sys/boot/i386/btx/btx/btx.S

   1 /*
   2  * Copyright (c) 1998 Robert Nordier
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are freely
   6  * permitted provided that the above copyright notice and this
   7  * paragraph and the following disclaimer are duplicated in all
   8  * such forms.
   9  *
  10  * This software is provided "AS IS" and without any express or
  11  * implied warranties, including, without limitation, the implied
  12  * warranties of merchantability and fitness for a particular
  13  * purpose.
  14  *
  15  * $FreeBSD$
  16  */
  17
  18 /*
  19  * Memory layout.
  20  */
  21                 .set MEM_BTX,0x1000             # Start of BTX memory
  22                 .set MEM_ESP0,0x1800            # Supervisor stack
  23                 .set MEM_BUF,0x1800             # Scratch buffer
  24                 .set MEM_ESPR,0x5e00            # Real mode stack
  25                 .set MEM_IDT,0x5e00             # IDT
  26                 .set MEM_TSS,0x5f98             # TSS
  27                 .set MEM_MAP,0x6000             # I/O bit map
  28                 .set MEM_TSS_END,0x7fff         # End of TSS
  29                 .set MEM_ORG,0x9000             # BTX code
  30                 .set MEM_USR,0xa000             # Start of user memory
  31 /*
  32  * Paging control.
  33  */
  34                 .set PAG_SIZ,0x1000             # Page size
  35                 .set PAG_CNT,0x1000             # Pages to map
  36 /*
  37  * Fields in %eflags.
  38  */
  39                 .set PSL_RESERVED_DEFAULT,0x00000002
  40                 .set PSL_T,0x00000100           # Trap flag
  41                 .set PSL_I,0x00000200           # Interrupt enable flag
  42                 .set PSL_VM,0x00020000          # Virtual 8086 mode flag
  43                 .set PSL_AC,0x00040000          # Alignment check flag
  44 /*
  45  * Segment selectors.
  46  */
  47                 .set SEL_SCODE,0x8              # Supervisor code
  48                 .set SEL_SDATA,0x10             # Supervisor data
  49                 .set SEL_RCODE,0x18             # Real mode code
  50                 .set SEL_RDATA,0x20             # Real mode data
  51                 .set SEL_UCODE,0x28|3           # User code
  52                 .set SEL_UDATA,0x30|3           # User data
  53                 .set SEL_TSS,0x38               # TSS
  54 /*
  55  * Task state segment fields.
  56  */
  57                 .set TSS_ESP0,0x4               # PL 0 ESP
  58                 .set TSS_SS0,0x8                # PL 0 SS
  59                 .set TSS_MAP,0x66               # I/O bit map base
  60 /*
  61  * System calls.
  62  */
  63                 .set SYS_EXIT,0x0               # Exit
  64                 .set SYS_EXEC,0x1               # Exec
  65 /*
  66  * Fields in V86 interface structure.
  67  */
  68                 .set V86_CTL,0x0                # Control flags
  69                 .set V86_ADDR,0x4               # Int number/address
  70                 .set V86_ES,0x8                 # V86 ES
  71                 .set V86_DS,0xc                 # V86 DS
  72                 .set V86_FS,0x10                # V86 FS
  73                 .set V86_GS,0x14                # V86 GS
  74 /*
  75  * V86 control flags.
  76  */
  77                 .set V86F_ADDR,0x10000          # Segment:offset address
  78                 .set V86F_CALLF,0x20000         # Emulate far call
  79                 .set V86F_FLAGS,0x40000         # Return flags
  80 /*
  81  * Dump format control bytes.
  82  */
  83                 .set DMP_X16,0x1                # Word
  84                 .set DMP_X32,0x2                # Long
  85                 .set DMP_MEM,0x4                # Memory
  86                 .set DMP_EOL,0x8                # End of line
  87 /*
  88  * Screen defaults and assumptions.
  89  */
  90                 .set SCR_MAT,0x7                # Mode/attribute
  91                 .set SCR_COL,0x50               # Columns per row
  92                 .set SCR_ROW,0x19               # Rows per screen
  93 /*
  94  * BIOS Data Area locations.
  95  */
  96                 .set BDA_MEM,0x413              # Free memory
  97                 .set BDA_SCR,0x449              # Video mode
  98                 .set BDA_POS,0x450              # Cursor position
  99                 .set BDA_BOOT,0x472             # Boot howto flag
 100 /*
 101  * Derivations, for brevity.
 102  */
 103                 .set _ESP0H,MEM_ESP0>>0x8       # Byte 1 of ESP0
 104                 .set _TSSIO,MEM_MAP-MEM_TSS     # TSS I/O base
 105                 .set _TSSLM,MEM_TSS_END-MEM_TSS # TSS limit
 106                 .set _IDTLM,MEM_TSS-MEM_IDT-1   # IDT limit
 107 /*
 108  * Code segment.
 109  */
 110                 .globl start
 111                 .code16
 112 start:                                          # Start of code
 113 /*
 114  * BTX header.
 115  */
 116 btx_hdr:        .byte 0xeb                      # Machine ID
 117                 .byte 0xe                       # Header size
 118                 .ascii "BTX"                    # Magic
 119                 .byte 0x1                       # Major version
 120                 .byte 0x2                       # Minor version
 121                 .byte BTX_FLAGS                 # Flags
 122                 .word PAG_CNT-MEM_ORG>>0xc      # Paging control
 123                 .word break-start               # Text size
 124                 .long 0x0                       # Entry address
 125 /*
 126  * Initialization routine.
 127  */
 128 init:           cli                             # Disable interrupts
 129                 xor %ax,%ax                     # Zero/segment
 130                 mov %ax,%ss                     # Set up
 131                 mov $MEM_ESP0,%sp               #  stack
 132                 mov %ax,%es                     # Address
 133                 mov %ax,%ds                     #  data
 134                 pushl $0x2                      # Clear
 135                 popfl                           #  flags
 136 /*
 137  * Initialize memory.
 138  */
 139                 mov $MEM_IDT,%di                # Memory to initialize
 140                 mov $(MEM_ORG-MEM_IDT)/2,%cx    # Words to zero
 141                 rep                             # Zero-fill
 142                 stosw                           #  memory
 143 /*
 144  * Update real mode IDT for reflecting hardware interrupts.
 145  */
 146                 mov $intr20,%bx                 # Address first handler
 147                 mov $0x10,%cx                   # Number of handlers
 148                 mov $0x20*4,%di                 # First real mode IDT entry
 149 init.0:         mov %bx,(%di)                   # Store IP
 150                 inc %di                         # Address next
 151                 inc %di                         #  entry
 152                 stosw                           # Store CS
 153                 add $4,%bx                      # Next handler
 154                 loop init.0                     # Next IRQ
 155 /*
 156  * Create IDT.
