loader/dos/dosvm.c

   1 /*
   2  * DOS Virtual Machine
   3  *
   4  * Copyright 1998 Ove Kåven
   5  *
   6  * This code hasn't been completely cleaned up yet.
   7  */
   8
   9 #include "config.h"
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <errno.h>
  15 #include <fcntl.h>
  16 #include <signal.h>
  17 #include <unistd.h>
  18 #include <sys/time.h>
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21
  22 #include "wine/winbase16.h"
  23 #include "wine/exception.h"
  24 #include "windef.h"
  25 #include "winbase.h"
  26 #include "wingdi.h"
  27 #include "winuser.h"
  28 #include "winnt.h"
  29 #include "wincon.h"
  30
  31 #include "callback.h"
  32 #include "msdos.h"
  33 #include "file.h"
  34 #include "miscemu.h"
  35 #include "dosexe.h"
  36 #include "dosmod.h"
  37 #include "stackframe.h"
  38 #include "debugtools.h"
  39
  40 DECLARE_DEBUG_CHANNEL(int)
  41 DECLARE_DEBUG_CHANNEL(module)
  42 DECLARE_DEBUG_CHANNEL(relay)
  43
  44 #ifdef MZ_SUPPORTED
  45
  46 #ifdef HAVE_SYS_VM86_H
  47 # include <sys/vm86.h>
  48 #endif
  49 #ifdef HAVE_SYS_MMAN_H
  50 # include <sys/mman.h>
  51 #endif
  52
  53 #define IF_CLR(ctx)     ((ctx)->EFlags &= ~VIF_MASK)
  54 #define IF_SET(ctx)     ((ctx)->EFlags |= VIF_MASK)
  55 #define IF_ENABLED(ctx) ((ctx)->EFlags & VIF_MASK)
  56 #define SET_PEND(ctx)   ((ctx)->EFlags |= VIP_MASK)
  57 #define CLR_PEND(ctx)   ((ctx)->EFlags &= ~VIP_MASK)
  58 #define IS_PEND(ctx)    ((ctx)->EFlags & VIP_MASK)
  59
  60 #undef TRY_PICRETURN
  61
  62 typedef struct _DOSEVENT {
  63   int irq,priority;
  64   void (*relay)(CONTEXT86*,void*);
  65   void *data;
  66   struct _DOSEVENT *next;
  67 } DOSEVENT, *LPDOSEVENT;
  68
  69 static struct _DOSEVENT *pending_event, *current_event;
  70 static int sig_sent, entered;
  71
  72 /* from module.c */
  73 extern int read_pipe, write_pipe;
  74 extern HANDLE hReadPipe;
  75 extern pid_t dosmod_pid;
  76
  77 static void do_exception( int signal, CONTEXT86 *context )
  78 {
  79     EXCEPTION_RECORD rec;
  80     if ((signal == SIGTRAP) || (signal == SIGHUP))
  81     {
  82         rec.ExceptionCode  = EXCEPTION_BREAKPOINT;
  83         rec.ExceptionFlags = EXCEPTION_CONTINUABLE;
  84     }
  85     else
  86     {
  87         rec.ExceptionCode  = EXCEPTION_ILLEGAL_INSTRUCTION;  /* generic error */
  88         rec.ExceptionFlags = EH_NONCONTINUABLE;
  89     }
  90     rec.ExceptionRecord  = NULL;
  91     rec.ExceptionAddress = (LPVOID)context->Eip;
  92     rec.NumberParameters = 0;
  93     EXC_RtlRaiseException( &rec, context );
  94 }
  95
  96 static void DOSVM_Dump( int fn, int sig, struct vm86plus_struct*VM86 )
  97 {
  98  BYTE*inst;
  99  int x;
 100
 101  switch (VM86_TYPE(fn)) {
 102   case VM86_SIGNAL:
 103    printf("Trapped signal %d\n",sig); break;
 104   case VM86_UNKNOWN:
 105    printf("Trapped unhandled GPF\n"); break;
 106   case VM86_INTx:
 107    printf("Trapped INT %02x\n",VM86_ARG(fn)); break;
 108   case VM86_STI:
 109    printf("Trapped STI\n"); break;
 110   case VM86_PICRETURN:
 111    printf("Trapped due to pending PIC request\n"); break;
 112   case VM86_TRAP:
 113    printf("Trapped debug request\n"); break;
 114   default:
 115    printf("Trapped unknown VM86 type %d arg %d\n",VM86_TYPE(fn),VM86_ARG(fn)); break;
 116  }
 117 #define REGS VM86->regs
 118  fprintf(stderr,"AX=%04lX CX=%04lX DX=%04lX BX=%04lX\n",REGS.eax,REGS.ecx,REGS.edx,REGS.ebx);
 119  fprintf(stderr,"SI=%04lX DI=%04lX SP=%04lX BP=%04lX\n",REGS.esi,REGS.edi,REGS.esp,REGS.ebp);
