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
  31 .global _start
  32 _start:
  33
  34 Ia32Jump:
  35   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  36   nop
  37
  38 OemId:               .ascii  "INTEL   "    # OemId                           - 8 bytes
  39 SectorSize:          .word  0              # Sector Size                     - 2 bytes
  40 SectorsPerCluster:   .byte  0              # Sector Per Cluster              - 1 byte
  41 ReservedSectors:     .word  0              # Reserved Sectors                - 2 bytes
  42 NoFats:              .byte  0              # Number of FATs                  - 1 byte
  43 RootEntries:         .word  0              # Root Entries                    - 2 bytes
  44 Sectors:             .word  0              # Number of Sectors               - 2 bytes
  45 Media:               .byte  0              # Media                           - 1 byte
  46 SectorsPerFat16:     .word  0              # Sectors Per FAT for FAT12/FAT16 - 2 byte
  47 SectorsPerTrack:     .word  0              # Sectors Per Track               - 2 bytes
  48 Heads:               .word  0              # Heads                           - 2 bytes
  49 HiddenSectors:       .long  0              # Hidden Sectors                  - 4 bytes
  50 LargeSectors:        .long  0              # Large Sectors                   - 4 bytes
  51
  52 #******************************************************************************
  53 #
  54 #The structure for FAT32 starting at offset 36 of the boot sector. (At this point,
  55 #the BPB/boot sector for FAT12 and FAT16 differs from the BPB/boot sector for FAT32.)
  56 #
  57 #******************************************************************************
  58
  59 SectorsPerFat32:     .long  0              # Sectors Per FAT for FAT32       - 4 bytes
  60 ExtFlags:            .word  0              # Mirror Flag                     - 2 bytes
  61 FSVersion:           .word  0              # File System Version             - 2 bytes
  62 RootCluster:         .long  0              # 1st Cluster Number of Root Dir  - 4 bytes
  63 FSInfo:              .word  0              # Sector Number of FSINFO         - 2 bytes
  64 BkBootSector:        .word  0              # Sector Number of Bk BootSector  - 2 bytes
  65 Reserved:            .fill 12,1,0          # Reserved Field                  - 12 bytes
  66 PhysicalDrive:       .byte  0              # Physical Drive Number           - 1 byte
  67 Reserved1:           .byte  0              # Reserved Field                  - 1 byte
  68 Signature:           .byte  0              # Extended Boot Signature         - 1 byte
  69 VolId:               .ascii  "    "        # Volume Serial Number            - 4 bytes
  70 FatLabel:            .ascii  "           " # Volume Label                    - 11 bytes
  71 FileSystemType:      .ascii  "FAT32   "    # File System Type                - 8 bytes
  72
  73 BootSectorEntryPoint:
  74         #ASSUME ds:@code
  75         #ASSUME ss:@code
  76       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  77       # cx = Start Cluster of EfiLdr
  78       # dx = Start Cluster of Efivar.bin
  79
  80 # Re use the BPB data stored in Boot Sector
  81         movw    $0x7c00, %bp
  82
  83
  84         pushw   %cx
  85 # Read Efivar.bin
  86 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  87         movw    $0x1900, %ax
  88         movw    %ax, %es
  89         testw   %dx, %dx
  90         jnz     CheckVarStoreSize
  91
  92         movb    $1, %al
  93 NoVarStore:
  94         pushw   %es
  95 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  96         movb    %al, %es:4
  97         jmp     SaveVolumeId
  98
  99 CheckVarStoreSize:
 100         movw    %dx, %di
 101         cmpl    $0x4000, %ds:2(%di)
 102         movb    $2, %al
 103         jne     NoVarStore
 104
 105 LoadVarStore:
 106         movb    $0, %al
 107         movb    %al, %es:4
 108         movw    (%di), %cx
 109 #       ES:DI = 1500:0
 110         xorw    %di, %di
 111         pushw   %es
 112         movw    $0x1500, %ax
 113         movw    %ax, %es
 114         call    ReadFile
 115 SaveVolumeId:
 116         popw    %es
 117         movw    VolId(%bp), %ax
 118         movw    %ax, %es:0                       # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
 119         movw    VolId+2(%bp), %ax
 120         movw    %ax, %es:2
 121
 122 # Read Efildr
 123         popw    %cx
