byte 0         # base 31:24
 465
 466 # linear data segment descriptor
 467 .equ            LINEAR_SEL, .-GDT_BASE
 468         .word 0xFFFF    # limit 0xFFFFF
 469         .word 0         # base 0
 470         .byte 0
 471         .byte 0x92      # present, ring 0, data, expand-up, writable
 472         .byte 0xCF              # page-granular, 32-bit
 473         .byte 0
 474
 475 # linear code segment descriptor
 476 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 477         .word 0xFFFF    # limit 0xFFFFF
 478         .word 0         # base 0
 479         .byte 0
 480         .byte 0x9A      # present, ring 0, data, expand-up, writable
 481         .byte 0xCF              # page-granular, 32-bit
 482         .byte 0
 483
 484 # system data segment descriptor
 485 .equ            SYS_DATA_SEL, .-GDT_BASE
 486         .word 0xFFFF    # limit 0xFFFFF
 487         .word 0         # base 0
 488         .byte 0
 489         .byte 0x92      # present, ring 0, data, expand-up, writable
 490         .byte 0xCF              # page-granular, 32-bit
 491         .byte 0
 492
 493 # system code segment descriptor
 494 .equ            SYS_CODE_SEL, .-GDT_BASE
 495         .word 0xFFFF    # limit 0xFFFFF
 496         .word 0         # base 0
 497         .byte 0
 498         .byte 0x9A      # present, ring 0, data, expand-up, writable
 499         .byte 0xCF              # page-granular, 32-bit
 500         .byte 0
 501
 502 # spare segment descriptor
 503 .equ        SPARE3_SEL, .-GDT_BASE
 504         .word 0         # limit 0xFFFFF
 505         .word 0         # base 0
 506         .byte 0
 507         .byte 0         # present, ring 0, data, expand-up, writable
 508         .byte 0         # page-granular, 32-bit
 509         .byte 0
 510
 511 # spare segment descriptor
 512 .equ        SPARE4_SEL, .-GDT_BASE
 513         .word 0         # limit 0xFFFFF
 514         .word 0         # base 0
 515         .byte 0
 516         .byte 0         # present, ring 0, data, expand-up, writable
 517         .byte 0         # page-granular, 32-bit
 518         .byte 0
 519
 520 # spare segment descriptor
 521 .equ        SPARE5_SEL, .-GDT_BASE
 522         .word 0         # limit 0xFFFFF
 523         .word 0         # base 0
 524         .byte 0
 525         .byte 0         # present, ring 0, data, expand-up, writable
 526         .byte 0         # page-granular, 32-bit
 527         .byte 0
 528
 529 GDT_END:
 530
 531         .align 0x2
 532
 533
 534
 535 idtr:   .word IDT_END - IDT_BASE - 1  # IDT limit
 536         .long 0                       # (IDT base gets set above)
 537 ##############################################################################
 538 #   interrupt descriptor table (IDT)
 539 #
 540 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 541 #       mappings.  This implementation only uses the system timer and all other
 542 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 543 #       for convenience.
 544 ##############################################################################
 545
 546 #idt_tag db "IDT",0
 547         .align 0x2
 548
 549 ASM_GLOBAL IDT_BASE
 550 IDT_BASE:
 551 # divide by zero (INT 0)
 552 .equ                DIV_ZERO_SEL, .-IDT_BASE
 553         .word 0             # offset 15:0
 554         .word SYS_CODE_SEL  # selector 15:0
 555         .byte 0             # 0 for interrupt gate
 556         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 557         .word 0             # offset 31:16
 558
 559 # debug exception (INT 1)
 560 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 561         .word 0             # offset 15:0
 562         .word SYS_CODE_SEL  # selector 15:0
 563         .byte 0             # 0 for interrupt gate
 564         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 565         .word 0             # offset 31:16
 566
 567 # NMI (INT 2)
 568 .equ                NMI_SEL, .-IDT_BASE
 569         .word 0             # offset 15:0
 570         .word SYS_CODE_SEL  # selector 15:0
 571         .byte 0             # 0 for interrupt gate
 572         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 573         .word 0             # offset 31:16
 574
 575 # soft breakpoint (INT 3)
 576 .equ                BREAKPOINT_SEL, .-IDT_BASE
 577         .word 0             # offset 15:0
 578         .word SYS_CODE_SEL  # selector 15:0
 579         .byte 0             # 0 for interrupt gate
 580         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 581         .word 0             # offset 31:16
 582
 583 # overflow (INT 4)
 584 .equ                OVERFLOW_SEL, .-IDT_BASE
 585         .word 0             # offset 15:0
 586         .word SYS_CODE_SEL  # selector 15:0
 587         .byte 0             # 0 for interrupt gate
 588         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 589         .word 0             # offset 31:16
 590
 591 # bounds check (INT 5)
 592 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 593         .word 0             # offset 15:0
 594         .word SYS_CODE_SEL  # selector 15:0
 595         .byte 0             # 0 for interrupt gate
 596         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 597         .word 0             # offset 31:16
 598
 599 # invalid opcode (INT 6)
 600 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 601         .word 0             # offset 15:0
 602         .word SYS_CODE_SEL  # selector 15:0
 603         .byte 0             # 0 for interrupt gate
 604         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 605         .word 0             # offset 31:16
 606
 607 # device not available (INT 7)
 608 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 609         .word 0             # offset 15:0