 157  */
 158                 mov $MEM_IDT,%di
 159                 mov $idtctl,%si                 # Control string
 160 init.1:         lodsb                           # Get entry
 161                 cbw                             #  count
 162                 xchg %ax,%cx                    #  as word
 163                 jcxz init.4                     # If done
 164                 lodsb                           # Get segment
 165                 xchg %ax,%dx                    #  P:DPL:type
 166                 lodsw                           # Get control
 167                 xchg %ax,%bx                    #  set
 168                 lodsw                           # Get handler offset
 169                 mov $SEL_SCODE,%dh              # Segment selector
 170 init.2:         shr %bx                         # Handle this int?
 171                 jnc init.3                      # No
 172                 mov %ax,(%di)                   # Set handler offset
 173                 mov %dh,0x2(%di)                #  and selector
 174                 mov %dl,0x5(%di)                # Set P:DPL:type
 175                 add $0x4,%ax                    # Next handler
 176 init.3:         lea 0x8(%di),%di                # Next entry
 177                 loop init.2                     # Till set done
 178                 jmp init.1                      # Continue
 179 /*
 180  * Initialize TSS.
 181  */
 182 init.4:         movb $_ESP0H,TSS_ESP0+1(%di)    # Set ESP0
 183                 movb $SEL_SDATA,TSS_SS0(%di)    # Set SS0
 184                 movb $_TSSIO,TSS_MAP(%di)       # Set I/O bit map base
 185 /*
 186  * Bring up the system.
 187  */
 188                 mov $0x2820,%bx                 # Set protected mode
 189                 callw setpic                    #  IRQ offsets
 190                 lidt idtdesc                    # Set IDT
 191                 lgdt gdtdesc                    # Set GDT
 192                 mov %cr0,%eax                   # Switch to protected
 193                 inc %ax                         #  mode
 194                 mov %eax,%cr0                   #
 195                 ljmp $SEL_SCODE,$init.8         # To 32-bit code
 196                 .code32
 197 init.8:         xorl %ecx,%ecx                  # Zero
 198                 movb $SEL_SDATA,%cl             # To 32-bit
 199                 movw %cx,%ss                    #  stack
 200 /*
 201  * Launch user task.
 202  */
 203                 movb $SEL_TSS,%cl               # Set task
 204                 ltr %cx                         #  register
 205                 movl $MEM_USR,%edx              # User base address
 206                 movzwl %ss:BDA_MEM,%eax         # Get free memory
 207                 shll $0xa,%eax                  # To bytes
 208                 subl $0x1000,%eax               # Less arg space
 209                 subl %edx,%eax                  # Less base
 210                 movb $SEL_UDATA,%cl             # User data selector
 211                 pushl %ecx                      # Set SS
 212                 pushl %eax                      # Set ESP
 213                 push $0x202                     # Set flags (IF set)
 214                 push $SEL_UCODE                 # Set CS
 215                 pushl btx_hdr+0xc               # Set EIP
 216                 pushl %ecx                      # Set GS
 217                 pushl %ecx                      # Set FS
 218                 pushl %ecx                      # Set DS
 219                 pushl %ecx                      # Set ES
 220                 pushl %edx                      # Set EAX
 221                 movb $0x7,%cl                   # Set remaining
 222 init.9:         push $0x0                       #  general
 223                 loop init.9                     #  registers
 224 #ifdef BTX_SERIAL
 225                 call sio_init                   # setup the serial console
 226 #endif
 227                 popa                            #  and initialize
 228                 popl %es                        # Initialize
 229                 popl %ds                        #  user
 230                 popl %fs                        #  segment
 231                 popl %gs                        #  registers
 232                 iret                            # To user mode
 233 /*
 234  * Exit routine.
 235  */
 236 exit:           cli                             # Disable interrupts
 237                 movl $MEM_ESP0,%esp             # Clear stack
 238 /*
 239  * Turn off paging.
 240  */
 241                 movl %cr0,%eax                  # Get CR0
 242                 andl $~0x80000000,%eax          # Disable
 243                 movl %eax,%cr0                  #  paging
 244                 xorl %ecx,%ecx                  # Zero
 245                 movl %ecx,%cr3                  # Flush TLB
 246 /*
 247  * Restore the GDT in case we caught a kernel trap.
 248  */
 249                 lgdt gdtdesc                    # Set GDT
 250 /*
 251  * To 16 bits.
 252  */
 253                 ljmpw $SEL_RCODE,$exit.1        # Reload CS
 254                 .code16
 255 exit.1:         mov $SEL_RDATA,%cl              # 16-bit selector
 256                 mov %cx,%ss                     # Reload SS
 257                 mov %cx,%ds                     # Load
 258                 mov %cx,%es                     #  remaining
 259                 mov %cx,%fs                     #  segment
 260                 mov %cx,%gs                     #  registers
 261 /*
 262  * To real-address mode.
 263  */
 264                 dec %ax                         # Switch to
 265                 mov %eax,%cr0                   #  real mode
 266                 ljmp $0x0,$exit.2               # Reload CS
 267 exit.2:         xor %ax,%ax                     # Real mode segment
 268                 mov %ax,%ss                     # Reload SS
 269                 mov %ax,%ds                     # Address data
 270                 mov $0x7008,%bx                 # Set real mode
 271                 callw setpic                    #  IRQ offsets
 272                 lidt ivtdesc                    # Set IVT
 273 /*
 274  * Reboot or await reset.
 275  */
 276                 sti                             # Enable interrupts
 277                 testb $0x1,btx_hdr+0x7          # Reboot?
 278 exit.3:         jz exit.3                       # No
 279                 movw $0x1234, BDA_BOOT          # Do a warm boot
 280                 ljmp $0xf000,$0xfff0            # reboot the machine
 281 /*
 282  * Set IRQ offsets by reprogramming 8259A PICs.