 124 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 125 #       ES:DI = 2000:0, first cluster will be read again
 126         xorw    %di, %di                            # di = 0
 127         movw    $0x2000, %ax
 128         movw    %ax, %es
 129         call    ReadFile
 130         movw    %cs, %ax
 131         movw    %ax, %cs:JumpSegment
 132 JumpFarInstruction:
 133         .byte   0xea
 134 JumpOffset:
 135         .word   0x200
 136 JumpSegment:
 137         .word   0x2000
 138
 139
 140
 141
 142 # ****************************************************************************
 143 # ReadFile
 144 #
 145 # Arguments:
 146 #   CX    = Start Cluster of File
 147 #   ES:DI = Buffer to store file content read from disk
 148 #
 149 # Return:
 150 #   (ES << 4 + DI) = end of file content Buffer
 151 #
 152 # ****************************************************************************
 153 ReadFile:
 154 # si      = NumberOfClusters
 155 # cx      = ClusterNumber
 156 # dx      = CachedFatSectorNumber
 157 # ds:0000 = CacheFatSectorBuffer
 158 # es:di   = Buffer to load file
 159 # bx      = NextClusterNumber
 160         pusha
 161         movw    $1, %si                             # NumberOfClusters = 1
 162         pushw   %cx                                 # Push Start Cluster onto stack
 163         movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
 164 FatChainLoop:
 165         movw    %cx, %ax                            # ax = ClusterNumber
 166         andw    $0xfff8, %ax                        # ax = ax & 0xfff8
 167         cmpw    $0xfff8, %ax                        # See if this is the last cluster
 168         je      FoundLastCluster                    # Jump if last cluster found
 169         movw    %cx, %ax                            # ax = ClusterNumber
 170         shlw    $2, %ax                             # FatOffset = ClusterNumber * 4
 171         pushw   %si                                 # Save si
 172         movw    %ax, %si                            # si = FatOffset
 173         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 174         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 175         andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
 176         cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
 177         je      SkipFatRead
 178         movw    $2, %bx
 179         pushw   %es
 180         pushw   %ds
 181         popw    %es
 182         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 183         popw    %es
 184         movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
 185 SkipFatRead:
 186         movw    (%si), %bx                          # bx = NextClusterNumber
 187         movw    %cx, %ax                            # ax = ClusterNumber
 188         popw    %si                                 # Restore si
 189         decw    %bx                                 # bx = NextClusterNumber - 1
 190         cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
 191         jne     ReadClusters
 192         incw    %bx                                 # bx = NextClusterNumber
 193         incw    %si                                 # NumberOfClusters++
 194         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 195         jmp     FatChainLoop
 196 ReadClusters:
 197         incw    %bx
 198         popw    %ax                                 # ax = StartCluster
 199         pushw   %bx                                 # StartCluster = NextClusterNumber
 200         movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
 201         subw    $2, %ax                             # ax = StartCluster - 2
 202         xorb    %bh, %bh
 203         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 204         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 205         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 206         pushw   %ax                                 # save start sector
 207         movw    %si, %ax                            # ax = NumberOfClusters
 208         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 209         movw    %ax, %bx                            # bx = Number of Sectors
 210         popw    %ax                                 # ax = Start Sector
 211         call    ReadBlocks
 212         movw    $1, %si                             # NumberOfClusters = 1
 213         jmp     FatChainLoop
 214 FoundLastCluster:
 215         popw    %cx
 216         popa