 120  fprintf(stderr,"CS=%04X DS=%04X ES=%04X SS=%04X\n",REGS.cs,REGS.ds,REGS.es,REGS.ss);
 121  fprintf(stderr,"IP=%04lX EFLAGS=%08lX\n",REGS.eip,REGS.eflags);
 122
 123  inst = PTR_REAL_TO_LIN( REGS.cs, REGS.eip );
 124 #undef REGS
 125  printf("Opcodes:");
 126  for (x=0; x<8; x++) printf(" %02x",inst[x]);
 127  printf("\n");
 128 }
 129
 130 static int DOSVM_SimulateInt( int vect, CONTEXT86 *context, BOOL inwine )
 131 {
 132   FARPROC16 handler=INT_GetRMHandler(vect);
 133
 134   /* check for our real-mode hooks */
 135   if (vect==0x31) {
 136     if (context->SegCs==DOSMEM_wrap_seg) {
 137       /* exit from real-mode wrapper */
 138       return -1;
 139     }
 140     /* we could probably move some other dodgy stuff here too from dpmi.c */
 141   }
 142   /* check if the call is from our fake BIOS interrupt stubs */
 143   if ((context->SegCs==0xf000) && !inwine) {
 144     if (vect != (context->Eip/4)) {
 145       TRACE_(int)("something fishy going on here (interrupt stub is %02lx)\n", context->Eip/4);
 146     }
 147     TRACE_(int)("builtin interrupt %02x has been branched to\n", vect);
 148     INT_RealModeInterrupt(vect, context);
 149   }
 150   /* check if the call goes to an unhooked interrupt */
 151   else if (SELECTOROF(handler)==0xf000) {
 152     /* if so, call it directly */
 153     TRACE_(int)("builtin interrupt %02x has been invoked (through vector %02x)\n", OFFSETOF(handler)/4, vect);
 154     INT_RealModeInterrupt(OFFSETOF(handler)/4, context);
 155   }
 156   /* the interrupt is hooked, simulate interrupt in DOS space */
 157   else {
 158     WORD*stack= PTR_REAL_TO_LIN( context->SegSs, context->Esp );
 159     WORD flag=LOWORD(context->EFlags);
 160
 161     if (IF_ENABLED(context)) flag|=IF_MASK;
 162     else flag&=~IF_MASK;
 163
 164     *(--stack)=flag;
 165     *(--stack)=context->SegCs;
 166     *(--stack)=LOWORD(context->Eip);
 167     context->Esp-=6;
 168     context->SegCs=SELECTOROF(handler);
 169     context->Eip=OFFSETOF(handler);
 170     IF_CLR(context);
 171   }
 172   return 0;
 173 }
 174
 175 #define SHOULD_PEND(x) \
 176   (x && ((!current_event) || (x->priority < current_event->priority)))
 177
 178 static void DOSVM_SendQueuedEvent(CONTEXT86 *context)
 179 {
 180   LPDOSEVENT event = pending_event;
 181
 182   if (SHOULD_PEND(event)) {
 183     /* remove from "pending" list */
 184     pending_event = event->next;
 185     /* process event */
 186     if (event->irq>=0) {
 187       /* it's an IRQ, move it to "current" list */
 188       event->next = current_event;
 189       current_event = event;
 190       TRACE_(int)("dispatching IRQ %d\n",event->irq);
 191       /* note that if DOSVM_SimulateInt calls an internal interrupt directly,
 192        * current_event might be cleared (and event freed) in this very call! */
 193       DOSVM_SimulateInt((event->irq<8)?(event->irq+8):(event->irq-8+0x70),context,TRUE);
 194     } else {
 195       /* callback event */
 196       TRACE_(int)("dispatching callback event\n");
 197       (*event->relay)(context,event->data);
 198       free(event);
 199     }
 200   }
 201   if (!SHOULD_PEND(pending_event)) {
 202     TRACE_(int)("clearing Pending flag\n");
 203     CLR_PEND(context);
 204   }
 205 }
 206
 207 static void DOSVM_SendQueuedEvents(CONTEXT86 *context)
 208 {
 209   /* we will send all queued events as long as interrupts are enabled,
 210    * but IRQ events will disable interrupts again */
 211   while (IS_PEND(context) && IF_ENABLED(context))
 212     DOSVM_SendQueuedEvent(context);