 283  */
 284 setpic:         in $0x21,%al                    # Save master
 285                 push %ax                        #  IMR
 286                 in $0xa1,%al                    # Save slave
 287                 push %ax                        #  IMR
 288                 movb $0x11,%al                  # ICW1 to
 289                 outb %al,$0x20                  #  master,
 290                 outb %al,$0xa0                  #  slave
 291                 movb %bl,%al                    # ICW2 to
 292                 outb %al,$0x21                  #  master
 293                 movb %bh,%al                    # ICW2 to
 294                 outb %al,$0xa1                  #  slave
 295                 movb $0x4,%al                   # ICW3 to
 296                 outb %al,$0x21                  #  master
 297                 movb $0x2,%al                   # ICW3 to
 298                 outb %al,$0xa1                  #  slave
 299                 movb $0x1,%al                   # ICW4 to
 300                 outb %al,$0x21                  #  master,
 301                 outb %al,$0xa1                  #  slave
 302                 pop %ax                         # Restore slave
 303                 outb %al,$0xa1                  #  IMR
 304                 pop %ax                         # Restore master
 305                 outb %al,$0x21                  #  IMR
 306                 retw                            # To caller
 307                 .code32
 308 /*
 309  * Exception jump table.
 310  */
 311 intx00:         push $0x0                       # Int 0x0: #DE
 312                 jmp ex_noc                      # Divide error
 313                 push $0x1                       # Int 0x1: #DB
 314                 jmp ex_noc                      # Debug
 315                 push $0x3                       # Int 0x3: #BP
 316                 jmp ex_noc                      # Breakpoint
 317                 push $0x4                       # Int 0x4: #OF
 318                 jmp ex_noc                      # Overflow
 319                 push $0x5                       # Int 0x5: #BR
 320                 jmp ex_noc                      # BOUND range exceeded
 321                 push $0x6                       # Int 0x6: #UD
 322                 jmp ex_noc                      # Invalid opcode
 323                 push $0x7                       # Int 0x7: #NM
 324                 jmp ex_noc                      # Device not available
 325                 push $0x8                       # Int 0x8: #DF
 326                 jmp except                      # Double fault
 327                 push $0xa                       # Int 0xa: #TS
 328                 jmp except                      # Invalid TSS
 329                 push $0xb                       # Int 0xb: #NP
 330                 jmp except                      # Segment not present
 331                 push $0xc                       # Int 0xc: #SS
 332                 jmp except                      # Stack segment fault
 333                 push $0xd                       # Int 0xd: #GP
 334                 jmp except                      # General protection
 335                 push $0xe                       # Int 0xe: #PF
 336                 jmp except                      # Page fault
 337 intx10:         push $0x10                      # Int 0x10: #MF
 338                 jmp ex_noc                      # Floating-point error
 339 /*
 340  * Save a zero error code.
 341  */
 342 ex_noc:         pushl (%esp,1)                  # Duplicate int no
 343                 movb $0x0,0x4(%esp,1)           # Fake error code
 344 /*
 345  * Handle exception.
 346  */
 347 except:         cld                             # String ops inc
 348                 pushl %ds                       # Save
 349                 pushl %es                       #  most
 350                 pusha                           #  registers
 351                 pushl %gs                       # Set GS
 352                 pushl %fs                       # Set FS
 353                 pushl %ds                       # Set DS
 354                 pushl %es                       # Set ES
 355                 cmpw $SEL_SCODE,0x44(%esp,1)    # Supervisor mode?
 356                 jne except.1                    # No
 357                 pushl %ss                       # Set SS
 358                 jmp except.2                    # Join common code
 359 except.1:       pushl 0x50(%esp,1)              # Set SS
 360 except.2:       pushl 0x50(%esp,1)              # Set ESP
 361                 push $SEL_SDATA                 # Set up
 362                 popl %ds                        #  to
 363                 pushl %ds                       #  address
 364                 popl %es                        #  data
 365                 movl %esp,%ebx                  # Stack frame
 366                 movl $dmpfmt,%esi               # Dump format string
 367                 movl $MEM_BUF,%edi              # Buffer
 368                 pushl %edi                      # Dump to
 369                 call dump                       #  buffer
 370                 popl %esi                       #  and
 371                 call putstr                     #  display
 372                 leal 0x18(%esp,1),%esp          # Discard frame
 373                 popa                            # Restore
 374                 popl %es                        #  registers
 375                 popl %ds                        #  saved
 376                 cmpb $0x3,(%esp,1)              # Breakpoint?
 377                 je except.3                     # Yes
 378                 cmpb $0x1,(%esp,1)              # Debug?
 379                 jne except.2a                   # No
 380                 testl $PSL_T,0x10(%esp,1)       # Trap flag set?
 381                 jnz except.3                    # Yes
 382 except.2a:      jmp exit                        # Exit
 383 except.3:       leal 0x8(%esp,1),%esp           # Discard err, int no
 384                 iret                            # From interrupt
 385
 386 /*
 387  * Reboot the machine by setting the reboot flag and exiting
 388  */
 389 reboot:         orb $0x1,btx_hdr+0x7            # Set the reboot flag
 390                 jmp exit                        # Terminate BTX and reboot
 391
 392 /*
 393  * Protected Mode Hardware interrupt jump table.
 394  */
 395 intx20:         push $0x8                       # Int 0x20: IRQ0
 396                 jmp int_hw                      # V86 int 0x8
 397                 push $0x9                       # Int 0x21: IRQ1
 398                 jmp int_hw                      # V86 int 0x9
 399                 push $0xa                       # Int 0x22: IRQ2
 400                 jmp int_hw                      # V86 int 0xa
 401                 push $0xb                       # Int 0x23: IRQ3
 402                 jmp int_hw                      # V86 int 0xb
 403                 push $0xc                       # Int 0x24: IRQ4
 404                 jmp int_hw                      # V86 int 0xc
 405                 push $0xd                       # Int 0x25: IRQ5
 406                 jmp int_hw                      # V86 int 0xd
 407                 push $0xe                       # Int 0x26: IRQ6
 408                 jmp int_hw                      # V86 int 0xe
 409                 push $0xf                       # Int 0x27: IRQ7
 410                 jmp int_hw                      # V86 int 0xf
 411                 push $0x70                      # Int 0x28: IRQ8
 412                 jmp int_hw                      # V86 int 0x70
 413                 push $0x71                      # Int 0x29: IRQ9
 414                 jmp int_hw                      # V86 int 0x71
 415                 push $0x72                      # Int 0x2a: IRQ10
 416                 jmp int_hw                      # V86 int 0x72
 417                 push $0x73                      # Int 0x2b: IRQ11
 418                 jmp int_hw                      # V86 int 0x73
 419                 push $0x74                      # Int 0x2c: IRQ12
 420                 jmp int_hw                      # V86 int 0x74
 421                 push $0x75                      # Int 0x2d: IRQ13
 422                 jmp int_hw                      # V86 int 0x75
 423                 push $0x76                      # Int 0x2e: IRQ14
 424                 jmp int_hw                      # V86 int 0x76
 425                 push $0x77                      # Int 0x2f: IRQ15
 426                 jmp int_hw                      # V86 int 0x77
 427
 428 /*
 429  * Invoke real mode interrupt/function call from user mode with arguments.