 217         ret
 218
 219
 220 # ****************************************************************************
 221 # ReadBlocks - Reads a set of blocks from a block device
 222 #
 223 # AX    = Start LBA
 224 # BX    = Number of Blocks to Read
 225 # ES:DI = Buffer to store sectors read from disk
 226 # ****************************************************************************
 227
 228 # cx = Blocks
 229 # bx = NumberOfBlocks
 230 # si = StartLBA
 231
 232 ReadBlocks:
 233         pusha
 234         addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
 235         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 236         movl    %eax, %esi                          # esi = Start LBA
 237         movw    %bx, %cx                            # cx = Number of blocks to read
 238 ReadCylinderLoop:
 239         movw    $0x7bfc, %bp                        # bp = 0x7bfc
 240         movl    %esi, %eax                          # eax = Start LBA
 241         xorl    %edx, %edx                          # edx = 0
 242         movzwl  (%bp), %ebx                         # bx = MaxSector
 243         divl    %ebx                                # ax = StartLBA / MaxSector
 244         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 245
 246         movw    (%bp), %bx                          # bx = MaxSector
 247         subw    %dx, %bx                            # bx = MaxSector - Sector
 248         incw    %bx                                 # bx = MaxSector - Sector + 1
 249         cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
 250         jg      LimitTransfer
 251         movw    %cx, %bx                            # bx = Blocks
 252 LimitTransfer:
 253         pushw   %ax                                 # save ax
 254         movw    %es, %ax                            # ax = es
 255         shrw    $(BLOCK_SHIFT-4), %ax                # ax = Number of blocks into mem system
 256         andw    $0x7f, %ax                          # ax = Number of blocks into current seg
 257         addw    %bx, %ax                            # ax = End Block number of transfer
 258         cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
 259         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 260         subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
 261         subw    %ax, %bx                            # Decrease transfer size by block overage
 262 NotCrossing64KBoundry:
 263         popw    %ax                                 # restore ax
 264
 265         pushw   %cx
 266         movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
 267         xorw    %dx, %dx                            # dx = 0
 268         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 269                                                     # dx = ax % (MaxHead + 1) = Head
 270
 271         pushw   %bx                                 # Save number of blocks to transfer
 272         movb    %dl, %dh                            # dh = Head
 273         movw    $0x7c00, %bp                        # bp = 0x7c00
 274         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 275         movb    %al, %ch                            # ch = Cylinder
 276         movb    %bl, %al                            # al = Blocks
 277         movb    $2, %ah                             # ah = Function 2
 278         movw    %di, %bx                            # es:bx = Buffer address
 279         int     $0x13
 280         jc      DiskError
 281         popw    %bx
 282         popw    %cx
 283         movzwl  %bx, %ebx
 284         addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
 285         subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
 286         movw    %es, %ax
 287         shlw    $(BLOCK_SHIFT-4), %bx
 288         addw    %bx, %ax
 289         movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 290         cmpw    $0, %cx
 291         jne     ReadCylinderLoop
 292         popa
 293         ret
 294
 295 DiskError:
 296         pushw %cs
 297         popw %ds
 298         leaw ErrorString, %si
 299         movw $7, %cx
 300         jmp  PrintStringAndHalt
 301
 302 PrintStringAndHalt:
 303         movw $0xb800, %ax
 304         movw %ax, %es
 305         movw $160, %di
 306         rep
 307         movsw
 308 Halt:
 309         jmp   Halt
 310
 311 ErrorString:
 312         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
 313
 314         # .org     0x01fa  # Will cause build break