 213 }
 214
 215 void DOSVM_QueueEvent( int irq, int priority, void (*relay)(CONTEXT86*,void*), void *data)
 216 {
 217   LPDOSEVENT event, cur, prev;
 218
 219   if (entered) {
 220     event = malloc(sizeof(DOSEVENT));
 221     if (!event) {
 222       ERR_(int)("out of memory allocating event entry\n");
 223       return;
 224     }
 225     event->irq = irq; event->priority = priority;
 226     event->relay = relay; event->data = data;
 227
 228     /* insert event into linked list, in order *after*
 229      * all earlier events of higher or equal priority */
 230     cur = pending_event; prev = NULL;
 231     while (cur && cur->priority<=priority) {
 232       prev = cur;
 233       cur = cur->next;
 234     }
 235     event->next = cur;
 236     if (prev) prev->next = event;
 237     else pending_event = event;
 238
 239     /* get dosmod's attention to the new event, if necessary */
 240     if (!sig_sent) {
 241       TRACE_(int)("new event queued, signalling dosmod\n");
 242       kill(dosmod_pid,SIGUSR2);
 243       sig_sent++;
 244     } else {
 245       TRACE_(int)("new event queued\n");
 246     }
 247   } else {
 248     /* DOS subsystem not running */
 249     /* (this probably means that we're running a win16 app
 250      *  which uses DPMI to thunk down to DOS services) */
 251     if (irq<0) {
 252       /* callback event, perform it with dummy context */
 253       CONTEXT86 context;
 254       memset(&context,0,sizeof(context));
 255       (*relay)(&context,data);
 256     } else {
 257       ERR_(int)("IRQ without DOS task: should not happen");
 258     }
 259   }
 260 }
 261
 262 #define CV do { CP(eax,Eax); CP(ecx,Ecx); CP(edx,Edx); CP(ebx,Ebx); \
 263            CP(esi,Esi); CP(edi,Edi); CP(esp,Esp); CP(ebp,Ebp); \
 264            CP(cs,SegCs); CP(ds,SegDs); CP(es,SegEs); \
 265            CP(ss,SegSs); CP(fs,SegFs); CP(gs,SegGs); \
 266            CP(eip,Eip); CP(eflags,EFlags); } while(0)
 267
 268 static int DOSVM_Process( int fn, int sig, struct vm86plus_struct*VM86 )
 269 {
 270  CONTEXT86 context;
 271  int ret=0;
 272
 273 #define CP(x,y) context.y = VM86->regs.x
 274   CV;
 275 #undef CP
 276  if (VM86_TYPE(fn)==VM86_UNKNOWN) {
 277   ret=INSTR_EmulateInstruction(&context);
 278 #define CP(x,y) VM86->regs.x = context.y
 279   CV;
 280 #undef CP
 281   if (ret) return 0;
 282   ret=0;
 283  }
 284 #ifdef TRY_PICRETURN
 285  if (VM86->vm86plus.force_return_for_pic) {
 286    SET_PEND(&context);
 287  }
 288 #else
 289  /* linux doesn't preserve pending flag on return */
 290  if (SHOULD_PEND(pending_event)) {
 291    SET_PEND(&context);
 292  }
 293 #endif
 294
 295  switch (VM86_TYPE(fn)) {
 296   case VM86_SIGNAL:
 297    TRACE_(int)("DOS module caught signal %d\n",sig);
 298    if ((sig==SIGALRM) || (sig==SIGUSR2)) {
 299      if (sig==SIGALRM) {
 300        sig_sent++;
 301        DOSVM_QueueEvent(0,DOS_PRIORITY_REALTIME,NULL,NULL);
 302      }
 303      if (pending_event) {
 304        TRACE_(int)("setting Pending flag, interrupts are currently %s\n",
 305                  IF_ENABLED(&context) ? "enabled" : "disabled");
 306        SET_PEND(&context);
 307        DOSVM_SendQueuedEvents(&context);
 308      } else {
 309        TRACE_(int)("no events are pending, clearing Pending flag\n");
 310        CLR_PEND(&context);
 311      }
 312      sig_sent--;
 313    }
 314    else if ((sig==SIGHUP) || (sig==SIGILL) || (sig==SIGSEGV)) {
 315        do_exception( sig, &context );
 316    } else {
 317     DOSVM_Dump(fn,sig,VM86);
 318     ret=-1;