 430  */
 431 intx31:         pushl $-1                       # Dummy int no for btx_v86
 432 /*
 433  * Invoke real mode interrupt/function call from protected mode.
 434  *
 435  * We place a trampoline on the user stack that will return to rret_tramp
 436  * which will reenter protected mode and then finally return to the user
 437  * client.
 438  *
 439  * Kernel frame %esi points to:         Real mode stack frame at MEM_ESPR:
 440  *
 441  * -0x00 user %ss                       -0x04 kernel %esp (with full frame)
 442  * -0x04 user %esp                      -0x08 btx_v86 pointer
 443  * -0x08 user %eflags                   -0x0c flags (only used if interrupt)
 444  * -0x0c user %cs                       -0x10 real mode CS:IP return trampoline
 445  * -0x10 user %eip                      -0x12 real mode flags
 446  * -0x14 int no                         -0x16 real mode CS:IP (target)
 447  * -0x18 %eax
 448  * -0x1c %ecx
 449  * -0x20 %edx
 450  * -0x24 %ebx
 451  * -0x28 %esp
 452  * -0x2c %ebp
 453  * -0x30 %esi
 454  * -0x34 %edi
 455  * -0x38 %gs
 456  * -0x3c %fs
 457  * -0x40 %ds
 458  * -0x44 %es
 459  * -0x48 zero %eax (hardware int only)
 460  * -0x4c zero %ecx (hardware int only)
 461  * -0x50 zero %edx (hardware int only)
 462  * -0x54 zero %ebx (hardware int only)
 463  * -0x58 zero %esp (hardware int only)
 464  * -0x5c zero %ebp (hardware int only)
 465  * -0x60 zero %esi (hardware int only)
 466  * -0x64 zero %edi (hardware int only)
 467  * -0x68 zero %gs (hardware int only)
 468  * -0x6c zero %fs (hardware int only)
 469  * -0x70 zero %ds (hardware int only)
 470  * -0x74 zero %es (hardware int only)
 471  */
 472 int_hw:         cld                             # String ops inc
 473                 pusha                           # Save gp regs
 474                 pushl %gs                       # Save
 475                 pushl %fs                       #  seg
 476                 pushl %ds                       #  regs
 477                 pushl %es
 478                 push $SEL_SDATA                 # Set up
 479                 popl %ds                        #  to
 480                 pushl %ds                       #  address
 481                 popl %es                        #  data
 482                 leal 0x44(%esp,1),%esi          # Base of frame
 483                 movl %esp,MEM_ESPR-0x04         # Save kernel stack pointer
 484                 movl -0x14(%esi),%eax           # Get Int no
 485                 cmpl $-1,%eax                   # Hardware interrupt?
 486                 jne intusr.1                    # Yes
 487 /*
 488  * v86 calls save the btx_v86 pointer on the real mode stack and read
 489  * the address and flags from the btx_v86 structure.  For interrupt
 490  * handler invocations (VM86 INTx requests), disable interrupts,
 491  * tracing, and alignment checking while the handler runs.
 492  */
 493                 movl $MEM_USR,%ebx              # User base
 494                 movl %ebx,%edx                  #  address
 495                 addl -0x4(%esi),%ebx            # User ESP
 496                 movl (%ebx),%ebp                # btx_v86 pointer
 497                 addl %ebp,%edx                  # Flatten btx_v86 ptr
 498                 movl %edx,MEM_ESPR-0x08         # Save btx_v86 ptr
 499                 movl V86_ADDR(%edx),%eax        # Get int no/address
 500                 movl V86_CTL(%edx),%edx         # Get control flags
 501                 movl -0x08(%esi),%ebx           # Save user flags in %ebx
 502                 testl $V86F_ADDR,%edx           # Segment:offset?
 503                 jnz intusr.4                    # Yes
 504                 andl $~(PSL_I|PSL_T|PSL_AC),%ebx # Disable interrupts, tracing,
 505                                                 #  and alignment checking for
 506                                                 #  interrupt handler
 507                 jmp intusr.3                    # Skip hardware interrupt
 508 /*
 509  * Hardware interrupts store a NULL btx_v86 pointer and use the
 510  * address (interrupt number) from the stack with empty flags.  Also,
 511  * push a dummy frame of zeros onto the stack for all the general
 512  * purpose and segment registers and clear %eflags.  This gives the
 513  * hardware interrupt handler a clean slate.
 514  */
 515 intusr.1:       xorl %edx,%edx                  # Control flags
 516                 movl %edx,MEM_ESPR-0x08         # NULL btx_v86 ptr
 517                 movl $12,%ecx                   # Frame is 12 dwords
 518 intusr.2:       pushl $0x0                      # Fill frame
 519                 loop intusr.2                   #  with zeros
 520                 movl $PSL_RESERVED_DEFAULT,%ebx # Set clean %eflags
 521 /*
 522  * Look up real mode IDT entry for hardware interrupts and VM86 INTx
 523  * requests.
 524  */
 525 intusr.3:       shll $0x2,%eax                  # Scale
 526                 movl (%eax),%eax                # Load int vector
 527                 jmp intusr.5                    # Skip CALLF test
 528 /*
 529  * Panic if V86F_CALLF isn't set with V86F_ADDR.
 530  */
 531 intusr.4:       testl $V86F_CALLF,%edx          # Far call?
 532                 jnz intusr.5                    # Ok
 533                 movl %edx,0x30(%esp,1)          # Place VM86 flags in int no
 534                 movl $badvm86,%esi              # Display bad
 535                 call putstr                     #  VM86 call
 536                 popl %es                        # Restore
 537                 popl %ds                        #  seg
 538                 popl %fs                        #  regs
 539                 popl %gs
 540                 popal                           # Restore gp regs
 541                 jmp ex_noc                      # Panic
 542 /*
 543  * %eax now holds the segment:offset of the function.
 544  * %ebx now holds the %eflags to pass to real mode.
 545  * %edx now holds the V86F_* flags.
 546  */
 547 intusr.5:       movw %bx,MEM_ESPR-0x12          # Pass user flags to real mode
 548                                                 #  target
 549 /*
 550  * If this is a v86 call, copy the seg regs out of the btx_v86 structure.