 315 LBAOffsetForBootSector:
 316         .long   0x0
 317
 318         # .org    0x01fe   # Will cause build break
 319         .word   0xaa55
 320
 321 #******************************************************************************
 322 #******************************************************************************
 323 #******************************************************************************
 324
 325 .equ                 DELAY_PORT, 0x0ed           # Port to use for 1uS delay
 326 .equ                 KBD_CONTROL_PORT, 0x060     # 8042 control port
 327 .equ                 KBD_STATUS_PORT, 0x064      # 8042 status port
 328 .equ                 WRITE_DATA_PORT_CMD, 0x0d1  # 8042 command to write the data port
 329 .equ                 ENABLE_A20_CMD, 0x0df       # 8042 command to enable A20
 330
 331 # .org     0x200  # Will cause build break
 332         jmp start
 333 Em64String:
 334         .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
 335
 336 start:
 337         movw %cs, %ax
 338         movw %ax, %ds
 339         movw %ax, %es
 340         movw %ax, %ss
 341         movw $MyStack, %sp
 342
 343 #        mov ax,0b800h
 344 #        mov es,ax
 345 #        mov byte ptr es:[160],'a'
 346 #        mov ax,cs
 347 #        mov es,ax
 348
 349         movl $0, %ebx
 350         leal MemoryMap, %edi
 351 MemMapLoop:
 352         movl $0xe820, %eax
 353         movl $20, %ecx
 354         movl $0x534d4150, %edx  # 0x534d4150 = 'SMAP'
 355         int  $0x15
 356         jc  MemMapDone
 357         addl $20, %edi
 358         cmpl $0, %ebx
 359         je  MemMapDone
 360         jmp MemMapLoop
 361 MemMapDone:
 362         leal MemoryMap, %eax
 363         subl %eax, %edi                     # Get the address of the memory map
 364         movl %edi, MemoryMapSize            # Save the size of the memory map
 365
 366         xorl    %ebx, %ebx
 367         movw    %cs, %bx                    # BX=segment
 368         shll    $4, %ebx                    # BX="linear" address of segment base
 369         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 370         movl    %eax, gdtr + 2            # Put address of gdt into the gdtr
 371         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 372         movl    %eax, idtr + 2            # Put address of idt into the idtr
 373         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 374
 375         addl $0x1000, %ebx                  # Source of EFI32
 376         movl %ebx, JUMP+2
 377         addl $0x1000, %ebx
 378         movl %ebx, %esi                     # Source of EFILDR32
 379
 380 #        mov ax,0b800h
 381 #        mov es,ax
 382 #        mov byte ptr es:[162],'b'
 383 #        mov ax,cs
 384 #        mov es,ax
 385
 386 #
 387 # Enable A20 Gate
 388 #
 389
 390         movw $0x2401, %ax                   # Enable A20 Gate
 391         int $0x15
 392         jnc A20GateEnabled                  # Jump if it suceeded
 393
 394 #
 395 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 396 #
 397
 398         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 399         jnz     Timeout8042                 # Jump if the 8042 timed out
 400         outw    %ax, $DELAY_PORT            # Delay 1 uS
 401         movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 402         outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
 403         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 404         jnz     Timeout8042                 # Jump if the 8042 timed out
 405         movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
 406         outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 407         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 408         movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
 409 Delay25uS:
 410         outw    %ax, $DELAY_PORT            # Delay 1 uS
 411         loopl   Delay25uS
 412 Timeout8042:
 413
 414
 415 A20GateEnabled:
 416
 417 #
 418 # DISABLE INTERRUPTS - Entering Protected Mode
 419 #
 420
 421         cli
 422
 423 #        mov ax,0b800h
 424 #        mov es,ax
 425 #        mov byte ptr es:[164],'c'
 426 #        mov ax,cs
 427 #        mov es,ax
 428
 429         .byte   0x66
 430         lgdt    gdtr
 431         .byte   0x66
 432         lidt    idtr
 433
 434         movl    %cr0, %eax
 435         orb     $1, %al
 436         movl    %eax, %cr0
 437
 438         movl $0x008, %eax                   # Flat data descriptor