 319    }
 320    break;
 321   case VM86_UNKNOWN: /* unhandled GPF */
 322    DOSVM_Dump(fn,sig,VM86);
 323    do_exception( SIGSEGV, &context );
 324    break;
 325   case VM86_INTx:
 326    if (TRACE_ON(relay))
 327     DPRINTF("Call DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
 328    ret=DOSVM_SimulateInt(VM86_ARG(fn),&context,FALSE);
 329    if (TRACE_ON(relay))
 330     DPRINTF("Ret  DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
 331    break;
 332   case VM86_STI:
 333     IF_SET(&context);
 334   /* case VM86_PICRETURN: */
 335     TRACE_(int)("DOS task enabled interrupts %s events pending, sending events\n", IS_PEND(&context)?"with":"without");
 336     DOSVM_SendQueuedEvents(&context);
 337     break;
 338   case VM86_TRAP:
 339    do_exception( SIGTRAP, &context );
 340    break;
 341   default:
 342    DOSVM_Dump(fn,sig,VM86);
 343    ret=-1;
 344  }
 345
 346 #define CP(x,y) VM86->regs.x = context.y
 347  CV;
 348 #undef CP
 349 #ifdef TRY_PICRETURN
 350  VM86->vm86plus.force_return_for_pic = IS_PEND(&context) ? 1 : 0;
 351  CLR_PEND(&context);
 352 #endif
 353  return ret;
 354 }
 355
 356 static void DOSVM_ProcessConsole(void)
 357 {
 358   INPUT_RECORD msg;
 359   DWORD res;
 360   BYTE scan;
 361
 362   if (ReadConsoleInputA(GetStdHandle(STD_INPUT_HANDLE),&msg,1,&res)) {
 363     switch (msg.EventType) {
 364     case KEY_EVENT:
 365       scan = msg.Event.KeyEvent.wVirtualScanCode;
 366       if (!msg.Event.KeyEvent.bKeyDown) scan |= 0x80;
 367
 368       /* check whether extended bit is set,
 369        * and if so, queue the extension prefix */
 370       if (msg.Event.KeyEvent.dwControlKeyState & ENHANCED_KEY) {
 371         INT_Int09SendScan(0xE0,0);
 372       }
 373       INT_Int09SendScan(scan,msg.Event.KeyEvent.uChar.AsciiChar);
 374       break;
 375     default:
 376       FIXME_(int)("unhandled console event: %d\n", msg.EventType);
 377     }
 378   }
 379 }
 380
 381 static void DOSVM_ProcessMessage(MSG *msg)
 382 {
 383   BYTE scan = 0;
 384
 385   TRACE_(int)("got message %04x, wparam=%08x, lparam=%08lx\n",msg->message,msg->wParam,msg->lParam);
 386   if ((msg->message>=WM_MOUSEFIRST)&&
 387       (msg->message<=WM_MOUSELAST)) {
 388     INT_Int33Message(msg->message,msg->wParam,msg->lParam);
 389   } else {
 390     switch (msg->message) {
 391     case WM_KEYUP:
 392       scan = 0x80;
 393     case WM_KEYDOWN:
 394       scan |= (msg->lParam >> 16) & 0x7f;
 395
 396       /* check whether extended bit is set,
 397        * and if so, queue the extension prefix */
 398       if (msg->lParam & 0x1000000) {
 399         /* FIXME: some keys (function keys) have
 400          * extended bit set even when they shouldn't,
 401          * should check for them */
 402         INT_Int09SendScan(0xE0,0);
 403       }
 404       INT_Int09SendScan(scan,0);
 405       break;
 406     }
 407   }
 408 }
 409
 410 void DOSVM_Wait( int read_pipe, HANDLE hObject )
 411 {
 412   MSG msg;
 413   DWORD waitret;
 414   HANDLE objs[2];
 415   int objc;
 416   BOOL got_msg = FALSE;
 417
 418   objs[0]=GetStdHandle(STD_INPUT_HANDLE);
 419   objs[1]=hObject;
 420   objc=hObject?2:1;
 421   do {
 422     /* check for messages (waste time before the response check below) */
 423     while (Callout.PeekMessageA(&msg,0,0,0,PM_REMOVE|PM_NOYIELD)) {
 424       /* got a message */
 425       DOSVM_ProcessMessage(&msg);
 426       /* we don't need a TranslateMessage here */
 427       Callout.DispatchMessageA(&msg);
 428       got_msg = TRUE;