 551  */
 552                 movl MEM_ESPR-0x08,%ecx         # Get btx_v86 ptr
 553                 jecxz intusr.6                  # Skip for hardware ints
 554                 leal -0x44(%esi),%edi           # %edi => kernel stack seg regs
 555                 pushl %esi                      # Save
 556                 leal V86_ES(%ecx),%esi          # %esi => btx_v86 seg regs
 557                 movl $4,%ecx                    # Copy seg regs
 558                 rep                             #  from btx_v86
 559                 movsl                           #  to kernel stack
 560                 popl %esi                       # Restore
 561 intusr.6:       movl -0x08(%esi),%ebx           # Copy user flags to real
 562                 movl %ebx,MEM_ESPR-0x0c         #  mode return trampoline
 563                 movl $rret_tramp,%ebx           # Set return trampoline
 564                 movl %ebx,MEM_ESPR-0x10         #  CS:IP
 565                 movl %eax,MEM_ESPR-0x16         # Real mode target CS:IP
 566                 ljmpw $SEL_RCODE,$intusr.7      # Change to 16-bit segment
 567                 .code16
 568 intusr.7:       movl %cr0,%eax                  # Leave
 569                 dec %al                         #  protected
 570                 movl %eax,%cr0                  #  mode
 571                 ljmpw $0x0,$intusr.8
 572 intusr.8:       xorw %ax,%ax                    # Reset %ds
 573                 movw %ax,%ds                    #  and
 574                 movw %ax,%ss                    #  %ss
 575                 lidt ivtdesc                    # Set IVT
 576                 popl %es                        # Restore
 577                 popl %ds                        #  seg
 578                 popl %fs                        #  regs
 579                 popl %gs
 580                 popal                           # Restore gp regs
 581                 movw $MEM_ESPR-0x16,%sp         # Switch to real mode stack
 582                 iret                            # Call target routine
 583 /*
 584  * For the return to real mode we setup a stack frame like this on the real
 585  * mode stack.  Note that callf calls won't pop off the flags, but we just
 586  * ignore that by repositioning %sp to be just above the btx_v86 pointer
 587  * so it is aligned.  The stack is relative to MEM_ESPR.
 588  *
 589  * -0x04        kernel %esp
 590  * -0x08        btx_v86
 591  * -0x0c        %eax
 592  * -0x10        %ecx
 593  * -0x14        %edx
 594  * -0x18        %ebx
 595  * -0x1c        %esp
 596  * -0x20        %ebp
 597  * -0x24        %esi
 598  * -0x28        %edi
 599  * -0x2c        %gs
 600  * -0x30        %fs
 601  * -0x34        %ds
 602  * -0x38        %es
 603  * -0x3c        %eflags
 604  */
 605 rret_tramp:     movw $MEM_ESPR-0x08,%sp         # Reset stack pointer
 606                 pushal                          # Save gp regs
 607                 pushl %gs                       # Save
 608                 pushl %fs                       #  seg
 609                 pushl %ds                       #  regs
 610                 pushl %es
 611                 pushfl                          # Save %eflags
 612                 cli                             # Disable interrupts
 613                 std                             # String ops dec
 614                 xorw %ax,%ax                    # Reset seg
 615                 movw %ax,%ds                    #  regs
 616                 movw %ax,%es                    #  (%ss is already 0)
 617                 lidt idtdesc                    # Set IDT
 618                 lgdt gdtdesc                    # Set GDT
 619                 mov %cr0,%eax                   # Switch to protected
 620                 inc %ax                         #  mode
 621                 mov %eax,%cr0                   #
 622                 ljmp $SEL_SCODE,$rret_tramp.1   # To 32-bit code
 623                 .code32
 624 rret_tramp.1:   xorl %ecx,%ecx                  # Zero
 625                 movb $SEL_SDATA,%cl             # Setup
 626                 movw %cx,%ss                    #  32-bit
 627                 movw %cx,%ds                    #  seg
 628                 movw %cx,%es                    #  regs
 629                 movl MEM_ESPR-0x04,%esp         # Switch to kernel stack
 630                 leal 0x44(%esp,1),%esi          # Base of frame
 631                 andb $~0x2,tss_desc+0x5         # Clear TSS busy
 632                 movb $SEL_TSS,%cl               # Set task
 633                 ltr %cx                         #  register
 634 /*
 635  * Now we are back in protected mode.  The kernel stack frame set up
 636  * before entering real mode is still intact. For hardware interrupts,
 637  * leave the frame unchanged.
 638  */
 639                 cmpl $0,MEM_ESPR-0x08           # Leave saved regs unchanged
 640                 jz rret_tramp.3                 #  for hardware ints
 641 /*
 642  * For V86 calls, copy the registers off of the real mode stack onto
 643  * the kernel stack as we want their updated values.  Also, initialize
 644  * the segment registers on the kernel stack.
 645  *
 646  * Note that the %esp in the kernel stack after this is garbage, but popa
 647  * ignores it, so we don't have to fix it up.
 648  */
 649                 leal -0x18(%esi),%edi           # Kernel stack GP regs
 650                 pushl %esi                      # Save
 651                 movl $MEM_ESPR-0x0c,%esi        # Real mode stack GP regs
 652                 movl $8,%ecx                    # Copy GP regs from
 653                 rep                             #  real mode stack
 654                 movsl                           #  to kernel stack
 655                 movl $SEL_UDATA,%eax            # Selector for data seg regs
 656                 movl $4,%ecx                    # Initialize %ds,
 657                 rep                             #  %es, %fs, and
 658                 stosl                           #  %gs
 659 /*
 660  * For V86 calls, copy the saved seg regs on the real mode stack back
 661  * over to the btx_v86 structure.  Also, conditionally update the
 662  * saved eflags on the kernel stack based on the flags from the user.
 663  */
 664                 movl MEM_ESPR-0x08,%ecx         # Get btx_v86 ptr
 665                 leal V86_GS(%ecx),%edi          # %edi => btx_v86 seg regs
 666                 leal MEM_ESPR-0x2c,%esi         # %esi => real mode seg regs
 667                 xchgl %ecx,%edx                 # Save btx_v86 ptr
 668                 movl $4,%ecx                    # Copy seg regs
 669                 rep                             #  from real mode stack
 670                 movsl                           #  to btx_v86
 671                 popl %esi                       # Restore
 672                 movl V86_CTL(%edx),%edx         # Read V86 control flags
 673                 testl $V86F_FLAGS,%edx          # User wants flags?