 439         movl $0x00400000, %ebp              # Destination of EFILDR32
 440         movl $0x00070000, %ebx              # Length of copy
 441
 442 JUMP:
 443 # jmp far 0010:00020000
 444         .byte 0x66
 445         .byte 0xea
 446         .long 0x00020000
 447         .word 0x0010
 448
 449 Empty8042InputBuffer:
 450         movw $0, %cx
 451 Empty8042Loop:
 452         outw    %ax, $DELAY_PORT            # Delay 1us
 453         inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 454         andb    $0x2, %al                   # Check the Input Buffer Full Flag
 455         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 456         ret
 457
 458 ##############################################################################
 459 # data
 460 ##############################################################################
 461
 462         .p2align 1
 463
 464 gdtr:    .word GDT_END - GDT_BASE - 1
 465         .long 0                     # (GDT base gets set above)
 466 ##############################################################################
 467 #   global descriptor table (GDT)
 468 ##############################################################################
 469
 470         .p2align 1
 471
 472 GDT_BASE:
 473 # null descriptor
 474 .equ                NULL_SEL, .-GDT_BASE
 475         .word 0         # limit 15:0
 476         .word 0         # base 15:0
 477         .byte 0         # base 23:16
 478         .byte 0         # type
 479         .byte 0         # limit 19:16, flags
 480         .byte 0         # base 31:24
 481
 482 # linear data segment descriptor
 483 .equ            LINEAR_SEL, .-GDT_BASE
 484         .word 0xFFFF    # limit 0xFFFFF
 485         .word 0         # base 0
 486         .byte 0
 487         .byte 0x92      # present, ring 0, data, expand-up, writable
 488         .byte 0xCF      # page-granular, 32-bit
 489         .byte 0
 490
 491 # linear code segment descriptor
 492 .equ            LINEAR_CODE_SEL, .-GDT_BASE
 493         .word 0xFFFF    # limit 0xFFFFF
 494         .word 0         # base 0
 495         .byte 0
 496         .byte 0x9A      # present, ring 0, data, expand-up, writable
 497         .byte 0xCF      # page-granular, 32-bit
 498         .byte 0
 499
 500 # system data segment descriptor
 501 .equ            SYS_DATA_SEL, .-GDT_BASE
 502         .word 0xFFFF    # limit 0xFFFFF
 503         .word 0         # base 0
 504         .byte 0
 505         .byte 0x92      # present, ring 0, data, expand-up, writable
 506         .byte 0xCF      # page-granular, 32-bit
 507         .byte 0
 508
 509 # system code segment descriptor
 510 .equ            SYS_CODE_SEL, .-GDT_BASE
 511         .word 0xFFFF    # limit 0xFFFFF
 512         .word 0         # base 0
 513         .byte 0
 514         .byte 0x9A      # present, ring 0, data, expand-up, writable
 515         .byte 0xCF      # page-granular, 32-bit
 516         .byte 0
 517
 518 # spare segment descriptor
 519 .equ        SPARE3_SEL, .-GDT_BASE
 520         .word 0         # limit 0xFFFFF
 521         .word 0         # base 0
 522         .byte 0
 523         .byte 0         # present, ring 0, data, expand-up, writable
 524         .byte 0         # page-granular, 32-bit
 525         .byte 0
 526
 527 # spare segment descriptor
 528 .equ        SPARE4_SEL, .-GDT_BASE
 529         .word 0         # limit 0xFFFFF
 530         .word 0         # base 0
 531         .byte 0
 532         .byte 0         # present, ring 0, data, expand-up, writable
 533         .byte 0         # page-granular, 32-bit
 534         .byte 0
 535
 536 # spare segment descriptor
 537 .equ        SPARE5_SEL, .-GDT_BASE
 538         .word 0         # limit 0xFFFFF
 539         .word 0         # base 0
 540         .byte 0
 541         .byte 0         # present, ring 0, data, expand-up, writable
 542         .byte 0         # page-granular, 32-bit
 543         .byte 0
 544
 545 GDT_END:
 546
 547         .p2align 1
 548
 549
 550
 551 idtr:            .word IDT_END - IDT_BASE - 1
 552         .long 0                     # (IDT base gets set above)
 553 ##############################################################################
 554 #   interrupt descriptor table (IDT)
 555 #
 556 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 557 #       mappings.  This implementation only uses the system timer and all other
 558 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 559 #       for convenience.
