DuetPkg/BootSector/start.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 #*    start.S
  13 #*
  14 #*   Abstract:
  15 #*
  16 #------------------------------------------------------------------------------
  17
  18
  19
  20
  21
  22
  23 .equ                        FAT_DIRECTORY_ENTRY_SIZE, 0x020
  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 0x0
  30 Ia32Jump:
  31   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  32   nop
  33
  34 OemId:              .ascii   "INTEL   "       # OemId               - 8 bytes
  35
  36 SectorSize:         .word  0                  # Sector Size         - 16 bits
  37 SectorsPerCluster:  .byte  0                  # Sector Per Cluster  - 8 bits
  38 ReservedSectors:    .word  0                  # Reserved Sectors    - 16 bits
  39 NoFats:             .byte  0                  # Number of FATs      - 8 bits
  40 RootEntries:        .word  0                  # Root Entries        - 16 bits
  41 Sectors:            .word  0                  # Number of Sectors   - 16 bits
  42 Media:              .byte  0                  # Media               - 8 bits  - ignored
  43 SectorsPerFat:      .word  0                  # Sectors Per FAT     - 16 bits
  44 SectorsPerTrack:    .word  0                  # Sectors Per Track   - 16 bits - ignored
  45 Heads:              .word  0                  # Heads               - 16 bits - ignored
  46 HiddenSectors:      .long  0                  # Hidden Sectors      - 32 bits - ignored
  47 LargeSectors:       .long  0                  # Large Sectors       - 32 bits
  48 PhysicalDrive:      .byte  0                  # PhysicalDriveNumber - 8 bits  - ignored
  49 CurrentHead:        .byte  0                  # Current Head        - 8 bits
  50 Signature:          .byte  0                  # Signature           - 8 bits  - ignored
  51 VolId:              .ascii "    "             # Volume Serial Number- 4 bytes
  52 FatLabel:           .ascii "           "      # Label               - 11 bytes
  53 SystemId:           .ascii "FAT12   "         # SystemId            - 8 bytes
  54
  55 BootSectorEntryPoint:
  56         #ASSUME ds:@code
  57         #ASSUME ss:@code
  58       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  59       # cx = Start Cluster of EfiLdr
  60       # dx = Start Cluster of Efivar.bin
  61
  62 # Re use the BPB data stored in Boot Sector
  63         movw    $0x7c00, %bp
  64
  65         pushw   %cx
  66 # Read Efivar.bin
  67 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  68         movw    $0x1900, %ax
  69         movw    %ax, %es
  70         testw   %dx, %dx
  71         jnz     CheckVarStoreSize
  72
  73         movb    $1, %al
  74 NoVarStore:
  75         pushw   %es
  76 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  77         movb    %al, %es:4
  78         jmp     SaveVolumeId
  79
  80 CheckVarStoreSize:
  81         movw    %dx, %di
  82         cmpl    $0x4000, %ds:2(%di)
  83         movb    $2, %al
  84         jne     NoVarStore
  85
  86 LoadVarStore:
  87         movb    $0, %al
  88         movb    %al, %es:4
  89         movw    (%di), %cx
  90 #       ES:DI = 1500:0
  91         xorw    %di, %di
  92         pushw   %es
  93         movw    $0x1500, %ax
  94         movw    %ax, %es
  95         call    ReadFile
  96 SaveVolumeId:
  97         popw    %es
  98         movw    VolId(%bp), %ax
  99         movw    %ax, %es:0                     # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 100         movw    VolId+2(%bp), %ax
 101         movw    %ax, %es:2
 102
 103 # Read Efildr
 104         popw    %cx
 105 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 106 #       ES:DI = 2000:0, first cluster will be read again
 107         xorw    %di, %di                            # di = 0
 108         movw    $0x2000, %ax
 109         movw    %ax, %es
 110         call    ReadFile
 111         movw    %cs, %ax
 112         movw    %ax, %cs:JumpSegment
 113
 114 JumpFarInstruction:
 115         .byte   0xea
 116 JumpOffset:
 117         .word   0x200
 118 JumpSegment:
 119         .word   0x2000
 120
 121
 122
 123 # ****************************************************************************
 124 # ReadFile
 125 #
 126 # Arguments:
 127 #   CX    = Start Cluster of File
 128 #   ES:DI = Buffer to store file content read from disk
 129 #
 130 # Return:
 131 #   (ES << 4 + DI) = end of file content Buffer
 132 #
 133 # ****************************************************************************
 134 ReadFile:
 135 # si      = NumberOfClusters
 136 # cx      = ClusterNumber
 137 # dx      = CachedFatSectorNumber
