DuetPkg/BootSector/start32.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 #*    start32.asm
  13 #*
  14 #*   Abstract:
  15 #*
  16 #------------------------------------------------------------------------------
  17
  18         #.MODEL small
  19         .stack:
  20         .486p:
  21         .code:
  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 SectorSize:          .word  0              # Sector Size                     - 2 bytes
  36 SectorsPerCluster:   .byte  0              # Sector Per Cluster              - 1 byte
  37 ReservedSectors:     .word  0              # Reserved Sectors                - 2 bytes
  38 NoFats:              .byte  0              # Number of FATs                  - 1 byte
  39 RootEntries:         .word  0              # Root Entries                    - 2 bytes
  40 Sectors:             .word  0              # Number of Sectors               - 2 bytes
  41 Media:               .byte  0              # Media                           - 1 byte
  42 SectorsPerFat16:     .word  0              # Sectors Per FAT for FAT12/FAT16 - 2 byte
  43 SectorsPerTrack:     .word  0              # Sectors Per Track               - 2 bytes
  44 Heads:               .word  0              # Heads                           - 2 bytes
  45 HiddenSectors:       .long  0              # Hidden Sectors                  - 4 bytes
  46 LargeSectors:        .long  0              # Large Sectors                   - 4 bytes
  47
  48 #******************************************************************************
  49 #
  50 #The structure for FAT32 starting at offset 36 of the boot sector. (At this point,
  51 #the BPB/boot sector for FAT12 and FAT16 differs from the BPB/boot sector for FAT32.)
  52 #
  53 #******************************************************************************
  54
  55 SectorsPerFat32:     .long  0              # Sectors Per FAT for FAT32       - 4 bytes
  56 ExtFlags:            .word  0              # Mirror Flag                     - 2 bytes
  57 FSVersion:           .word  0              # File System Version             - 2 bytes
  58 RootCluster:         .long  0              # 1st Cluster Number of Root Dir  - 4 bytes
  59 FSInfo:              .word  0              # Sector Number of FSINFO         - 2 bytes
  60 BkBootSector:        .word  0              # Sector Number of Bk BootSector  - 2 bytes
  61 Reserved:            .fill 12,1,0          # Reserved Field                  - 12 bytes
  62 PhysicalDrive:       .byte  0              # Physical Drive Number           - 1 byte
  63 Reserved1:           .byte  0              # Reserved Field                  - 1 byte
  64 Signature:           .byte  0              # Extended Boot Signature         - 1 byte
  65 VolId:               .ascii  "    "        # Volume Serial Number            - 4 bytes
  66 FatLabel:            .ascii  "           " # Volume Label                    - 11 bytes
  67 FileSystemType:      .ascii  "FAT32   "    # File System Type                - 8 bytes
  68
  69 BootSectorEntryPoint:
  70         #ASSUME ds:@code
  71         #ASSUME ss:@code
  72       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  73       # cx = Start Cluster of EfiLdr
  74       # dx = Start Cluster of Efivar.bin
  75
  76 # Re use the BPB data stored in Boot Sector
  77         movw    $0x7c00, %bp
  78
  79
  80         pushw   %cx
  81 # Read Efivar.bin
  82 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  83         movw    $0x1900, %ax
  84         movw    %ax, %es
  85         testw   %dx, %dx
  86         jnz     CheckVarStoreSize
  87
  88         movb    $1, %al
  89 NoVarStore:
  90         pushw   %es
  91 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  92         movb    %al, %es:4
  93         jmp     SaveVolumeId
  94
  95 CheckVarStoreSize:
  96         movw    %dx, %di
  97         cmpl    $0x4000, %ds:2(%di)
  98         movb    $2, %al
  99         jne     NoVarStore
 100
 101 LoadVarStore:
 102         movb    $0, %al
 103         movb    %al, %es:4
 104         movw    (%di), %cx
 105 #       ES:DI = 1500:0
 106         xorw    %di, %di
 107         pushw   %es
 108         movw    $0x1500, %ax
 109         movw    %ax, %es
 110         call    ReadFile
 111 SaveVolumeId:
 112         popw    %es
 113         movw    VolId(%bp), %ax