 560 ##############################################################################
 561
 562 #idt_tag db "IDT",0
 563         .p2align 1
 564
 565 IDT_BASE:
 566 # divide by zero (INT 0)
 567 .equ                DIV_ZERO_SEL, .-IDT_BASE
 568         .word 0            # offset 15:0
 569         .word SYS_CODE_SEL # selector 15:0
 570         .byte 0            # 0 for interrupt gate
 571         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 572         .word 0            # offset 31:16
 573
 574 # debug exception (INT 1)
 575 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 576         .word 0            # offset 15:0
 577         .word SYS_CODE_SEL # selector 15:0
 578         .byte 0            # 0 for interrupt gate
 579         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 580         .word 0            # offset 31:16
 581
 582 # NMI (INT 2)
 583 .equ                NMI_SEL, .-IDT_BASE
 584         .word 0            # offset 15:0
 585         .word SYS_CODE_SEL # selector 15:0
 586         .byte 0            # 0 for interrupt gate
 587         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 588         .word 0            # offset 31:16
 589
 590 # soft breakpoint (INT 3)
 591 .equ                BREAKPOINT_SEL, .-IDT_BASE
 592         .word 0            # offset 15:0
 593         .word SYS_CODE_SEL # selector 15:0
 594         .byte 0            # 0 for interrupt gate
 595         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 596         .word 0            # offset 31:16
 597
 598 # overflow (INT 4)
 599 .equ                OVERFLOW_SEL, .-IDT_BASE
 600         .word 0            # offset 15:0
 601         .word SYS_CODE_SEL # selector 15:0
 602         .byte 0            # 0 for interrupt gate
 603         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 604         .word 0            # offset 31:16
 605
 606 # bounds check (INT 5)
 607 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 608         .word 0            # offset 15:0
 609         .word SYS_CODE_SEL # selector 15:0
 610         .byte 0            # 0 for interrupt gate
 611         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 612         .word 0            # offset 31:16
 613
 614 # invalid opcode (INT 6)
 615 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 616         .word 0            # offset 15:0
 617         .word SYS_CODE_SEL # selector 15:0
 618         .byte 0            # 0 for interrupt gate
 619         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 620         .word 0            # offset 31:16
 621
 622 # device not available (INT 7)
 623 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 624         .word 0            # offset 15:0
 625         .word SYS_CODE_SEL # selector 15:0
 626         .byte 0            # 0 for interrupt gate
 627         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 628         .word 0            # offset 31:16
 629
 630 # double fault (INT 8)
 631 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 632         .word 0            # offset 15:0
 633         .word SYS_CODE_SEL # selector 15:0
 634         .byte 0            # 0 for interrupt gate
 635         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 636         .word 0            # offset 31:16
 637
 638 # Coprocessor segment overrun - reserved (INT 9)
 639 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 640         .word 0            # offset 15:0
 641         .word SYS_CODE_SEL # selector 15:0
 642         .byte 0            # 0 for interrupt gate
 643         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 644         .word 0            # offset 31:16
 645
 646 # invalid TSS (INT 0ah)
 647 .equ                INVALID_TSS_SEL, .-IDT_BASE
 648         .word 0            # offset 15:0
 649         .word SYS_CODE_SEL # selector 15:0
 650         .byte 0            # 0 for interrupt gate
 651         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 652         .word 0            # offset 31:16
 653
 654 # segment not present (INT 0bh)
 655 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 656         .word 0            # offset 15:0
 657         .word SYS_CODE_SEL # selector 15:0
 658         .byte 0            # 0 for interrupt gate
 659         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 660         .word 0            # offset 31:16
 661
 662 # stack fault (INT 0ch)
 663 .equ                STACK_FAULT_SEL, .-IDT_BASE
 664         .word 0            # offset 15:0
 665         .word SYS_CODE_SEL # selector 15:0
 666         .byte 0            # 0 for interrupt gate
 667         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 668         .word 0            # offset 31:16