 674                 jz rret_tramp.3                 # No
 675                 movl MEM_ESPR-0x3c,%eax         # Read real mode flags
 676                 movw %ax,-0x08(%esi)            # Update user flags (low 16)
 677 /*
 678  * Return to the user task
 679  */
 680 rret_tramp.3:   popl %es                        # Restore
 681                 popl %ds                        #  seg
 682                 popl %fs                        #  regs
 683                 popl %gs
 684                 popal                           # Restore gp regs
 685                 addl $4,%esp                    # Discard int no
 686                 iret                            # Return to user mode
 687
 688 /*
 689  * System Call.
 690  */
 691 intx30:         cmpl $SYS_EXEC,%eax             # Exec system call?
 692                 jne intx30.1                    # No
 693                 pushl %ss                       # Set up
 694                 popl %es                        #  all
 695                 pushl %es                       #  segment
 696                 popl %ds                        #  registers
 697                 pushl %ds                       #  for the
 698                 popl %fs                        #  program
 699                 pushl %fs                       #  we're
 700                 popl %gs                        #  invoking
 701                 movl $MEM_USR,%eax              # User base address
 702                 addl 0xc(%esp,1),%eax           # Change to user
 703                 leal 0x4(%eax),%esp             #  stack
 704                 popl %eax                       # Call
 705                 call *%eax                      #  program
 706 intx30.1:       orb $0x1,%ss:btx_hdr+0x7        # Flag reboot
 707                 jmp exit                        # Exit
 708 /*
 709  * Dump structure [EBX] to [EDI], using format string [ESI].
 710  */
 711 dump.0:         stosb                           # Save char
 712 dump:           lodsb                           # Load char
 713                 testb %al,%al                   # End of string?
 714                 jz dump.10                      # Yes
 715                 testb $0x80,%al                 # Control?
 716                 jz dump.0                       # No
 717                 movb %al,%ch                    # Save control
 718                 movb $'=',%al                   # Append
 719                 stosb                           #  '='
 720                 lodsb                           # Get offset
 721                 pushl %esi                      # Save
 722                 movsbl %al,%esi                 # To
 723                 addl %ebx,%esi                  #  pointer
 724                 testb $DMP_X16,%ch              # Dump word?
 725                 jz dump.1                       # No
 726                 lodsw                           # Get and
 727                 call hex16                      #  dump it
 728 dump.1:         testb $DMP_X32,%ch              # Dump long?
 729                 jz dump.2                       # No
 730                 lodsl                           # Get and
 731                 call hex32                      #  dump it
 732 dump.2:         testb $DMP_MEM,%ch              # Dump memory?
 733                 jz dump.8                       # No
 734                 pushl %ds                       # Save
 735                 testl $PSL_VM,0x50(%ebx)        # V86 mode?
 736                 jnz dump.3                      # Yes
 737                 verr 0x4(%esi)                  # Readable selector?
 738                 jnz dump.3                      # No
 739                 ldsl (%esi),%esi                # Load pointer
 740                 jmp dump.4                      # Join common code
 741 dump.3:         lodsl                           # Set offset
 742                 xchgl %eax,%edx                 # Save
 743                 lodsl                           # Get segment
 744                 shll $0x4,%eax                  #  * 0x10
 745                 addl %edx,%eax                  #  + offset
 746                 xchgl %eax,%esi                 # Set pointer
 747 dump.4:         movb $2,%dl                     # Num lines
 748 dump.4a:        movb $0x10,%cl                  # Bytes to dump
 749 dump.5:         lodsb                           # Get byte and
 750                 call hex8                       #  dump it
 751                 decb %cl                        # Keep count
 752                 jz dump.6a                      # If done
 753                 movb $'-',%al                   # Separator
 754                 cmpb $0x8,%cl                   # Half way?
 755                 je dump.6                       # Yes
 756                 movb $' ',%al                   # Use space
 757 dump.6:         stosb                           # Save separator
 758                 jmp dump.5                      # Continue
 759 dump.6a:        decb %dl                        # Keep count
 760                 jz dump.7                       # If done
 761                 movb $0xa,%al                   # Line feed
 762                 stosb                           # Save one
 763                 movb $7,%cl                     # Leading
 764                 movb $' ',%al                   #  spaces
 765 dump.6b:        stosb                           # Dump
 766                 decb %cl                        #  spaces
 767                 jnz dump.6b
 768                 jmp dump.4a                     # Next line
 769 dump.7:         popl %ds                        # Restore
 770 dump.8:         popl %esi                       # Restore
 771                 movb $0xa,%al                   # Line feed
 772                 testb $DMP_EOL,%ch              # End of line?
 773                 jnz dump.9                      # Yes
 774                 movb $' ',%al                   # Use spaces
 775                 stosb                           # Save one
 776 dump.9:         jmp dump.0                      # Continue
 777 dump.10:        stosb                           # Terminate string
 778                 ret                             # To caller
 779 /*
 780  * Convert EAX, AX, or AL to hex, saving the result to [EDI].
 781  */
 782 hex32:          pushl %eax                      # Save
 783                 shrl $0x10,%eax                 # Do upper
 784                 call hex16                      #  16
 785                 popl %eax                       # Restore
 786 hex16:          call hex16.1                    # Do upper 8
 787 hex16.1:        xchgb %ah,%al                   # Save/restore
 788 hex8:           pushl %eax                      # Save
 789                 shrb $0x4,%al                   # Do upper
 790                 call hex8.1                     #  4
 791                 popl %eax                       # Restore
 792 hex8.1:         andb $0xf,%al                   # Get lower 4
 793                 cmpb $0xa,%al                   # Convert
 794                 sbbb $0x69,%al                  #  to hex
 795                 das                             #  digit
 796                 orb $0x20,%al                   # To lower case
 797                 stosb                           # Save char
 798                 ret                             # (Recursive)
 799 /*
 800  * Output zero-terminated string [ESI] to the console.
 801  */
 802 putstr.0:       call putchr                     # Output char
 803 putstr:         lodsb                           # Load char
 804                 testb %al,%al                   # End of string?