 429     }
 430     if (!got_msg) {
 431       /* check for console input */
 432       INPUT_RECORD msg;
 433       DWORD num;
 434       if (PeekConsoleInputA(objs[0],&msg,1,&num) && num) {
 435         DOSVM_ProcessConsole();
 436         got_msg = TRUE;
 437       }
 438     }
 439     if (read_pipe == -1) {
 440       if (got_msg) break;
 441     } else {
 442       fd_set readfds;
 443       struct timeval timeout={0,0};
 444       /* quick check for response from dosmod
 445        * (faster than doing the full blocking wait, if data already available) */
 446       FD_ZERO(&readfds); FD_SET(read_pipe,&readfds);
 447       if (select(read_pipe+1,&readfds,NULL,NULL,&timeout)>0)
 448         break;
 449     }
 450     /* nothing yet, block while waiting for something to do */
 451     waitret=Callout.MsgWaitForMultipleObjects(objc,objs,FALSE,INFINITE,QS_ALLINPUT);
 452     if (waitret==(DWORD)-1) {
 453       ERR_(module)("dosvm wait error=%ld\n",GetLastError());
 454     }
 455     if ((read_pipe != -1) && hObject) {
 456       if (waitret==(WAIT_OBJECT_0+1)) break;
 457     }
 458     if (waitret==WAIT_OBJECT_0) {
 459       DOSVM_ProcessConsole();
 460     }
 461   } while (TRUE);
 462 }
 463
 464 int DOSVM_Enter( CONTEXT86 *context )
 465 {
 466  struct vm86plus_struct VM86;
 467  int stat,len,sig;
 468
 469  memset(&VM86, 0, sizeof(VM86));
 470 #define CP(x,y) VM86.regs.x = context->y
 471   CV;
 472 #undef CP
 473   if (VM86.regs.eflags & IF_MASK)
 474     VM86.regs.eflags |= VIF_MASK;
 475
 476  /* main exchange loop */
 477  entered++;
 478  do {
 479   TRACE_(module)("thread is: %lx\n",GetCurrentThreadId());
 480   stat = VM86_ENTER;
 481   errno = 0;
 482   /* transmit VM86 structure to dosmod task */
 483   if (write(write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 484    ERR_(module)("dosmod sync lost, errno=%d, fd=%d, pid=%d\n",errno,write_pipe,getpid());
 485    return -1;
 486   }
 487   if (write(write_pipe,&VM86,sizeof(VM86))!=sizeof(VM86)) {
 488    ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 489    return -1;
 490   }
 491   /* wait for response, doing other things in the meantime */
 492   DOSVM_Wait(read_pipe, hReadPipe);
 493   /* read response */
 494   while (1) {
 495     if ((len=read(read_pipe,&stat,sizeof(stat)))==sizeof(stat)) break;
 496     if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 497      WARN_(module)("rereading dosmod return code due to errno=%d, result=%d\n",errno,len);
 498      continue;
 499     }
 500     ERR_(module)("dosmod sync lost reading return code, errno=%d, result=%d\n",errno,len);
 501     return -1;
 502   }
 503   TRACE_(module)("dosmod return code=%d\n",stat);
 504   if (stat==DOSMOD_LEFTIDLE) {
 505     continue;
 506   }
 507   while (1) {
 508     if ((len=read(read_pipe,&VM86,sizeof(VM86)))==sizeof(VM86)) break;
 509     if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 510      WARN_(module)("rereading dosmod VM86 structure due to errno=%d, result=%d\n",errno,len);
 511      continue;
 512     }
 513     ERR_(module)("dosmod sync lost reading VM86 structure, errno=%d, result=%d\n",errno,len);
 514     return -1;
 515   }
 516   if ((stat&0xff)==DOSMOD_SIGNAL) {
 517     while (1) {
 518       if ((len=read(read_pipe,&sig,sizeof(sig)))==sizeof(sig)) break;
 519       if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 520         WARN_(module)("rereading dosmod signal due to errno=%d, result=%d\n",errno,len);
 521         continue;
 522       }
 523       ERR_(module)("dosmod sync lost reading signal, errno=%d, result=%d\n",errno,len);
 524       return -1;
 525     } while (0);
 526   } else sig=0;
 527   /* got response */
 528  } while (DOSVM_Process(stat,sig,&VM86)>=0);
 529  entered--;
 530
 531 #define CP(x,y) context->y = VM86.regs.x
 532   CV;
 533 #undef CP
 534  return 0;
 535 }
 536
 537 void DOSVM_PIC_ioport_out( WORD port, BYTE val)
 538 {
 539     LPDOSEVENT event;
 540
 541     if ((port==0x20) && (val==0x20)) {
 542       if (current_event) {
 543         /* EOI (End Of Interrupt) */
 544         TRACE_(int)("received EOI for current IRQ, clearing\n");
 545         event = current_event;
 546         current_event = event->next;
 547         if (event->relay)
 548         (*event->relay)(NULL,event->data);
 549         free(event);
 550
 551         if (pending_event &&
 552             !sig_sent) {
 553           /* another event is pending, which we should probably
 554            * be able to process now, so tell dosmod about it */
 555           TRACE_(int)("another event pending, signalling dosmod\n");
 556           kill(dosmod_pid,SIGUSR2);
 557           sig_sent++;
 558         }
 559       } else {
 560         WARN_(int)("EOI without active IRQ\n");
 561       }
 562     } else {
 563       FIXME_(int)("unrecognized PIC command %02x\n",val);
 564     }
 565 }
 566
 567 void DOSVM_SetTimer( unsigned ticks )
 568 {
 569   int stat=DOSMOD_SET_TIMER;
 570   struct timeval tim;
 571
 572   if (MZ_Current()) {
 573     /* the PC clocks ticks at 1193180 Hz */
 574     tim.tv_sec=0;
 575     tim.tv_usec=MulDiv(ticks,1000000,1193180);
 576     /* sanity check */
 577     if (!tim.tv_usec) tim.tv_usec=1;
 578
 579     if (write(write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 580       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 581       return;
 582     }
 583     if (write(write_pipe,&tim,sizeof(tim))!=sizeof(tim)) {
 584       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 585       return;
 586     }
 587     /* there's no return */
 588   }
 589 }
 590
 591 unsigned DOSVM_GetTimer( void )
 592 {
 593   int stat=DOSMOD_GET_TIMER;
 594   struct timeval tim;
 595
 596   if (MZ_Current()) {
 597     if (write(write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 598       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 599       return 0;
 600     }
 601     /* read response */
 602     while (1) {
 603       if (read(read_pipe,&tim,sizeof(tim))==sizeof(tim)) break;
 604       if ((errno==EINTR)||(errno==EAGAIN)) continue;
 605       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 606       return 0;
 607     }
 608     return MulDiv(tim.tv_usec,1193180,1000000);
 609   }
 610   return 0;
 611 }
 612
 613 #else /* !MZ_SUPPORTED */
 614
 615 int DOSVM_Enter( CONTEXT86 *context )
 616 {
 617  ERR_(module)("DOS realmode not supported on this architecture!\n");
 618  return -1;
 619 }
 620
 621 void DOSVM_Wait( int read_pipe, HANDLE hObject) {}
 622 void DOSVM_PIC_ioport_out( WORD port, BYTE val) {}
 623 void DOSVM_SetTimer( unsigned ticks ) {}
 624 unsigned DOSVM_GetTimer( void ) { return 0; }
 625 void DOSVM_QueueEvent( int irq, int priority, void (*relay)(CONTEXT86*,void*), void *data)
 626 {
 627   if (irq<0) {
 628     /* callback event, perform it with dummy context */
 629     CONTEXT86 context;
 630     memset(&context,0,sizeof(context));
 631     (*relay)(&context,data);
 632   } else {
 633     ERR_(int)("IRQ without DOS task: should not happen");
 634   }
 635 }
 636
 637 #endif