 669
 670 # general protection (INT 0dh)
 671 .equ                GP_FAULT_SEL, .-IDT_BASE
 672         .word 0            # offset 15:0
 673         .word SYS_CODE_SEL # selector 15:0
 674         .byte 0            # 0 for interrupt gate
 675         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 676         .word 0            # offset 31:16
 677
 678 # page fault (INT 0eh)
 679 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 680         .word 0            # offset 15:0
 681         .word SYS_CODE_SEL # selector 15:0
 682         .byte 0            # 0 for interrupt gate
 683         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 684         .word 0            # offset 31:16
 685
 686 # Intel reserved - do not use (INT 0fh)
 687 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 688         .word 0            # offset 15:0
 689         .word SYS_CODE_SEL # selector 15:0
 690         .byte 0            # 0 for interrupt gate
 691         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 692         .word 0            # offset 31:16
 693
 694 # floating point error (INT 10h)
 695 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 696         .word 0            # offset 15:0
 697         .word SYS_CODE_SEL # selector 15:0
 698         .byte 0            # 0 for interrupt gate
 699         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 700         .word 0            # offset 31:16
 701
 702 # alignment check (INT 11h)
 703 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 704         .word 0            # offset 15:0
 705         .word SYS_CODE_SEL # selector 15:0
 706         .byte 0            # 0 for interrupt gate
 707         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 708         .word 0            # offset 31:16
 709
 710 # machine check (INT 12h)
 711 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 712         .word 0            # offset 15:0
 713         .word SYS_CODE_SEL # selector 15:0
 714         .byte 0            # 0 for interrupt gate
 715         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 716         .word 0            # offset 31:16
 717
 718 # SIMD floating-point exception (INT 13h)
 719 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 720         .word 0            # offset 15:0
 721         .word SYS_CODE_SEL # selector 15:0
 722         .byte 0            # 0 for interrupt gate
 723         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 724         .word 0            # offset 31:16
 725
 726 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 727         .fill 85 * 8, 1, 0
 728
 729 # IRQ 0 (System timer) - (INT 68h)
 730 .equ                IRQ0_SEL, .-IDT_BASE
 731         .word 0            # offset 15:0
 732         .word SYS_CODE_SEL # selector 15:0
 733         .byte 0            # 0 for interrupt gate
 734         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 735         .word 0            # offset 31:16
 736
 737 # IRQ 1 (8042 Keyboard controller) - (INT 69h)
 738 .equ                IRQ1_SEL, .-IDT_BASE
 739         .word 0            # offset 15:0
 740         .word SYS_CODE_SEL # selector 15:0
 741         .byte 0            # 0 for interrupt gate
 742         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 743         .word 0            # offset 31:16
 744
 745 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
 746 .equ                IRQ2_SEL, .-IDT_BASE
 747         .word 0            # offset 15:0
 748         .word SYS_CODE_SEL # selector 15:0
 749         .byte 0            # 0 for interrupt gate
 750         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 751         .word 0            # offset 31:16
 752
 753 # IRQ 3 (COM 2) - (INT 6bh)
 754 .equ                IRQ3_SEL, .-IDT_BASE
 755         .word 0            # offset 15:0
 756         .word SYS_CODE_SEL # selector 15:0
 757         .byte 0            # 0 for interrupt gate
 758         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 759         .word 0            # offset 31:16
 760
 761 # IRQ 4 (COM 1) - (INT 6ch)
 762 .equ                IRQ4_SEL, .-IDT_BASE
 763         .word 0            # offset 15:0
 764         .word SYS_CODE_SEL # selector 15:0
 765         .byte 0            # 0 for interrupt gate
 766         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 767         .word 0            # offset 31:16
 768
 769 # IRQ 5 (LPT 2) - (INT 6dh)
 770 .equ                IRQ5_SEL, .-IDT_BASE
 771         .word 0            # offset 15:0
 772         .word SYS_CODE_SEL # selector 15:0
 773         .byte 0            # 0 for interrupt gate
 774         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 775         .word 0            # offset 31:16
 776
 777 # IRQ 6 (Floppy controller) - (INT 6eh)
 778 .equ                IRQ6_SEL, .-IDT_BASE
 779         .word 0            # offset 15:0
 780         .word SYS_CODE_SEL # selector 15:0
 781         .byte 0            # 0 for interrupt gate
 782         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 783         .word 0            # offset 31:16
 784
 785 # IRQ 7 (LPT 1) - (INT 6fh)
 786 .equ                IRQ7_SEL, .-IDT_BASE
 787         .word 0            # offset 15:0
 788         .word SYS_CODE_SEL # selector 15:0
 789         .byte 0            # 0 for interrupt gate
 790         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 791         .word 0            # offset 31:16
 792
 793 # IRQ 8 (RTC Alarm) - (INT 70h)
 794 .equ                IRQ8_SEL, .-IDT_BASE
 795         .word 0            # offset 15:0
 796         .word SYS_CODE_SEL # selector 15:0
 797         .byte 0            # 0 for interrupt gate
 798         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 799         .word 0            # offset 31:16
 800
 801 # IRQ 9 - (INT 71h)
 802 .equ                IRQ9_SEL, .-IDT_BASE
 803         .word 0            # offset 15:0
 804         .word SYS_CODE_SEL # selector 15:0
 805         .byte 0            # 0 for interrupt gate
 806         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 807         .word 0            # offset 31:16
 808
 809 # IRQ 10 - (INT 72h)
 810 .equ                 IRQ10_SEL, .-IDT_BASE
 811         .word 0            # offset 15:0
 812         .word SYS_CODE_SEL # selector 15:0
 813         .byte 0            # 0 for interrupt gate
 814         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 815         .word 0            # offset 31:16
 816
 817 # IRQ 11 - (INT 73h)
 818 .equ                 IRQ11_SEL, .-IDT_BASE
 819         .word 0            # offset 15:0
 820         .word SYS_CODE_SEL # selector 15:0
 821         .byte 0            # 0 for interrupt gate
 822         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 823         .word 0            # offset 31:16
 824
 825 # IRQ 12 (PS/2 mouse) - (INT 74h)
 826 .equ                 IRQ12_SEL, .-IDT_BASE
 827         .word 0            # offset 15:0
 828         .word SYS_CODE_SEL # selector 15:0
 829         .byte 0            # 0 for interrupt gate
 830         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 831         .word 0            # offset 31:16
 832
 833 # IRQ 13 (Floating point error) - (INT 75h)
 834 .equ                 IRQ13_SEL, .-IDT_BASE
 835         .word 0            # offset 15:0
 836         .word SYS_CODE_SEL # selector 15:0
 837         .byte 0            # 0 for interrupt gate
 838         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 839         .word 0            # offset 31:16
 840
 841 # IRQ 14 (Secondary IDE) - (INT 76h)
 842 .equ                 IRQ14_SEL, .-IDT_BASE
 843         .word 0            # offset 15:0
 844         .word SYS_CODE_SEL # selector 15:0
 845         .byte 0            # 0 for interrupt gate
 846         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 847         .word 0            # offset 31:16
 848
 849 # IRQ 15 (Primary IDE) - (INT 77h)
 850 .equ                 IRQ15_SEL, .-IDT_BASE
 851         .word 0            # offset 15:0
 852         .word SYS_CODE_SEL # selector 15:0
 853         .byte 0            # 0 for interrupt gate
 854         .byte 0x0e | 0x80  # type = 386 interrupt gate, present
 855         .word 0            # offset 31:16
 856
 857 IDT_END:
 858
 859         .p2align 1
 860
 861 MemoryMapSize:  .long 0
 862 MemoryMap:  .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         .long 0,0,0,0,0,0,0,0
 889         .long 0,0,0,0,0,0,0,0
 890         .long 0,0,0,0,0,0,0,0
 891         .long 0,0,0,0,0,0,0,0
 892
 893         .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
 894         .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
 895
 896         .org 0x0fe0
 897 MyStack:
 898         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
 899         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
 900         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
 901         #    8259.c
 902
 903         int $8
 904         iret
 905
 906         int $9
 907         iret
 908
 909         int $10
 910         iret
 911
 912         int $11
 913         iret
 914
 915         int $12
 916         iret
 917
 918         int $13
 919         iret
 920
 921         int $14
 922         iret
 923
 924         int $15
 925         iret
 926
 927
 928         .org 0x0ffe
 929 BlockSignature:
 930         .word 0xaa55
 931
 932