 138 # ds:0000 = CacheFatSectorBuffer
 139 # es:di   = Buffer to load file
 140 # bx      = NextClusterNumber
 141         pusha
 142         movw    $1, %si                             # NumberOfClusters = 1
 143         pushw   %cx                                 # Push Start Cluster onto stack
 144         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 145 FatChainLoop:
 146         movw    %cx, %ax                            # ax = ClusterNumber
 147         andw    $0xff8, %ax                         # ax = ax & 0xff8
 148         cmpw    $0xff8, %ax                         # See if this is the last cluster
 149         je      FoundLastCluster                    # Jump if last cluster found
 150         movw    %cx, %ax                            # ax = ClusterNumber
 151         shlw    %ax                                 # ax = ClusterNumber * 2
 152         addw    %cx, %ax                            # ax = ClusterNumber * 2 + ClusterNumber = ClusterNumber * 3
 153         shrw    %ax                                 # FatOffset = ClusterNumber*3 / 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         andw    $1, %ax                             # See if this is an odd cluster number
 172         je      EvenFatEntry
 173         shrw    $4, %bx                             # NextClusterNumber = NextClusterNumber >> 4
 174 EvenFatEntry:
 175         andw    $0xfff, %bx                         # Strip upper 4 bits of NextClusterNumber
 176         popw    %si                                 # Restore si
 177         decw    %bx                                 # bx = NextClusterNumber - 1
 178         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 179         jne     ReadClusters
 180         incw    %bx                                 # bx = NextClusterNumber
 181         incw    %si                                 # NumberOfClusters++
 182         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 183         jmp     FatChainLoop
 184 ReadClusters:
 185         incw    %bx
 186         popw    %ax                                 # ax = StartCluster
 187         pushw   %bx                                 # StartCluster = NextClusterNumber
 188         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 189         subw    $2, %ax                             # ax = StartCluster - 2
 190         xorb    %bh, %bh
 191         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 192         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 193         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 194         pushw   %ax                                 # save start sector
 195         movw    %si, %ax                            # ax = NumberOfClusters
 196         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 197         movw    %ax, %bx                            # bx = Number of Sectors
 198         popw    %ax                                 # ax = Start Sector
 199         call    ReadBlocks
 200         movw    $1, %si                             # NumberOfClusters = 1
 201         jmp     FatChainLoop
 202 FoundLastCluster:
 203         popw    %cx
 204         popa
 205         ret
 206
 207
 208 # ****************************************************************************
 209 # ReadBlocks - Reads a set of blocks from a block device
 210 #
 211 # AX    = Start LBA
 212 # BX    = Number of Blocks to Read
 213 # ES:DI = Buffer to store sectors read from disk
 214 # ****************************************************************************
 215
 216 # cx = Blocks
 217 # bx = NumberOfBlocks
 218 # si = StartLBA
 219
 220 ReadBlocks:
 221         pusha
 222         addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
 223         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 224         movl    %eax, %esi                          # esi = Start LBA
 225         movw    %bx, %cx                            # cx = Number of blocks to read
 226 ReadCylinderLoop:
 227         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 228         movl    %esi, %eax                          # eax = Start LBA
 229         xorl    %edx, %edx                          # edx = 0
 230         movzwl  (%bp), %ebx                         # bx = MaxSector
 231         divl    %ebx                                # ax = StartLBA / MaxSector
 232         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 233
 234         movw    (%bp), %bx                          # bx = MaxSector
 235         subw    %dx, %bx                            # bx = MaxSector - Sector
 236         incw    %bx                                 # bx = MaxSector - Sector + 1
 237         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 238         jg      LimitTransfer
 239         movw    %cx, %bx                            # bx = Blocks
 240 LimitTransfer:
 241         pushw   %ax                                 # save ax
 242         movw    %es, %ax                            # ax = es
 243         shrw    %ax                                 # ax = Number of blocks into mem system
 244         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 245         addw    %bx, %ax                            # ax = End Block number of transfer
 246         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 247         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 248         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 249         subw    %ax, %bx                            # Decrease transfer size by block overage
 250 NotCrossing64KBoundry:
 251         popw    %ax                                 # restore ax
 252
 253         pushw   %cx
 254         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 255         xorw    %dx, %dx                            # dx = 0
 256         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 257                                                     # dx = ax % (MaxHead + 1) = Head
 258
 259         pushw   %bx                                 # Save number of blocks to transfer
 260         movb    %dl, %dh                            # dh = Head
 261         movw    $0x7c00, %bp                        # bp = 0x7c00
 262         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 263         movb    %al, %ch                            # ch = Cylinder
 264         movb    %bl, %al                            # al = Blocks
 265         movb    $2, %ah                             # ah = Function 2
 266         movw    %di, %bx                            # es:bx = Buffer address
 267         int     $0x13
 268         jc      DiskError
 269         popw    %bx
 270         popw    %cx
 271         movzwl  %bx, %ebx
 272         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 273         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 274         movw    %es, %ax
 275         shlw    %bx
 276         addw    %bx, %ax
 277         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 278         cmpw    $0, %cx
 279         jne     ReadCylinderLoop
 280         popa
 281         ret
 282
 283 DiskError:
 284         pushw %cs
 285         popw %ds
 286         leaw ErrorString, %si
 287         movw $7, %cx
 288         jmp  PrintStringAndHalt
 289
 290 PrintStringAndHalt:
 291         movw $0xb800, %ax
 292         movw %ax, %es
 293         movw $160, %di
 294         rep
 295         movsw
 296 Halt:
 297         jmp   Halt
 298
 299 ErrorString:
 300         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!',0x0c
 301
 302         .org     0x0241 # For Code size overflow, Modified this just for pass build
 303 LBAOffsetForBootSector:
 304         .long   0x0
 305
 306         #.org    0x0227  # For Code size overflow, Modified this just for pass build
 307         .word   0xaa55
 308
 309 #******************************************************************************
 310 #******************************************************************************
 311 #******************************************************************************
 312
 313 .equ                 DELAY_PORT, 0x0ed           # Port to use for 1uS delay
 314 .equ                 KBD_CONTROL_PORT, 0x060     # 8042 control port
 315 .equ                 KBD_STATUS_PORT, 0x064      # 8042 status port
 316 .equ                 WRITE_DATA_PORT_CMD, 0x0d1  # 8042 command to write the data port
 317 .equ                 ENABLE_A20_CMD, 0x0df       # 8042 command to enable A20
 318
 319         #.org     0x200
 320         jmp start
 321 Em64String:
 322         .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
 323
 324 start:
 325         movw %cs, %ax
 326         movw %ax, %ds
 327         movw %ax, %es
 328         movw %ax, %ss
 329         movw $MyStack, %sp
 330
 331 #        mov ax,0b800h
 332 #        mov es,ax
 333 #        mov byte ptr es:[160],'a'
 334 #        mov ax,cs
 335 #        mov es,ax
 336
 337         movl $0, %ebx
 338         leal MemoryMap, %edi
 339 MemMapLoop:
 340         movl $0xe820, %eax
 341         movl $20, %ecx
 342         movl $0x534d4150, %edx  # SMAP
 343         int $0x15
 344         jc  MemMapDone
 345         addl $20, %edi
 346         cmpl $0, %ebx
 347         je  MemMapDone
 348         jmp MemMapLoop
 349 MemMapDone:
 350         leal MemoryMap, %eax
 351         subl %eax, %edi                     # Get the address of the memory map
 352         movl %edi, MemoryMapSize            # Save the size of the memory map
 353
 354         xorl    %ebx, %ebx
 355         movw    %cs, %bx                    # BX=segment
 356         shll    $4, %ebx                    # BX="linear" address of segment base
 357         leal    GDT_BASE(%ebx), %eax        #
 358         movl    %eax, (gdtr + 2)            #
 359         leal    IDT_BASE(%ebx), %eax        #
 360         movl    %eax, (idtr + 2)            #
 361         leal    MemoryMapSize(%ebx), %edx   #
 362
 363         addl $0x1000, %ebx                  # Source of EFI32
 364         movl %ebx, JUMP+2
 365         addl $0x1000, %ebx
 366         movl %ebx, %esi                     # Source of EFILDR32
 367
 368 #        mov ax,0b800h
 369 #        mov es,ax
 370 #        mov byte ptr es:[162],'b'
 371 #        mov ax,cs
 372 #        mov es,ax
 373
 374 #
 375 # Enable A20 Gate
 376 #
 377
 378         movw $0x2401, %ax                   # Enable A20 Gate
 379         int $0x15
 380         jnc A20GateEnabled                  # Jump if it suceeded
 381
 382 #
 383 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 384 #
 385
 386         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 387         jnz     Timeout8042                 # Jump if the 8042 timed out
 388         outw    %ax, $DELAY_PORT            # Delay 1 uS
 389         mov     $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 390         out     %al, $KBD_STATUS_PORT       # Send command to the 8042
 391         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 392         jnz     Timeout8042                 # Jump if the 8042 timed out
 393         mov     $ENABLE_A20_CMD, %al        # gate address bit 20 on
 394         out     %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 395         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 396         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 397 Delay25uS:
 398         outw    %ax, $DELAY_PORT            # Delay 1 uS
 399         loop    Delay25uS
 400 Timeout8042:
 401
 402
 403 A20GateEnabled:
 404
 405 #
 406 # DISABLE INTERRUPTS - Entering Protected Mode
 407 #
 408
 409         cli
 410
 411 #        mov ax,0b800h
 412 #        mov es,ax
 413 #        mov byte ptr es:[164],'c'
 414 #        mov ax,cs
 415 #        mov es,ax
 416
 417         .byte   0x66
 418         lgdt    gdtr
 419         .byte   0x66
 420         lidt    idtr
 421
 422         movl    %cr0, %eax
 423         orb     $1, %al
 424         movl    %eax, %cr0
 425
 426         movl $0x008, %eax                   # Flat data descriptor
 427         movl $0x00400000, %ebp              # Destination of EFILDR32
 428         movl $0x00070000, %ebx              # Length of copy
 429
 430 JUMP:
 431 # jmp far 0010:00020000
 432         .byte 0x66
 433         .byte 0xea
 434         .long 0x00020000
 435         .word 0x0010
 436
 437 Empty8042InputBuffer:
 438         movw $0, %cx
 439 Empty8042Loop:
 440         outw    %ax, $DELAY_PORT            # Delay 1us
 441         in      $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 442         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 443         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 444         ret
 445
 446 ##############################################################################
 447 # data
 448 ##############################################################################
 449
 450         .align 0x2
 451
 452         gdtr:    .long  GDT_END - GDT_BASE - 1  # GDT limit
 453         .long 0                                 # (GDT base gets set above)
 454 ##############################################################################
 455 #   global descriptor table (GDT)
 456 ##############################################################################
 457
 458         .align 0x2
 459
 460 GDT_BASE:
 461 # null descriptor
 462 .equ                NULL_SEL, .-GDT_BASE
 463         .word 0         # limit 15:0
 464         .word 0         # base 15:0
 465         .byte 0         # base 23:16
 466         .byte 0         # type
 467         .byte 0         # limit 19:16, flags
 468         .byte 0         # base 31:24
 469
 470 # linear data segment descriptor
 471 .equ            LINEAR_SEL, .-GDT_BASE
 472         .word 0xFFFF    # limit 0xFFFFF
 473         .word 0         # base 0
 474         .byte 0
 475         .byte 0x92      # present, ring 0, data, expand-up, writable
 476         .byte 0xCF              # page-granular, 32-bit
 477         .byte 0
 478
 479 # linear code segment descriptor
 480 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 481         .word 0xFFFF    # limit 0xFFFFF
 482         .word 0         # base 0
 483         .byte 0
 484         .byte 0x9A      # present, ring 0, data, expand-up, writable
 485         .byte 0xCF              # page-granular, 32-bit
 486         .byte 0
 487
 488 # system data segment descriptor
 489 .equ            SYS_DATA_SEL, .-GDT_BASE
 490         .word 0xFFFF    # limit 0xFFFFF
 491         .word 0         # base 0
 492         .byte 0
 493         .byte 0x92      # present, ring 0, data, expand-up, writable
 494         .byte 0xCF              # page-granular, 32-bit
 495         .byte 0
 496
 497 # system code segment descriptor
 498 .equ            SYS_CODE_SEL, .-GDT_BASE
 499         .word 0xFFFF    # limit 0xFFFFF
 500         .word 0         # base 0
 501         .byte 0
 502         .byte 0x9A      # present, ring 0, data, expand-up, writable
 503         .byte 0xCF              # page-granular, 32-bit
 504         .byte 0
 505
 506 # spare segment descriptor
 507 .equ        SPARE3_SEL, .-GDT_BASE
 508         .word 0         # limit 0xFFFFF
 509         .word 0         # base 0
 510         .byte 0
 511         .byte 0         # present, ring 0, data, expand-up, writable
 512         .byte 0         # page-granular, 32-bit
 513         .byte 0
 514
 515 # spare segment descriptor
 516 .equ        SPARE4_SEL, .-GDT_BASE
 517         .word 0         # limit 0xFFFFF
 518         .word 0         # base 0
 519         .byte 0
 520         .byte 0         # present, ring 0, data, expand-up, writable
 521         .byte 0         # page-granular, 32-bit
 522         .byte 0
 523
 524 # spare segment descriptor
 525 .equ        SPARE5_SEL, .-GDT_BASE
 526         .word 0         # limit 0xFFFFF
 527         .word 0         # base 0
 528         .byte 0
 529         .byte 0         # present, ring 0, data, expand-up, writable
 530         .byte 0         # page-granular, 32-bit
 531         .byte 0
 532
 533 GDT_END:
 534
 535         .align 0x2
 536
 537
 538
 539 idtr:  .long  IDT_END - IDT_BASE - 1 # IDT limit
 540         .long 0                      # (IDT base gets set above)
 541 ##############################################################################
 542 #   interrupt descriptor table (IDT)
 543 #
 544 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 545 #       mappings.  This implementation only uses the system timer and all other
 546 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 547 #       for convenience.
 548 ##############################################################################
 549
 550 #idt_tag db "IDT",0
 551         .align 0x2
 552
 553 IDT_BASE:
 554 # divide by zero (INT 0)
 555 .equ                DIV_ZERO_SEL, .-IDT_BASE
 556         .word 0            # offset 15:0
 557         .long SYS_CODE_SEL # selector 15:0
 558         .byte 0            # 0 for interrupt gate
 559         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 560         .word 0            # offset 31:16
 561
 562 # debug exception (INT 1)
 563 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 564         .word 0            # offset 15:0
 565         .long SYS_CODE_SEL # selector 15:0
 566         .byte 0            # 0 for interrupt gate
 567         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 568         .word 0            # offset 31:16
 569
 570 # NMI (INT 2)
 571 .equ                NMI_SEL, .-IDT_BASE
 572         .word 0            # offset 15:0
 573         .long SYS_CODE_SEL # selector 15:0
 574         .byte 0            # 0 for interrupt gate
 575         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 576         .word 0            # offset 31:16
 577
 578 # soft breakpoint (INT 3)
 579 .equ                BREAKPOINT_SEL, .-IDT_BASE
 580         .word 0            # offset 15:0
 581         .long SYS_CODE_SEL # selector 15:0
 582         .byte 0            # 0 for interrupt gate
 583         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 584         .word 0            # offset 31:16
 585
 586 # overflow (INT 4)
 587 .equ                OVERFLOW_SEL, .-IDT_BASE
 588         .word 0            # offset 15:0
 589         .long SYS_CODE_SEL # selector 15:0
 590         .byte 0            # 0 for interrupt gate
 591         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 592         .word 0            # offset 31:16
 593
 594 # bounds check (INT 5)
 595 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 596         .word 0            # offset 15:0
 597         .long SYS_CODE_SEL # selector 15:0
 598         .byte 0            # 0 for interrupt gate
 599         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 600         .word 0            # offset 31:16
 601
 602 # invalid opcode (INT 6)
 603 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 604         .word 0            # offset 15:0
 605         .long SYS_CODE_SEL # selector 15:0
 606         .byte 0            # 0 for interrupt gate
 607         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 608         .word 0            # offset 31:16
 609
 610 # device not available (INT 7)
 611 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 612          .word 0            # offset 15:0
 613         .long SYS_CODE_SEL # selector 15:0
 614         .byte 0            # 0 for interrupt gate
 615         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 616         .word 0            # offset 31:16
 617
 618 # double fault (INT 8)
 619 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 620         .word 0            # offset 15:0
 621         .long SYS_CODE_SEL # selector 15:0
 622         .byte 0            # 0 for interrupt gate
 623         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 624         .word 0            # offset 31:16
 625
 626 # Coprocessor segment overrun - reserved (INT 9)
 627 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 628         .word 0            # offset 15:0
 629         .long SYS_CODE_SEL # selector 15:0
 630         .byte 0            # 0 for interrupt gate
 631         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 632         .word 0            # offset 31:16
 633
 634 # invalid TSS (INT 0x0a)
 635 .equ                INVALID_TSS_SEL, .-IDT_BASE
 636         .word 0            # offset 15:0
 637         .long SYS_CODE_SEL # selector 15:0
 638         .byte 0            # 0 for interrupt gate
 639         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 640         .word 0            # offset 31:16
 641
 642 # segment not present (INT 0x0b)
 643 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 644         .word 0            # offset 15:0
 645         .long SYS_CODE_SEL # selector 15:0
 646         .byte 0            # 0 for interrupt gate
 647         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 648         .word 0            # offset 31:16
 649
 650 # stack fault (INT 0x0c)
 651 .equ                STACK_FAULT_SEL, .-IDT_BASE
 652         .word 0            # offset 15:0
 653         .long SYS_CODE_SEL # selector 15:0
 654         .byte 0            # 0 for interrupt gate
 655         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 656         .word 0            # offset 31:16
 657
 658 # general protection (INT 0x0d)
 659 .equ                GP_FAULT_SEL, .-IDT_BASE
 660         .word 0            # offset 15:0
 661         .long SYS_CODE_SEL # selector 15:0
 662         .byte 0            # 0 for interrupt gate
 663         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 664         .word 0            # offset 31:16
 665
 666 # page fault (INT 0x0e)
 667 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 668         .word 0            # offset 15:0
 669         .long SYS_CODE_SEL # selector 15:0
 670         .byte 0            # 0 for interrupt gate
 671         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 672         .word 0            # offset 31:16
 673
 674 # Intel reserved - do not use (INT 0x0f)
 675 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 676         .word 0            # offset 15:0
 677         .long SYS_CODE_SEL # selector 15:0
 678         .byte 0            # 0 for interrupt gate
 679         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 680         .word 0            # offset 31:16
 681
 682 # floating point error (INT 0x10)
 683 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 684         .word 0            # offset 15:0
 685         .long SYS_CODE_SEL # selector 15:0
 686         .byte 0            # 0 for interrupt gate
 687         .byte 0x0e |  0x80 # type = 386 interrupt gate, present
 688         .word 0            # offset 31:16
 689
 690 # alignment check (INT 0x11)
 691 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 692         .word 0            # offset 15:0
 693         .long 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 # machine check (INT 0x12)
 699 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 700         .word 0            # offset 15:0
 701         .long 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 # SIMD floating-point exception (INT 0x13)
 707 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 708         .word 0            # offset 15:0
 709         .long SYS_CODE_SEL # selector 15:0
 710         .byte 0            # 0 for interrupt gate
 711         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 712         .word 0            # offset 31:16
 713
 714 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 715                 .fill 85 * 8, 1, 0   # db (85 * 8) dup(0)
 716
 717 # IRQ 0 (System timer) - (INT 0x68)
 718 .equ                IRQ0_SEL, .-IDT_BASE
 719         .word 0            # offset 15:0
 720         .long 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 # IRQ 1 (8042 Keyboard controller) - (INT 0x69)
 726 .equ                IRQ1_SEL, .-IDT_BASE
 727         .word 0            # offset 15:0
 728         .long 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 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 0x6a)
 734 .equ                IRQ2_SEL, .-IDT_BASE
 735         .word 0            # offset 15:0
 736         .long 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 3 (COM 2) - (INT 0x6b)
 742 .equ                IRQ3_SEL, .-IDT_BASE
 743         .word 0            # offset 15:0
 744         .long 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 4 (COM 1) - (INT 0x6c)
 750 .equ                IRQ4_SEL, .-IDT_BASE
 751         .word 0            # offset 15:0
 752         .long 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 5 (LPT 2) - (INT 0x6d)
 758 .equ                IRQ5_SEL, .-IDT_BASE
 759         .word 0            # offset 15:0
 760         .long 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 6 (Floppy controller) - (INT 0x6e)
 766 .equ                IRQ6_SEL, .-IDT_BASE
 767         .word 0            # offset 15:0
 768         .long 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 7 (LPT 1) - (INT 0x6f)
 774 .equ                IRQ7_SEL, .-IDT_BASE
 775         .word 0            # offset 15:0
 776         .long 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 8 (RTC Alarm) - (INT 0x70)
 782 .equ                IRQ8_SEL, .-IDT_BASE
 783         .word 0            # offset 15:0
 784         .long 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 9 - (INT 0x71)
 790 .equ                IRQ9_SEL, .-IDT_BASE
 791         .word 0            # offset 15:0
 792         .long 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 10 - (INT 0x72)
 798 .equ                 IRQ10_SEL, .-IDT_BASE
 799         .word 0            # offset 15:0
 800         .long 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 11 - (INT 0x73)
 806 .equ                 IRQ11_SEL, .-IDT_BASE
 807         .word 0            # offset 15:0
 808         .long 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 12 (PS/2 mouse) - (INT 0x74)
 814 .equ                 IRQ12_SEL, .-IDT_BASE
 815         .word 0            # offset 15:0
 816         .long 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 13 (Floating point error) - (INT 0x75)
 822 .equ                 IRQ13_SEL, .-IDT_BASE
 823         .word 0            # offset 15:0
 824         .long 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 14 (Secondary IDE) - (INT 0x76)
 830 .equ                 IRQ14_SEL, .-IDT_BASE
 831         .word 0            # offset 15:0
 832         .long 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 # IRQ 15 (Primary IDE) - (INT 0x77)
 838 .equ                 IRQ15_SEL, .-IDT_BASE
 839         .word 0            # offset 15:0
 840         .long SYS_CODE_SEL # selector 15:0
 841         .byte 0            # 0 for interrupt gate
 842         .byte 0x0e |  0x80 # (10001110)type = 386 interrupt gate, present
 843         .word 0            # offset 31:16
 844
 845 IDT_END:
 846
 847         .align 0x2
 848
 849 MemoryMapSize:  .long 0
 850 MemoryMap:  .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         .long 0,0,0,0,0,0,0,0
 880
 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         .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
 883
 884         .org 0x0fe0
 885 MyStack:
 886         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 887         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 888         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 889         #    8259.c
 890
 891         int $8
 892         iret
 893
 894         int $9
 895         iret
 896
 897         int $10
 898         iret
 899
 900         int $11
 901         iret
 902
 903         int $12
 904         iret
 905
 906         int $13
 907         iret
 908
 909         int $14
 910         iret
 911
 912         int $15
 913         iret
 914
 915
 916         .org 0x0ffe
 917 BlockSignature:
 918         .word 0xaa55
 919
 920