 805                 jnz putstr.0                    # No
 806                 ret                             # To caller
 807 #ifdef BTX_SERIAL
 808                 .set SIO_PRT,SIOPRT             # Base port
 809                 .set SIO_FMT,SIOFMT             # 8N1
 810                 .set SIO_DIV,(115200/SIOSPD)    # 115200 / SPD
 811
 812 /*
 813  * void sio_init(void)
 814  */
 815 sio_init:       movw $SIO_PRT+0x3,%dx           # Data format reg
 816                 movb $SIO_FMT|0x80,%al          # Set format
 817                 outb %al,(%dx)                  #  and DLAB
 818                 pushl %edx                      # Save
 819                 subb $0x3,%dl                   # Divisor latch reg
 820                 movw $SIO_DIV,%ax               # Set
 821                 outw %ax,(%dx)                  #  BPS
 822                 popl %edx                       # Restore
 823                 movb $SIO_FMT,%al               # Clear
 824                 outb %al,(%dx)                  #  DLAB
 825                 incl %edx                       # Modem control reg
 826                 movb $0x3,%al                   # Set RTS,
 827                 outb %al,(%dx)                  #  DTR
 828                 incl %edx                       # Line status reg
 829
 830 /*
 831  * void sio_flush(void)
 832  */
 833 sio_flush.0:    call sio_getc.1                 # Get character
 834 sio_flush:      call sio_ischar                 # Check for character
 835                 jnz sio_flush.0                 # Till none
 836                 ret                             # To caller
 837
 838 /*
 839  * void sio_putc(int c)
 840  */
 841 sio_putc:       movw $SIO_PRT+0x5,%dx           # Line status reg
 842                 xor %ecx,%ecx                   # Timeout
 843                 movb $0x40,%ch                  #  counter
 844 sio_putc.1:     inb (%dx),%al                   # Transmitter
 845                 testb $0x20,%al                 #  buffer empty?
 846                 loopz sio_putc.1                # No
 847                 jz sio_putc.2                   # If timeout
 848                 movb 0x4(%esp,1),%al            # Get character
 849                 subb $0x5,%dl                   # Transmitter hold reg
 850                 outb %al,(%dx)                  # Write character
 851 sio_putc.2:     ret $0x4                        # To caller
 852
 853 /*
 854  * int sio_getc(void)
 855  */
 856 sio_getc:       call sio_ischar                 # Character available?
 857                 jz sio_getc                     # No
 858 sio_getc.1:     subb $0x5,%dl                   # Receiver buffer reg
 859                 inb (%dx),%al                   # Read character
 860                 ret                             # To caller
 861
 862 /*
 863  * int sio_ischar(void)
 864  */
 865 sio_ischar:     movw $SIO_PRT+0x5,%dx           # Line status register
 866                 xorl %eax,%eax                  # Zero
 867                 inb (%dx),%al                   # Received data
 868                 andb $0x1,%al                   #  ready?
 869                 ret                             # To caller
 870
 871 /*
 872  * Output character AL to the serial console.
 873  */
 874 putchr:         pusha                           # Save
 875                 cmpb $10, %al                   # is it a newline?
 876                 jne putchr.1                    #  no?, then leave
 877                 push $13                        # output a carriage
 878                 call sio_putc                   #  return first
 879                 movb $10, %al                   # restore %al
 880 putchr.1:       pushl %eax                      # Push the character
 881                                                 #  onto the stack
 882                 call sio_putc                   # Output the character
 883                 popa                            # Restore
 884                 ret                             # To caller
 885 #else
 886 /*
 887  * Output character AL to the console.
 888  */
 889 putchr:         pusha                           # Save
 890                 xorl %ecx,%ecx                  # Zero for loops
 891                 movb $SCR_MAT,%ah               # Mode/attribute
 892                 movl $BDA_POS,%ebx              # BDA pointer
 893                 movw (%ebx),%dx                 # Cursor position
 894                 movl $0xb8000,%edi              # Regen buffer (color)
 895                 cmpb %ah,BDA_SCR-BDA_POS(%ebx)  # Mono mode?
 896                 jne putchr.1                    # No
 897                 xorw %di,%di                    # Regen buffer (mono)
 898 putchr.1:       cmpb $0xa,%al                   # New line?
 899                 je putchr.2                     # Yes
 900                 xchgl %eax,%ecx                 # Save char
 901                 movb $SCR_COL,%al               # Columns per row
 902                 mulb %dh                        #  * row position
 903                 addb %dl,%al                    #  + column
 904                 adcb $0x0,%ah                   #  position
 905                 shll %eax                       #  * 2
 906                 xchgl %eax,%ecx                 # Swap char, offset
 907                 movw %ax,(%edi,%ecx,1)          # Write attr:char
 908                 incl %edx                       # Bump cursor
 909                 cmpb $SCR_COL,%dl               # Beyond row?
 910                 jb putchr.3                     # No
 911 putchr.2:       xorb %dl,%dl                    # Zero column
 912                 incb %dh                        # Bump row
 913 putchr.3:       cmpb $SCR_ROW,%dh               # Beyond screen?
 914                 jb putchr.4                     # No
 915                 leal 2*SCR_COL(%edi),%esi       # New top line
 916                 movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
 917                 rep                             # Scroll
 918                 movsl                           #  screen
 919                 movb $0x20,%al                  # Space
 920                 movb $SCR_COL,%cl               # Columns to clear
 921                 rep                             # Clear
 922                 stosw                           #  line
 923                 movb $SCR_ROW-1,%dh             # Bottom line
 924 putchr.4:       movw %dx,(%ebx)                 # Update position
 925                 popa                            # Restore
 926                 ret                             # To caller
 927 #endif
 928
 929                 .code16
 930 /*
 931  * Real Mode Hardware interrupt jump table.
 932  */
 933 intr20:         push $0x8                       # Int 0x20: IRQ0
 934                 jmp int_hwr                     # V86 int 0x8
 935                 push $0x9                       # Int 0x21: IRQ1
 936                 jmp int_hwr                     # V86 int 0x9
 937                 push $0xa                       # Int 0x22: IRQ2
 938                 jmp int_hwr                     # V86 int 0xa
 939                 push $0xb                       # Int 0x23: IRQ3
 940                 jmp int_hwr                     # V86 int 0xb
 941                 push $0xc                       # Int 0x24: IRQ4
 942                 jmp int_hwr                     # V86 int 0xc
 943                 push $0xd                       # Int 0x25: IRQ5
 944                 jmp int_hwr                     # V86 int 0xd
 945                 push $0xe                       # Int 0x26: IRQ6
 946                 jmp int_hwr                     # V86 int 0xe
 947                 push $0xf                       # Int 0x27: IRQ7
 948                 jmp int_hwr                     # V86 int 0xf
 949                 push $0x70                      # Int 0x28: IRQ8
 950                 jmp int_hwr                     # V86 int 0x70
 951                 push $0x71                      # Int 0x29: IRQ9
 952                 jmp int_hwr                     # V86 int 0x71
 953                 push $0x72                      # Int 0x2a: IRQ10
 954                 jmp int_hwr                     # V86 int 0x72
 955                 push $0x73                      # Int 0x2b: IRQ11
 956                 jmp int_hwr                     # V86 int 0x73
 957                 push $0x74                      # Int 0x2c: IRQ12
 958                 jmp int_hwr                     # V86 int 0x74
 959                 push $0x75                      # Int 0x2d: IRQ13
 960                 jmp int_hwr                     # V86 int 0x75
 961                 push $0x76                      # Int 0x2e: IRQ14
 962                 jmp int_hwr                     # V86 int 0x76
 963                 push $0x77                      # Int 0x2f: IRQ15
 964                 jmp int_hwr                     # V86 int 0x77
 965 /*
 966  * Reflect hardware interrupts in real mode.