 114         movw    %ax, %es:0                       # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 115         movw    VolId+2(%bp), %ax
 116         movw    %ax, %es:2
 117
 118 # Read Efildr
 119         popw    %cx
 120 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 121 #       ES:DI = 2000:0, first cluster will be read again
 122         xorw    %di, %di                            # di = 0
 123         movw    $0x2000, %ax
 124         movw    %ax, %es
 125         call    ReadFile
 126         movw    %cs, %ax
 127         movw    %ax, %cs:JumpSegment
 128 JumpFarInstruction:
 129         .byte   0xea
 130 JumpOffset:
 131         .word   0x200
 132 JumpSegment:
 133         .word   0x2000
 134
 135
 136
 137
 138 # ****************************************************************************
 139 # ReadFile
 140 #
 141 # Arguments:
 142 #   CX    = Start Cluster of File
 143 #   ES:DI = Buffer to store file content read from disk
 144 #
 145 # Return:
 146 #   (ES << 4 + DI) = end of file content Buffer
 147 #
 148 # ****************************************************************************
 149 ReadFile:
 150 # si      = NumberOfClusters
 151 # cx      = ClusterNumber
 152 # dx      = CachedFatSectorNumber
 153 # ds:0000 = CacheFatSectorBuffer
 154 # es:di   = Buffer to load file
 155 # bx      = NextClusterNumber
 156         pusha
 157         movw    $1, %si                             # NumberOfClusters = 1
 158         pushw   %cx                                 # Push Start Cluster onto stack
 159         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 160 FatChainLoop:
 161         movw    %cx, %ax                            # ax = ClusterNumber
 162         andw    $0xfff8, %ax                        # ax = ax & 0xfff8
 163         cmpw    $0xfff8, %ax                        # See if this is the last cluster
 164         je      FoundLastCluster                    # Jump if last cluster found
 165         movw    %cx, %ax                            # ax = ClusterNumber
 166         shlw    $2, %ax                             # FatOffset = ClusterNumber * 4
 167         pushw   %si                                 # Save si
 168         movw    %ax, %si                            # si = FatOffset
 169         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 170         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 171         andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
 172         cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
 173         je      SkipFatRead
 174         movw    $2, %bx
 175         pushw   %es
 176         pushw   %ds
 177         popw    %es
 178         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 179         popw    %es
 180         movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
 181 SkipFatRead:
 182         movw    (%si), %bx                          # bx = NextClusterNumber
 183         movw    %cx, %ax                            # ax = ClusterNumber
 184         popw    %si                                 # Restore si
 185         decw    %bx                                 # bx = NextClusterNumber - 1
 186         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 187         jne     ReadClusters
 188         incw    %bx                                 # bx = NextClusterNumber
 189         incw    %si                                 # NumberOfClusters++
 190         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 191         jmp     FatChainLoop
 192 ReadClusters:
 193         incw    %bx
 194         popw    %ax                                 # ax = StartCluster
 195         pushw   %bx                                 # StartCluster = NextClusterNumber
 196         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 197         subw    $2, %ax                             # ax = StartCluster - 2
 198         xorb    %bh, %bh
 199         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 200         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 201         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 202         pushw   %ax                                 # save start sector
 203         movw    %si, %ax                            # ax = NumberOfClusters
 204         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 205         movw    %ax, %bx                            # bx = Number of Sectors
 206         popw    %ax                                 # ax = Start Sector
 207         call    ReadBlocks
 208         movw    $1, %si                             # NumberOfClusters = 1
 209         jmp     FatChainLoop
 210 FoundLastCluster:
 211         popw    %cx
 212         popa
 213         ret
 214
 215
 216 # ****************************************************************************
 217 # ReadBlocks - Reads a set of blocks from a block device
 218 #
 219 # AX    = Start LBA
 220 # BX    = Number of Blocks to Read
 221 # ES:DI = Buffer to store sectors read from disk
 222 # ****************************************************************************
 223
 224 # cx = Blocks
 225 # bx = NumberOfBlocks
 226 # si = StartLBA
 227
 228 ReadBlocks:
 229         pusha
 230         addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
 231         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 232         movl    %eax, %esi                          # esi = Start LBA
 233         movw    %bx, %cx                            # cx = Number of blocks to read
 234 ReadCylinderLoop:
 235         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 236         movl    %esi, %eax                          # eax = Start LBA
 237         xorl    %edx, %edx                          # edx = 0
 238         movzwl  (%bp), %ebx                         # bx = MaxSector
 239         divl    %ebx                                # ax = StartLBA / MaxSector
 240         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 241
 242         movw    (%bp), %bx                          # bx = MaxSector
 243         subw    %dx, %bx                            # bx = MaxSector - Sector
 244         incw    %bx                                 # bx = MaxSector - Sector + 1
 245         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 246         jg      LimitTransfer
 247         movw    %cx, %bx                            # bx = Blocks
 248 LimitTransfer:
 249         pushw   %ax                                 # save ax
 250         movw    %es, %ax                            # ax = es
 251         shrw    $(BLOCK_SHIFT-4), %ax                # ax = Number of blocks into mem system
 252         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 253         addw    %bx, %ax                            # ax = End Block number of transfer
 254         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 255         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 256         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 257         subw    %ax, %bx                            # Decrease transfer size by block overage
 258 NotCrossing64KBoundry:
 259         popw    %ax                                 # restore ax
 260
 261         pushw   %cx
 262         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 263         xorw    %dx, %dx                            # dx = 0
 264         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 265                                                     # dx = ax % (MaxHead + 1) = Head
 266
 267         pushw   %bx                                 # Save number of blocks to transfer
 268         movb    %dl, %dh                            # dh = Head
 269         movw    $0x7c00, %bp                        # bp = 0x7c00
 270         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 271         movb    %al, %ch                            # ch = Cylinder
 272         movb    %bl, %al                            # al = Blocks
 273         movb    $2, %ah                             # ah = Function 2
 274         movw    %di, %bx                            # es:bx = Buffer address
 275         int     $0x13
 276         jc      DiskError
 277         popw    %bx
 278         popw    %cx
 279         movzwl  %bx, %ebx
 280         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 281         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 282         movw    %es, %ax
 283         shlw    $(BLOCK_SHIFT-4), %bx
 284         addw    %bx, %ax
 285         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 286         cmpw    $0, %cx
 287         jne     ReadCylinderLoop
 288         popa
 289         ret
 290
 291 DiskError:
 292         pushw %cs
 293         popw %ds
 294         leaw ErrorString, %si
 295         movw $7, %cx
 296         jmp  PrintStringAndHalt
 297
 298 PrintStringAndHalt:
 299         movw $0xb800, %ax
 300         movw %ax, %es
 301         movw $160, %di
 302         rep
 303         movsw
 304 Halt:
 305         jmp   Halt
 306
 307 ErrorString:
 308         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
 309
 310         # .org     0x01fa  # Will cause build break
 311 LBAOffsetForBootSector:
 312         .long   0x0
 313
 314         # .org    0x01fe   # Will cause build break
 315         .word   0xaa55
 316
 317 #******************************************************************************
 318 #******************************************************************************
 319 #******************************************************************************
 320
 321 .equ                 DELAY_PORT, 0x0ed           # Port to use for 1uS delay
 322 .equ                 KBD_CONTROL_PORT, 0x060     # 8042 control port
 323 .equ                 KBD_STATUS_PORT, 0x064      # 8042 status port
 324 .equ                 WRITE_DATA_PORT_CMD, 0x0d1  # 8042 command to write the data port
 325 .equ                 ENABLE_A20_CMD, 0x0df       # 8042 command to enable A20
 326
 327 # .org     0x200  # Will cause build break
 328         jmp start
 329 Em64String:
 330         .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
 331
 332 start:
 333         movw %cs, %ax
 334         movw %ax, %ds
 335         movw %ax, %es
 336         movw %ax, %ss
 337         movw $MyStack, %sp
 338
 339 #        mov ax,0b800h
 340 #        mov es,ax
 341 #        mov byte ptr es:[160],'a'
 342 #        mov ax,cs
 343 #        mov es,ax
 344
 345         movl $0, %ebx
 346         leal MemoryMap, %edi
 347 MemMapLoop:
 348         movl $0xe820, %eax
 349         movl $20, %ecx
 350         movl $0x534d4150, %edx  # 0x534d4150 = 'SMAP'
 351         int  $0x15
 352         jc  MemMapDone
 353         addl $20, %edi
 354         cmpl $0, %ebx
 355         je  MemMapDone
 356         jmp MemMapLoop
 357 MemMapDone:
 358         leal MemoryMap, %eax
 359         subl %eax, %edi                     # Get the address of the memory map
 360         movl %edi, MemoryMapSize            # Save the size of the memory map
 361
 362         xorl    %ebx, %ebx
 363         movw    %cs, %bx                    # BX=segment
 364         shll    $4, %ebx                    # BX="linear" address of segment base
 365         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 366         movl    %eax, gdtr + 2            # Put address of gdt into the gdtr
 367         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 368         movl    %eax, idtr + 2            # Put address of idt into the idtr
 369         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 370
 371         addl $0x1000, %ebx                  # Source of EFI32
 372         movl %ebx, JUMP+2
 373         addl $0x1000, %ebx
 374         movl %ebx, %esi                     # Source of EFILDR32
 375
 376 #        mov ax,0b800h
 377 #        mov es,ax
 378 #        mov byte ptr es:[162],'b'
 379 #        mov ax,cs
 380 #        mov es,ax
 381
 382 #
 383 # Enable A20 Gate
 384 #
 385
 386         movw $0x2401, %ax                   # Enable A20 Gate
 387         int $0x15
 388         jnc A20GateEnabled                  # Jump if it suceeded
 389
 390 #
 391 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 392 #
 393
 394         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 395         jnz     Timeout8042                 # Jump if the 8042 timed out
 396         outw    %ax, $DELAY_PORT            # Delay 1 uS
 397         movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 398         outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
 399         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 400         jnz     Timeout8042                 # Jump if the 8042 timed out
 401         movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
 402         outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 403         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 404         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 405 Delay25uS:
 406         outw    %ax, $DELAY_PORT            # Delay 1 uS
 407         loopl   Delay25uS
 408 Timeout8042:
 409
 410
 411 A20GateEnabled:
 412
 413 #
 414 # DISABLE INTERRUPTS - Entering Protected Mode
 415 #
 416
 417         cli
 418
 419 #        mov ax,0b800h
 420 #        mov es,ax
 421 #        mov byte ptr es:[164],'c'
 422 #        mov ax,cs
 423 #        mov es,ax
 424
 425         .byte   0x66
 426         lgdt    gdtr
 427         .byte   0x66
 428         lidt    idtr
 429
 430         movl    %cr0, %eax
 431         orb     $1, %al
 432         movl    %eax, %cr0
 433
 434         movl $0x008, %eax                   # Flat data descriptor
 435         movl $0x00400000, %ebp              # Destination of EFILDR32
 436         movl $0x00070000, %ebx              # Length of copy
 437
 438 JUMP:
 439 # jmp far 0010:00020000
 440         .byte 0x66
 441         .byte 0xea
 442         .long 0x00020000
 443         .word 0x0010
 444
 445 Empty8042InputBuffer:
 446         movw $0, %cx
 447 Empty8042Loop:
 448         outw    %ax, $DELAY_PORT            # Delay 1us
 449         inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 450         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 451         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 452         ret
 453
 454 ##############################################################################
 455 # data
 456 ##############################################################################
 457
 458         .align 0x2
 459
 460 gdtr:    .word GDT_END - GDT_BASE - 1
 461         .long 0                     # (GDT base gets set above)
 462 ##############################################################################
 463 #   global descriptor table (GDT)
 464 ##############################################################################
 465
 466         .align 0x2
 467
 468 GDT_BASE:
 469 # null descriptor
 470 .equ                NULL_SEL, .-GDT_BASE
 471         .word 0         # limit 15:0
 472         .word 0         # base 15:0
 473         .byte 0         # base 23:16
 474         .byte 0         # type
 475         .byte 0         # limit 19:16, flags
 476         .byte 0         # base 31:24
 477
 478 # linear data segment descriptor
 479 .equ            LINEAR_SEL, .-GDT_BASE
 480         .word 0xFFFF    # limit 0xFFFFF
 481         .word 0         # base 0
 482         .byte 0
 483         .byte 0x92      # present, ring 0, data, expand-up, writable
 484         .byte 0xCF      # page-granular, 32-bit
 485         .byte 0
 486
 487 # linear code segment descriptor
 488 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 489         .word 0xFFFF    # limit 0xFFFFF
 490         .word 0         # base 0
 491         .byte 0
 492         .byte 0x9A      # present, ring 0, data, expand-up, writable
 493         .byte 0xCF      # page-granular, 32-bit
 494         .byte 0
 495
 496 # system data segment descriptor
 497 .equ            SYS_DATA_SEL, .-GDT_BASE
 498         .word 0xFFFF    # limit 0xFFFFF
 499         .word 0         # base 0
 500         .byte 0
 501         .byte 0x92      # present, ring 0, data, expand-up, writable
 502         .byte 0xCF      # page-granular, 32-bit
 503         .byte 0
 504
 505 # system code segment descriptor
 506 .equ            SYS_CODE_SEL, .-GDT_BASE
 507         .word 0xFFFF    # limit 0xFFFFF
 508         .word 0         # base 0
 509         .byte 0
 510         .byte 0x9A      # present, ring 0, data, expand-up, writable
 511         .byte 0xCF      # page-granular, 32-bit
 512         .byte 0
 513
 514 # spare segment descriptor
 515 .equ        SPARE3_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        SPARE4_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 # spare segment descriptor
 533 .equ        SPARE5_SEL, .-GDT_BASE
 534         .word 0         # limit 0xFFFFF
 535         .word 0         # base 0
 536         .byte 0
 537         .byte 0         # present, ring 0, data, expand-up, writable
 538         .byte 0         # page-granular, 32-bit
 539         .byte 0
 540
 541 GDT_END:
 542
 543         .align 0x2
 544
 545
 546
 547 idtr:            .word IDT_END - IDT_BASE - 1
 548         .long 0                     # (IDT base gets set above)
 549 ##############################################################################
 550 #   interrupt descriptor table (IDT)
 551 #
 552 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 553 #       mappings.  This implementation only uses the system timer and all other
 554 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 555 #       for convenience.
 556 ##############################################################################
 557
 558 #idt_tag db "IDT",0
 559         .align 0x2
 560
 561 IDT_BASE:
 562 # divide by zero (INT 0)
 563 .equ                DIV_ZERO_SEL, .-IDT_BASE
 564         .word 0            # offset 15:0
 565         .word SYS_CODE_SEL # selector 15:0
 566         .byte 0            # 0 for interrupt gate
 567         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 568         .word 0            # offset 31:16
 569
 570 # debug exception (INT 1)
 571 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 572         .word 0            # offset 15:0
 573         .word SYS_CODE_SEL # selector 15:0
 574         .byte 0            # 0 for interrupt gate
 575         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 576         .word 0            # offset 31:16
 577
 578 # NMI (INT 2)
 579 .equ                NMI_SEL, .-IDT_BASE
 580         .word 0            # offset 15:0
 581         .word SYS_CODE_SEL # selector 15:0
 582         .byte 0            # 0 for interrupt gate
 583         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 584         .word 0            # offset 31:16
 585
 586 # soft breakpoint (INT 3)
 587 .equ                BREAKPOINT_SEL, .-IDT_BASE
 588         .word 0            # offset 15:0
 589         .word SYS_CODE_SEL # selector 15:0
 590         .byte 0            # 0 for interrupt gate
 591         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 592         .word 0            # offset 31:16
 593
 594 # overflow (INT 4)
 595 .equ                OVERFLOW_SEL, .-IDT_BASE
 596         .word 0            # offset 15:0
 597         .word SYS_CODE_SEL # selector 15:0
 598         .byte 0            # 0 for interrupt gate
 599         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 600         .word 0            # offset 31:16
 601
 602 # bounds check (INT 5)
 603 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 604         .word 0            # offset 15:0
 605         .word SYS_CODE_SEL # selector 15:0
 606         .byte 0            # 0 for interrupt gate
 607         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 608         .word 0            # offset 31:16
 609
 610 # invalid opcode (INT 6)
 611 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 612         .word 0            # offset 15:0
 613         .word SYS_CODE_SEL # selector 15:0
 614         .byte 0            # 0 for interrupt gate
 615         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 616         .word 0            # offset 31:16
 617
 618 # device not available (INT 7)
 619 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 620         .word 0            # offset 15:0
 621         .word SYS_CODE_SEL # selector 15:0
 622         .byte 0            # 0 for interrupt gate
 623         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 624         .word 0            # offset 31:16
 625
 626 # double fault (INT 8)
 627 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 628         .word 0            # offset 15:0
 629         .word SYS_CODE_SEL # selector 15:0
 630         .byte 0            # 0 for interrupt gate
 631         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 632         .word 0            # offset 31:16
 633
 634 # Coprocessor segment overrun - reserved (INT 9)
 635 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 636         .word 0            # offset 15:0
 637         .word SYS_CODE_SEL # selector 15:0
 638         .byte 0            # 0 for interrupt gate
 639         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 640         .word 0            # offset 31:16
 641
 642 # invalid TSS (INT 0ah)
 643 .equ                INVALID_TSS_SEL, .-IDT_BASE
 644         .word 0            # offset 15:0
 645         .word SYS_CODE_SEL # selector 15:0
 646         .byte 0            # 0 for interrupt gate
 647         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 648         .word 0            # offset 31:16
 649
 650 # segment not present (INT 0bh)
 651 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 652         .word 0            # offset 15:0
 653         .word SYS_CODE_SEL # selector 15:0
 654         .byte 0            # 0 for interrupt gate
 655         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 656         .word 0            # offset 31:16
 657
 658 # stack fault (INT 0ch)
 659 .equ                STACK_FAULT_SEL, .-IDT_BASE
 660         .word 0            # offset 15:0
 661         .word SYS_CODE_SEL # selector 15:0
 662         .byte 0            # 0 for interrupt gate
 663         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 664         .word 0            # offset 31:16
 665
 666 # general protection (INT 0dh)
 667 .equ                GP_FAULT_SEL, .-IDT_BASE
 668         .word 0            # offset 15:0
 669         .word SYS_CODE_SEL # selector 15:0
 670         .byte 0            # 0 for interrupt gate
 671         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 672         .word 0            # offset 31:16
 673
 674 # page fault (INT 0eh)
 675 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 676         .word 0            # offset 15:0
 677         .word SYS_CODE_SEL # selector 15:0
 678         .byte 0            # 0 for interrupt gate
 679         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 680         .word 0            # offset 31:16
 681
 682 # Intel reserved - do not use (INT 0fh)
 683 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 684         .word 0            # offset 15:0
 685         .word SYS_CODE_SEL # selector 15:0
 686         .byte 0            # 0 for interrupt gate
 687         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 688         .word 0            # offset 31:16
 689
 690 # floating point error (INT 10h)
 691 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 692         .word 0            # offset 15:0
 693         .word SYS_CODE_SEL # selector 15:0
 694         .byte 0            # 0 for interrupt gate
 695         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 696         .word 0            # offset 31:16
 697
 698 # alignment check (INT 11h)
 699 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 700         .word 0            # offset 15:0
 701         .word SYS_CODE_SEL # selector 15:0
 702         .byte 0            # 0 for interrupt gate
 703         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 704         .word 0            # offset 31:16
 705
 706 # machine check (INT 12h)
 707 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 708         .word 0            # offset 15:0
 709         .word SYS_CODE_SEL # selector 15:0
 710         .byte 0            # 0 for interrupt gate
 711         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 712         .word 0            # offset 31:16
 713
 714 # SIMD floating-point exception (INT 13h)
 715 .equ                SIMD_EXCEPTION_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  # type = 386 interrupt gate, present
 720         .word 0            # offset 31:16
 721
 722 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 723         .fill 85 * 8, 1, 0
 724
 725 # IRQ 0 (System timer) - (INT 68h)
 726 .equ                IRQ0_SEL, .-IDT_BASE
 727         .word 0            # offset 15:0
 728         .word SYS_CODE_SEL # selector 15:0
 729         .byte 0            # 0 for interrupt gate
 730         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 731         .word 0            # offset 31:16
 732
 733 # IRQ 1 (8042 Keyboard controller) - (INT 69h)
 734 .equ                IRQ1_SEL, .-IDT_BASE
 735         .word 0            # offset 15:0
 736         .word SYS_CODE_SEL # selector 15:0
 737         .byte 0            # 0 for interrupt gate
 738         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 739         .word 0            # offset 31:16
 740
 741 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
 742 .equ                IRQ2_SEL, .-IDT_BASE
 743         .word 0            # offset 15:0
 744         .word SYS_CODE_SEL # selector 15:0
 745         .byte 0            # 0 for interrupt gate
 746         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 747         .word 0            # offset 31:16
 748
 749 # IRQ 3 (COM 2) - (INT 6bh)
 750 .equ                IRQ3_SEL, .-IDT_BASE
 751         .word 0            # offset 15:0
 752         .word SYS_CODE_SEL # selector 15:0
 753         .byte 0            # 0 for interrupt gate
 754         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 755         .word 0            # offset 31:16
 756
 757 # IRQ 4 (COM 1) - (INT 6ch)
 758 .equ                IRQ4_SEL, .-IDT_BASE
 759         .word 0            # offset 15:0
 760         .word SYS_CODE_SEL # selector 15:0
 761         .byte 0            # 0 for interrupt gate
 762         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 763         .word 0            # offset 31:16
 764
 765 # IRQ 5 (LPT 2) - (INT 6dh)
 766 .equ                IRQ5_SEL, .-IDT_BASE
 767         .word 0            # offset 15:0
 768         .word SYS_CODE_SEL # selector 15:0
 769         .byte 0            # 0 for interrupt gate
 770         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 771         .word 0            # offset 31:16
 772
 773 # IRQ 6 (Floppy controller) - (INT 6eh)
 774 .equ                IRQ6_SEL, .-IDT_BASE
 775         .word 0            # offset 15:0
 776         .word SYS_CODE_SEL # selector 15:0
 777         .byte 0            # 0 for interrupt gate
 778         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 779         .word 0            # offset 31:16
 780
 781 # IRQ 7 (LPT 1) - (INT 6fh)
 782 .equ                IRQ7_SEL, .-IDT_BASE
 783         .word 0            # offset 15:0
 784         .word SYS_CODE_SEL # selector 15:0
 785         .byte 0            # 0 for interrupt gate
 786         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 787         .word 0            # offset 31:16
 788
 789 # IRQ 8 (RTC Alarm) - (INT 70h)
 790 .equ                IRQ8_SEL, .-IDT_BASE
 791         .word 0            # offset 15:0
 792         .word SYS_CODE_SEL # selector 15:0
 793         .byte 0            # 0 for interrupt gate
 794         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 795         .word 0            # offset 31:16
 796
 797 # IRQ 9 - (INT 71h)
 798 .equ                IRQ9_SEL, .-IDT_BASE
 799         .word 0            # offset 15:0
 800         .word SYS_CODE_SEL # selector 15:0
 801         .byte 0            # 0 for interrupt gate
 802         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 803         .word 0            # offset 31:16
 804
 805 # IRQ 10 - (INT 72h)
 806 .equ                 IRQ10_SEL, .-IDT_BASE
 807         .word 0            # offset 15:0
 808         .word SYS_CODE_SEL # selector 15:0
 809         .byte 0            # 0 for interrupt gate
 810         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 811         .word 0            # offset 31:16
 812
 813 # IRQ 11 - (INT 73h)
 814 .equ                 IRQ11_SEL, .-IDT_BASE
 815         .word 0            # offset 15:0
 816         .word SYS_CODE_SEL # selector 15:0
 817         .byte 0            # 0 for interrupt gate
 818         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 819         .word 0            # offset 31:16
 820
 821 # IRQ 12 (PS/2 mouse) - (INT 74h)
 822 .equ                 IRQ12_SEL, .-IDT_BASE
 823         .word 0            # offset 15:0
 824         .word SYS_CODE_SEL # selector 15:0
 825         .byte 0            # 0 for interrupt gate
 826         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 827         .word 0            # offset 31:16
 828
 829 # IRQ 13 (Floating point error) - (INT 75h)
 830 .equ                 IRQ13_SEL, .-IDT_BASE
 831         .word 0            # offset 15:0
 832         .word SYS_CODE_SEL # selector 15:0
 833         .byte 0            # 0 for interrupt gate
 834         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 835         .word 0            # offset 31:16
 836
 837 # IRQ 14 (Secondary IDE) - (INT 76h)
 838 .equ                 IRQ14_SEL, .-IDT_BASE
 839         .word 0            # offset 15:0
 840         .word SYS_CODE_SEL # selector 15:0
 841         .byte 0            # 0 for interrupt gate
 842         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 843         .word 0            # offset 31:16
 844
 845 # IRQ 15 (Primary IDE) - (INT 77h)
 846 .equ                 IRQ15_SEL, .-IDT_BASE
 847         .word 0            # offset 15:0
 848         .word SYS_CODE_SEL # selector 15:0
 849         .byte 0            # 0 for interrupt gate
 850         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 851         .word 0            # offset 31:16
 852
 853 IDT_END:
 854
 855         .align 0x2
 856
 857 MemoryMapSize:  .long 0
 858 MemoryMap:  .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         .long 0,0,0,0,0,0,0,0
 881         .long 0,0,0,0,0,0,0,0
 882         .long 0,0,0,0,0,0,0,0
 883         .long 0,0,0,0,0,0,0,0
 884         .long 0,0,0,0,0,0,0,0
 885         .long 0,0,0,0,0,0,0,0
 886         .long 0,0,0,0,0,0,0,0
 887         .long 0,0,0,0,0,0,0,0
 888
 889         .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
 890         .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
 891
 892         .org 0x0fe0
 893 MyStack:
 894         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 895         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 896         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 897         #    8259.c
 898
 899         int $8
 900         iret
 901
 902         int $9
 903         iret
 904
 905         int $10
 906         iret
 907
 908         int $11
 909         iret
 910
 911         int $12
 912         iret
 913
 914         int $13
 915         iret
 916
 917         int $14
 918         iret
 919
 920         int $15
 921         iret
 922
 923
 924         .org 0x0ffe
 925 BlockSignature:
 926         .word 0xaa55
 927
 928