 610         .word SYS_CODE_SEL  # selector 15:0
 611         .byte 0             # 0 for interrupt gate
 612         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 613         .word 0             # offset 31:16
 614
 615 # double fault (INT 8)
 616 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 617         .word 0             # offset 15:0
 618         .word SYS_CODE_SEL  # selector 15:0
 619         .byte 0             # 0 for interrupt gate
 620         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 621         .word 0             # offset 31:16
 622
 623 # Coprocessor segment overrun - reserved (INT 9)
 624 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 625         .word 0             # offset 15:0
 626         .word SYS_CODE_SEL  # selector 15:0
 627         .byte 0             # 0 for interrupt gate
 628         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 629         .word 0             # offset 31:16
 630
 631 # invalid TSS (INT 0ah)
 632 .equ                INVALID_TSS_SEL, .-IDT_BASE
 633         .word 0             # offset 15:0
 634         .word SYS_CODE_SEL  # selector 15:0
 635         .byte 0             # 0 for interrupt gate
 636         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 637         .word 0             # offset 31:16
 638
 639 # segment not present (INT 0bh)
 640 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 641         .word 0             # offset 15:0
 642         .word SYS_CODE_SEL  # selector 15:0
 643         .byte 0             # 0 for interrupt gate
 644         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 645         .word 0             # offset 31:16
 646
 647 # stack fault (INT 0ch)
 648 .equ                STACK_FAULT_SEL, .-IDT_BASE
 649         .word 0             # offset 15:0
 650         .word SYS_CODE_SEL  # selector 15:0
 651         .byte 0             # 0 for interrupt gate
 652         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 653         .word 0             # offset 31:16
 654
 655 # general protection (INT 0dh)
 656 .equ                GP_FAULT_SEL, .-IDT_BASE
 657         .word 0             # offset 15:0
 658         .word SYS_CODE_SEL  # selector 15:0
 659         .byte 0             # 0 for interrupt gate
 660         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 661         .word 0             # offset 31:16
 662
 663 # page fault (INT 0eh)
 664 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 665         .word 0             # offset 15:0
 666         .word SYS_CODE_SEL  # selector 15:0
 667         .byte 0             # 0 for interrupt gate
 668         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 669         .word 0             # offset 31:16
 670
 671 # Intel reserved - do not use (INT 0fh)
 672 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 673         .word 0             # offset 15:0
 674         .word SYS_CODE_SEL  # selector 15:0
 675         .byte 0             # 0 for interrupt gate
 676         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 677         .word 0             # offset 31:16
 678
 679 # floating point error (INT 10h)
 680 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 681         .word 0             # offset 15:0
 682         .word SYS_CODE_SEL  # selector 15:0
 683         .byte 0             # 0 for interrupt gate
 684         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 685         .word 0             # offset 31:16
 686
 687 # alignment check (INT 11h)
 688 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 689         .word 0             # offset 15:0
 690         .word SYS_CODE_SEL  # selector 15:0
 691         .byte 0             # 0 for interrupt gate
 692         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 693         .word 0             # offset 31:16
 694
 695 # machine check (INT 12h)
 696 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 697         .word 0             # offset 15:0
 698         .word SYS_CODE_SEL  # selector 15:0
 699         .byte 0             # 0 for interrupt gate
 700         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 701         .word 0             # offset 31:16
 702
 703 # SIMD floating-point exception (INT 13h)
 704 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 705         .word 0             # offset 15:0
 706         .word SYS_CODE_SEL  # selector 15:0
 707         .byte 0             # 0 for interrupt gate
 708         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 709         .word 0             # offset 31:16
 710
 711 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 712         .fill  85 * 8, 1, 0
 713
 714 # IRQ 0 (System timer) - (INT 68h)
 715 .equ                IRQ0_SEL, .-IDT_BASE
 716         .word 0             # offset 15:0
 717         .word SYS_CODE_SEL  # selector 15:0
 718         .byte 0             # 0 for interrupt gate
 719         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 720         .word 0             # offset 31:16
 721
 722 # IRQ 1 (8042 Keyboard controller) - (INT 69h)
 723 .equ                IRQ1_SEL, .-IDT_BASE
 724         .word 0             # offset 15:0
 725         .word SYS_CODE_SEL  # selector 15:0
 726         .byte 0             # 0 for interrupt gate
 727         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 728         .word 0             # offset 31:16
 729
 730 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
 731 .equ                IRQ2_SEL, .-IDT_BASE
 732         .word 0             # offset 15:0
 733         .word SYS_CODE_SEL  # selector 15:0
 734         .byte 0             # 0 for interrupt gate
 735         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 736         .word 0             # offset 31:16
 737
 738 # IRQ 3 (COM 2) - (INT 6bh)
 739 .equ                IRQ3_SEL, .-IDT_BASE
 740         .word 0             # offset 15:0
 741         .word SYS_CODE_SEL  # selector 15:0
 742         .byte 0             # 0 for interrupt gate
 743         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 744         .word 0             # offset 31:16
 745
 746 # IRQ 4 (COM 1) - (INT 6ch)
 747 .equ                IRQ4_SEL, .-IDT_BASE
 748         .word 0             # offset 15:0
 749         .word SYS_CODE_SEL  # selector 15:0
 750         .byte 0             # 0 for interrupt gate
 751         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 752         .word 0             # offset 31:16
 753
 754 # IRQ 5 (LPT 2) - (INT 6dh)
 755 .equ                IRQ5_SEL, .-IDT_BASE
 756         .word 0             # offset 15:0
 757         .word SYS_CODE_SEL  # selector 15:0
 758         .byte 0             # 0 for interrupt gate
 759         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 760         .word 0             # offset 31:16
 761
 762 # IRQ 6 (Floppy controller) - (INT 6eh)
 763 .equ                IRQ6_SEL, .-IDT_BASE
 764         .word 0             # offset 15:0
 765         .word SYS_CODE_SEL  # selector 15:0
 766         .byte 0             # 0 for interrupt gate
 767         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 768         .word 0             # offset 31:16
 769
 770 # IRQ 7 (LPT 1) - (INT 6fh)
 771 .equ                IRQ7_SEL, .-IDT_BASE
 772         .word 0             # offset 15:0
 773         .word SYS_CODE_SEL  # selector 15:0
 774         .byte 0             # 0 for interrupt gate
 775         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 776         .word 0             # offset 31:16
 777
 778 # IRQ 8 (RTC Alarm) - (INT 70h)
 779 .equ                IRQ8_SEL, .-IDT_BASE
 780         .word 0             # offset 15:0
 781         .word SYS_CODE_SEL  # selector 15:0
 782         .byte 0             # 0 for interrupt gate
 783         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 784         .word 0             # offset 31:16
 785
 786 # IRQ 9 - (INT 71h)
 787 .equ                IRQ9_SEL, .-IDT_BASE
 788         .word 0             # offset 15:0
 789         .word SYS_CODE_SEL  # selector 15:0
 790         .byte 0             # 0 for interrupt gate
 791         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 792         .word 0             # offset 31:16
 793
 794 # IRQ 10 - (INT 72h)
 795 .equ                 IRQ10_SEL, .-IDT_BASE
 796         .word 0             # offset 15:0
 797         .word SYS_CODE_SEL  # selector 15:0
 798         .byte 0             # 0 for interrupt gate
 799         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 800         .word 0             # offset 31:16
 801
 802 # IRQ 11 - (INT 73h)
 803 .equ                 IRQ11_SEL, .-IDT_BASE
 804         .word 0             # offset 15:0
 805         .word SYS_CODE_SEL  # selector 15:0
 806         .byte 0             # 0 for interrupt gate
 807         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 808         .word 0             # offset 31:16
 809
 810 # IRQ 12 (PS/2 mouse) - (INT 74h)
 811 .equ                 IRQ12_SEL, .-IDT_BASE
 812         .word 0             # offset 15:0
 813         .word SYS_CODE_SEL  # selector 15:0
 814         .byte 0             # 0 for interrupt gate
 815         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 816         .word 0             # offset 31:16
 817
 818 # IRQ 13 (Floating point error) - (INT 75h)
 819 .equ                 IRQ13_SEL, .-IDT_BASE
 820         .word 0             # offset 15:0
 821         .word SYS_CODE_SEL  # selector 15:0
 822         .byte 0             # 0 for interrupt gate
 823         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 824         .word 0             # offset 31:16
 825
 826 # IRQ 14 (Secondary IDE) - (INT 76h)
 827 .equ                 IRQ14_SEL, .-IDT_BASE
 828         .word 0             # offset 15:0
 829         .word SYS_CODE_SEL  # selector 15:0
 830         .byte 0             # 0 for interrupt gate
 831         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 832         .word 0             # offset 31:16
 833
 834 # IRQ 15 (Primary IDE) - (INT 77h)
 835 .equ                 IRQ15_SEL, .-IDT_BASE
 836         .word 0             # offset 15:0
 837         .word SYS_CODE_SEL  # selector 15:0
 838         .byte 0             # 0 for interrupt gate
 839         .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
 840         .word 0             # offset 31:16
 841
 842 IDT_END:
 843
 844         .align 0x2
 845
 846 MemoryMapSize:  .long 0
 847 MemoryMap:  .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         .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
 878         .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
 879         .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
 880
 881         .org 0x0fe0
 882 MyStack:
 883         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 884         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 885         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 886         #    8259.c
 887
 888         int $8
 889         iret
 890
 891         int $9
 892         iret
 893
 894         int $10
 895         iret
 896
 897         int $11
 898         iret
 899
 900         int $12
 901         iret
 902
 903         int $13
 904         iret
 905
 906         int $14
 907         iret
 908
 909         int $15
 910         iret
 911
 912
 913         .org 0x0ffe
 914 BlockSignature:
 915         .word 0xaa55