 967  */
 968 int_hwr:        push %ax                        # Save
 969                 push %ds                        # Save
 970                 push %bp                        # Save
 971                 mov %sp,%bp                     # Address stack frame
 972                 xchg %bx,6(%bp)                 # Swap BX, int no
 973                 xor %ax,%ax                     # Set %ds:%bx to
 974                 shl $2,%bx                      #  point to
 975                 mov %ax,%ds                     #  IDT entry
 976                 mov (%bx),%ax                   # Load IP
 977                 mov 2(%bx),%bx                  # Load CS
 978                 xchg %ax,4(%bp)                 # Swap saved %ax,%bx with
 979                 xchg %bx,6(%bp)                 #  CS:IP of handler
 980                 pop %bp                         # Restore
 981                 pop %ds                         # Restore
 982                 lret                            # Jump to handler
 983
 984                 .p2align 4
 985 /*
 986  * Global descriptor table.
 987  */
 988 gdt:            .word 0x0,0x0,0x0,0x0           # Null entry
 989                 .word 0xffff,0x0,0x9a00,0xcf    # SEL_SCODE
 990                 .word 0xffff,0x0,0x9200,0xcf    # SEL_SDATA
 991                 .word 0xffff,0x0,0x9a00,0x0     # SEL_RCODE
 992                 .word 0xffff,0x0,0x9200,0x0     # SEL_RDATA
 993                 .word 0xffff,MEM_USR,0xfa00,0xcf# SEL_UCODE
 994                 .word 0xffff,MEM_USR,0xf200,0xcf# SEL_UDATA
 995 tss_desc:       .word _TSSLM,MEM_TSS,0x8900,0x0 # SEL_TSS
 996 gdt.1:
 997 /*
 998  * Pseudo-descriptors.
 999  */
1000 gdtdesc:        .word gdt.1-gdt-1,gdt,0x0       # GDT
1001 idtdesc:        .word _IDTLM,MEM_IDT,0x0        # IDT
1002 ivtdesc:        .word 0x400-0x0-1,0x0,0x0       # IVT
1003 /*
1004  * IDT construction control string.
1005  */
1006 idtctl:         .byte 0x10,  0x8e               # Int 0x0-0xf
1007                 .word 0x7dfb,intx00             #  (exceptions)
1008                 .byte 0x10,  0x8e               # Int 0x10
1009                 .word 0x1,   intx10             #  (exception)
1010                 .byte 0x10,  0x8e               # Int 0x20-0x2f
1011                 .word 0xffff,intx20             #  (hardware)
1012                 .byte 0x1,   0xee               # int 0x30
1013                 .word 0x1,   intx30             #  (system call)
1014                 .byte 0x2,   0xee               # Int 0x31-0x32
1015                 .word 0x1,   intx31             #  (V86, null)
1016                 .byte 0x0                       # End of string
1017 /*
1018  * Dump format string.
1019  */
1020 dmpfmt:         .byte '\n'                      # "\n"
1021                 .ascii "int"                    # "int="
1022                 .byte 0x80|DMP_X32,        0x40 # "00000000  "
1023                 .ascii "err"                    # "err="
1024                 .byte 0x80|DMP_X32,        0x44 # "00000000  "
1025                 .ascii "efl"                    # "efl="
1026                 .byte 0x80|DMP_X32,        0x50 # "00000000  "
1027                 .ascii "eip"                    # "eip="
1028                 .byte 0x80|DMP_X32|DMP_EOL,0x48 # "00000000\n"
1029                 .ascii "eax"                    # "eax="
1030                 .byte 0x80|DMP_X32,        0x34 # "00000000  "
1031                 .ascii "ebx"                    # "ebx="
1032                 .byte 0x80|DMP_X32,        0x28 # "00000000  "
1033                 .ascii "ecx"                    # "ecx="
1034                 .byte 0x80|DMP_X32,        0x30 # "00000000  "
1035                 .ascii "edx"                    # "edx="
1036                 .byte 0x80|DMP_X32|DMP_EOL,0x2c # "00000000\n"
1037                 .ascii "esi"                    # "esi="
1038                 .byte 0x80|DMP_X32,        0x1c # "00000000  "
1039                 .ascii "edi"                    # "edi="
1040                 .byte 0x80|DMP_X32,        0x18 # "00000000  "
1041                 .ascii "ebp"                    # "ebp="
1042                 .byte 0x80|DMP_X32,        0x20 # "00000000  "
1043                 .ascii "esp"                    # "esp="
1044                 .byte 0x80|DMP_X32|DMP_EOL,0x0  # "00000000\n"
1045                 .ascii "cs"                     # "cs="
1046                 .byte 0x80|DMP_X16,        0x4c # "0000  "
1047                 .ascii "ds"                     # "ds="
1048                 .byte 0x80|DMP_X16,        0xc  # "0000  "
1049                 .ascii "es"                     # "es="
1050                 .byte 0x80|DMP_X16,        0x8  # "0000  "
1051                 .ascii "  "                     # "  "
1052                 .ascii "fs"                     # "fs="
1053                 .byte 0x80|DMP_X16,        0x10 # "0000  "
1054                 .ascii "gs"                     # "gs="
1055                 .byte 0x80|DMP_X16,        0x14 # "0000  "
1056                 .ascii "ss"                     # "ss="
1057                 .byte 0x80|DMP_X16|DMP_EOL,0x4  # "0000\n"
1058                 .ascii "cs:eip"                 # "cs:eip="
1059                 .byte 0x80|DMP_MEM|DMP_EOL,0x48 # "00 00 ... 00 00\n"
1060                 .ascii "ss:esp"                 # "ss:esp="
1061                 .byte 0x80|DMP_MEM|DMP_EOL,0x0  # "00 00 ... 00 00\n"
1062                 .asciz "BTX halted\n"           # End
1063 /*
1064  * Bad VM86 call panic
1065  */
1066 badvm86:        .asciz "Invalid VM86 Request\n"
1067
1068 /*
1069  * End of BTX memory.
1070  */
1071                 .p2align 4
1072 break: