qemu-timer.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "sysemu/sysemu.h"
  26 #include "monitor/monitor.h"
  27 #include "ui/console.h"
  28
  29 #include "hw/hw.h"
  30
  31 #include "qemu/timer.h"
  32 #ifdef CONFIG_POSIX
  33 #include <pthread.h>
  34 #endif
  35
  36 #ifdef _WIN32
  37 #include <mmsystem.h>
  38 #endif
  39
  40 /***********************************************************/
  41 /* timers */
  42
  43 struct QEMUClock {
  44     QEMUTimer *active_timers;
  45
  46     NotifierList reset_notifiers;
  47     int64_t last;
  48
  49     int type;
  50     bool enabled;
  51 };
  52
  53 struct QEMUTimer {
  54     int64_t expire_time;        /* in nanoseconds */
  55     QEMUClock *clock;
  56     QEMUTimerCB *cb;
  57     void *opaque;
  58     QEMUTimer *next;
  59     int scale;
  60 };
  61
  62 struct qemu_alarm_timer {
  63     char const *name;
  64     int (*start)(struct qemu_alarm_timer *t);
  65     void (*stop)(struct qemu_alarm_timer *t);
  66     void (*rearm)(struct qemu_alarm_timer *t, int64_t nearest_delta_ns);
  67 #if defined(__linux__)
  68     timer_t timer;
  69     int fd;
  70 #elif defined(_WIN32)
  71     HANDLE timer;
  72 #endif
  73     bool expired;
  74     bool pending;
  75 };
  76
  77 static struct qemu_alarm_timer *alarm_timer;
  78
  79 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  80 {
  81     return timer_head && (timer_head->expire_time <= current_time);
  82 }
  83
  84 static int64_t qemu_next_alarm_deadline(void)
  85 {
  86     int64_t delta = INT64_MAX;
  87     int64_t rtdelta;
  88
  89     if (!use_icount && vm_clock->enabled && vm_clock->active_timers) {
  90         delta = vm_clock->active_timers->expire_time -
  91                      qemu_get_clock_ns(vm_clock);
  92     }
  93     if (host_clock->enabled && host_clock->active_timers) {
  94         int64_t hdelta = host_clock->active_timers->expire_time -
  95                  qemu_get_clock_ns(host_clock);
  96         if (hdelta < delta) {
  97             delta = hdelta;
  98         }
  99     }
 100     if (rt_clock->enabled && rt_clock->active_timers) {
 101         rtdelta = (rt_clock->active_timers->expire_time -
 102                  qemu_get_clock_ns(rt_clock));
 103         if (rtdelta < delta) {
 104             delta = rtdelta;
 105         }
 106     }
 107
 108     return delta;
 109 }
 110
 111 static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
 112 {
 113     int64_t nearest_delta_ns = qemu_next_alarm_deadline();
 114     if (nearest_delta_ns < INT64_MAX) {
 115         t->rearm(t, nearest_delta_ns);
 116     }
 117 }
 118
 119 /* TODO: MIN_TIMER_REARM_NS should be optimized */
 120 #define MIN_TIMER_REARM_NS 250000
 121
 122 #ifdef _WIN32
 123
 124 static int mm_start_timer(struct qemu_alarm_timer *t);
 125 static void mm_stop_timer(struct qemu_alarm_timer *t);
 126 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 127
 128 static int win32_start_timer(struct qemu_alarm_timer *t);
 129 static void win32_stop_timer(struct qemu_alarm_timer *t);
 130 static void win32_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 131
 132 #else
 133
 134 static int unix_start_timer(struct qemu_alarm_timer *t);
 135 static void unix_stop_timer(struct qemu_alarm_timer *t);
 136 static void unix_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 137
 138 #ifdef __linux__
 139
 140 static int dynticks_start_timer(struct qemu_alarm_timer *t);
 141 static void dynticks_stop_timer(struct qemu_alarm_timer *t);
 142 static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 143
 144 #endif /* __linux__ */
 145
 146 #endif /* _WIN32 */
 147
 148 static struct qemu_alarm_timer alarm_timers[] = {
 149 #ifndef _WIN32
 150 #ifdef __linux__
 151     {"dynticks", dynticks_start_timer,
 152      dynticks_stop_timer, dynticks_rearm_timer},
 153 #endif
 154     {"unix", unix_start_timer, unix_stop_timer, unix_rearm_timer},
 155 #else
 156     {"mmtimer", mm_start_timer, mm_stop_timer, mm_rearm_timer},
 157     {"dynticks", win32_start_timer, win32_stop_timer, win32_rearm_timer},
 158 #endif
 159     {NULL, }
 160 };
 161
 162 static void show_available_alarms(void)
 163 {
 164     int i;
 165
 166     printf("Available alarm timers, in order of precedence:\n");
 167     for (i = 0; alarm_timers[i].name; i++)
 168         printf("%s\n", alarm_timers[i].name);
 169 }
 170
 171 void configure_alarms(char const *opt)
 172 {
 173     int i;
 174     int cur = 0;
 175     int count = ARRAY_SIZE(alarm_timers) - 1;
 176     char *arg;
 177     char *name;
 178     struct qemu_alarm_timer tmp;
 179
 180     if (is_help_option(opt)) {
 181         show_available_alarms();
 182         exit(0);
 183     }
 184
 185     arg = g_strdup(opt);
 186
 187     /* Reorder the array */
 188     name = strtok(arg, ",");
 189     while (name) {
 190         for (i = 0; i < count && alarm_timers[i].name; i++) {
 191             if (!strcmp(alarm_timers[i].name, name))
 192                 break;
 193         }
 194
 195         if (i == count) {
 196             fprintf(stderr, "Unknown clock %s\n", name);
 197             goto next;
 198         }
 199
 200         if (i < cur)
 201             /* Ignore */
 202             goto next;
 203
 204         /* Swap */
 205         tmp = alarm_timers[i];
 206         alarm_timers[i] = alarm_timers[cur];
 207         alarm_timers[cur] = tmp;
 208
 209         cur++;
 210 next:
 211         name = strtok(NULL, ",");
 212     }
 213
 214     g_free(arg);
 215
 216     if (cur) {
 217         /* Disable remaining timers */
 218         for (i = cur; i < count; i++)
 219             alarm_timers[i].name = NULL;
 220     } else {
 221         show_available_alarms();
 222         exit(1);
 223     }
 224 }
 225
 226 QEMUClock *rt_clock;
 227 QEMUClock *vm_clock;
 228 QEMUClock *host_clock;
 229
 230 static QEMUClock *qemu_clock_new(int type)
 231 {
 232     QEMUClock *clock;
 233
 234     clock = g_malloc0(sizeof(QEMUClock));
 235     clock->type = type;
 236     clock->enabled = true;
 237     clock->last = INT64_MIN;
 238     notifier_list_init(&clock->reset_notifiers);
 239     return clock;
 240 }
 241
 242 void qemu_clock_enable(QEMUClock *clock, bool enabled)
 243 {
 244     bool old = clock->enabled;
 245     clock->enabled = enabled;
 246     if (enabled && !old) {
 247         qemu_rearm_alarm_timer(alarm_timer);
 248     }
 249 }
 250
 251 int64_t qemu_clock_has_timers(QEMUClock *clock)
 252 {
 253     return !!clock->active_timers;
 254 }
 255
 256 int64_t qemu_clock_expired(QEMUClock *clock)
 257 {
 258     return (clock->active_timers &&
 259             clock->active_timers->expire_time < qemu_get_clock_ns(clock));
 260 }
 261
 262 int64_t qemu_clock_deadline(QEMUClock *clock)
 263 {
 264     /* To avoid problems with overflow limit this to 2^32.  */
 265     int64_t delta = INT32_MAX;
 266
 267     if (clock->active_timers) {
 268         delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 269     }
 270     if (delta < 0) {
 271         delta = 0;
 272     }
 273     return delta;
 274 }
 275
 276 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
 277                           QEMUTimerCB *cb, void *opaque)
 278 {
 279     QEMUTimer *ts;
 280
 281     ts = g_malloc0(sizeof(QEMUTimer));
 282     ts->clock = clock;
 283     ts->cb = cb;
 284     ts->opaque = opaque;
 285     ts->scale = scale;
 286     return ts;
 287 }
 288
 289 void qemu_free_timer(QEMUTimer *ts)
 290 {
 291     g_free(ts);
 292 }
 293
 294 /* stop a timer, but do not dealloc it */
 295 void qemu_del_timer(QEMUTimer *ts)
 296 {
 297     QEMUTimer **pt, *t;
 298
 299     /* NOTE: this code must be signal safe because
 300        timer_expired() can be called from a signal. */
 301     pt = &ts->clock->active_timers;
 302     for(;;) {
 303         t = *pt;
 304         if (!t)
 305             break;
 306         if (t == ts) {
 307             *pt = t->next;
 308             break;
 309         }
 310         pt = &t->next;
 311     }
 312 }
 313
 314 /* modify the current timer so that it will be fired when current_time
 315    >= expire_time. The corresponding callback will be called. */
 316 void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
 317 {
 318     QEMUTimer **pt, *t;
 319
 320     qemu_del_timer(ts);
 321
 322     /* add the timer in the sorted list */
 323     /* NOTE: this code must be signal safe because
 324        timer_expired() can be called from a signal. */
 325     pt = &ts->clock->active_timers;
 326     for(;;) {
 327         t = *pt;
 328         if (!timer_expired_ns(t, expire_time)) {
 329             break;
 330         }
 331         pt = &t->next;
 332     }
 333     ts->expire_time = expire_time;
 334     ts->next = *pt;
 335     *pt = ts;
 336
 337     /* Rearm if necessary  */
 338     if (pt == &ts->clock->active_timers) {
 339         if (!alarm_timer->pending) {
 340             qemu_rearm_alarm_timer(alarm_timer);
 341         }
 342         /* Interrupt execution to force deadline recalculation.  */
 343         qemu_clock_warp(ts->clock);
 344         if (use_icount) {
 345             qemu_notify_event();
 346         }
 347     }
 348 }
 349
 350 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 351 {
 352     qemu_mod_timer_ns(ts, expire_time * ts->scale);
 353 }
 354
 355 bool timer_pending(QEMUTimer *ts)
 356 {
 357     QEMUTimer *t;
 358     for (t = ts->clock->active_timers; t != NULL; t = t->next) {
 359         if (t == ts) {
 360             return true;
 361         }
 362     }
 363     return false;
 364 }
 365
 366 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 367 {
 368     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 369 }
 370
 371 void qemu_run_timers(QEMUClock *clock)
 372 {
 373     QEMUTimer *ts;
 374     int64_t current_time;
 375
 376     if (!clock->enabled)
 377         return;
 378
 379     current_time = qemu_get_clock_ns(clock);
 380     for(;;) {
 381         ts = clock->active_timers;
 382         if (!timer_expired_ns(ts, current_time)) {
 383             break;
 384         }
 385         /* remove timer from the list before calling the callback */
 386         clock->active_timers = ts->next;
 387         ts->next = NULL;
 388
 389         /* run the callback (the timer list can be modified) */
 390         ts->cb(ts->opaque);
 391     }
 392 }
 393
 394 int64_t qemu_get_clock_ns(QEMUClock *clock)
 395 {
 396     int64_t now, last;
 397
 398     switch(clock->type) {
 399     case QEMU_CLOCK_REALTIME:
 400         return get_clock();
 401     default:
 402     case QEMU_CLOCK_VIRTUAL:
 403         if (use_icount) {
 404             return cpu_get_icount();
 405         } else {
 406             return cpu_get_clock();
 407         }
 408     case QEMU_CLOCK_HOST:
 409         now = get_clock_realtime();
 410         last = clock->last;
 411         clock->last = now;
 412         if (now < last) {
 413             notifier_list_notify(&clock->reset_notifiers, &now);
 414         }
 415         return now;
 416     }
 417 }
 418
 419 void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 420 {
 421     notifier_list_add(&clock->reset_notifiers, notifier);
 422 }
 423
 424 void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 425 {
 426     notifier_remove(notifier);
 427 }
 428
 429 void init_clocks(void)
 430 {
 431     if (!rt_clock) {
 432         rt_clock = qemu_clock_new(QEMU_CLOCK_REALTIME);
 433         vm_clock = qemu_clock_new(QEMU_CLOCK_VIRTUAL);
 434         host_clock = qemu_clock_new(QEMU_CLOCK_HOST);
 435     }
 436 }
 437
 438 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 439 {
 440     return timer_pending(ts) ? ts->expire_time : -1;
 441 }
 442
 443 void qemu_run_all_timers(void)
 444 {
 445     alarm_timer->pending = false;
 446
 447     /* vm time timers */
 448     qemu_run_timers(vm_clock);
 449     qemu_run_timers(rt_clock);
 450     qemu_run_timers(host_clock);
 451
 452     /* rearm timer, if not periodic */
 453     if (alarm_timer->expired) {
 454         alarm_timer->expired = false;
 455         qemu_rearm_alarm_timer(alarm_timer);
 456     }
 457 }
 458
 459 #ifdef _WIN32
 460 static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
 461 #else
 462 static void host_alarm_handler(int host_signum)
 463 #endif
 464 {
 465     struct qemu_alarm_timer *t = alarm_timer;
 466     if (!t)
 467         return;
 468
 469     t->expired = true;
 470     t->pending = true;
 471     qemu_notify_event();
 472 }
 473
 474 #if defined(__linux__)
 475
 476 #include "qemu/compatfd.h"
 477
 478 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 479 {
 480     struct sigevent ev;
 481     timer_t host_timer;
 482     struct sigaction act;
 483
 484     sigfillset(&act.sa_mask);
 485     act.sa_flags = 0;
 486     act.sa_handler = host_alarm_handler;
 487
 488     sigaction(SIGALRM, &act, NULL);
 489
 490     /*
 491      * Initialize ev struct to 0 to avoid valgrind complaining
 492      * about uninitialized data in timer_create call
 493      */
 494     memset(&ev, 0, sizeof(ev));
 495     ev.sigev_value.sival_int = 0;
 496     ev.sigev_notify = SIGEV_SIGNAL;
 497 #ifdef CONFIG_SIGEV_THREAD_ID
 498     if (qemu_signalfd_available()) {
 499         ev.sigev_notify = SIGEV_THREAD_ID;
 500         ev._sigev_un._tid = qemu_get_thread_id();
 501     }
 502 #endif /* CONFIG_SIGEV_THREAD_ID */
 503     ev.sigev_signo = SIGALRM;
 504
 505     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 506         perror("timer_create");
 507         return -1;
 508     }
 509
 510     t->timer = host_timer;
 511
 512     return 0;
 513 }
 514
 515 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 516 {
 517     timer_t host_timer = t->timer;
 518
 519     timer_delete(host_timer);
 520 }
 521
 522 static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
 523                                  int64_t nearest_delta_ns)
 524 {
 525     timer_t host_timer = t->timer;
 526     struct itimerspec timeout;
 527     int64_t current_ns;
 528
 529     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 530         nearest_delta_ns = MIN_TIMER_REARM_NS;
 531
 532     /* check whether a timer is already running */
 533     if (timer_gettime(host_timer, &timeout)) {
 534         perror("gettime");
 535         fprintf(stderr, "Internal timer error: aborting\n");
 536         exit(1);
 537     }
 538     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 539     if (current_ns && current_ns <= nearest_delta_ns)
 540         return;
 541
 542     timeout.it_interval.tv_sec = 0;
 543     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 544     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 545     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 546     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 547         perror("settime");
 548         fprintf(stderr, "Internal timer error: aborting\n");
 549         exit(1);
 550     }
 551 }
 552
 553 #endif /* defined(__linux__) */
 554
 555 #if !defined(_WIN32)
 556
 557 static int unix_start_timer(struct qemu_alarm_timer *t)
 558 {
 559     struct sigaction act;
 560
 561     /* timer signal */
 562     sigfillset(&act.sa_mask);
 563     act.sa_flags = 0;
 564     act.sa_handler = host_alarm_handler;
 565
 566     sigaction(SIGALRM, &act, NULL);
 567     return 0;
 568 }
 569
 570 static void unix_rearm_timer(struct qemu_alarm_timer *t,
 571                              int64_t nearest_delta_ns)
 572 {
 573     struct itimerval itv;
 574     int err;
 575
 576     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 577         nearest_delta_ns = MIN_TIMER_REARM_NS;
 578
 579     itv.it_interval.tv_sec = 0;
 580     itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
 581     itv.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 582     itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
 583     err = setitimer(ITIMER_REAL, &itv, NULL);
 584     if (err) {
 585         perror("setitimer");
 586         fprintf(stderr, "Internal timer error: aborting\n");
 587         exit(1);
 588     }
 589 }
 590
 591 static void unix_stop_timer(struct qemu_alarm_timer *t)
 592 {
 593     struct itimerval itv;
 594
 595     memset(&itv, 0, sizeof(itv));
 596     setitimer(ITIMER_REAL, &itv, NULL);
 597 }
 598
 599 #endif /* !defined(_WIN32) */
 600
 601
 602 #ifdef _WIN32
 603
 604 static MMRESULT mm_timer;
 605 static TIMECAPS mm_tc;
 606
 607 static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
 608                                       DWORD_PTR dwUser, DWORD_PTR dw1,
 609                                       DWORD_PTR dw2)
 610 {
 611     struct qemu_alarm_timer *t = alarm_timer;
 612     if (!t) {
 613         return;
 614     }
 615     t->expired = true;
 616     t->pending = true;
 617     qemu_notify_event();
 618 }
 619
 620 static int mm_start_timer(struct qemu_alarm_timer *t)
 621 {
 622     timeGetDevCaps(&mm_tc, sizeof(mm_tc));
 623     return 0;
 624 }
 625
 626 static void mm_stop_timer(struct qemu_alarm_timer *t)
 627 {
 628     if (mm_timer) {
 629         timeKillEvent(mm_timer);
 630     }
 631 }
 632
 633 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
 634 {
 635     int64_t nearest_delta_ms = delta / 1000000;
 636     if (nearest_delta_ms < mm_tc.wPeriodMin) {
 637         nearest_delta_ms = mm_tc.wPeriodMin;
 638     } else if (nearest_delta_ms > mm_tc.wPeriodMax) {
 639         nearest_delta_ms = mm_tc.wPeriodMax;
 640     }
 641
 642     if (mm_timer) {
 643         timeKillEvent(mm_timer);
 644     }
 645     mm_timer = timeSetEvent((UINT)nearest_delta_ms,
 646                             mm_tc.wPeriodMin,
 647                             mm_alarm_handler,
 648                             (DWORD_PTR)t,
 649                             TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
 650
 651     if (!mm_timer) {
 652         fprintf(stderr, "Failed to re-arm win32 alarm timer\n");
 653         timeEndPeriod(mm_tc.wPeriodMin);
 654         exit(1);
 655     }
 656 }
 657
 658 static int win32_start_timer(struct qemu_alarm_timer *t)
 659 {
 660     HANDLE hTimer;
 661     BOOLEAN success;
 662
 663     /* If you call ChangeTimerQueueTimer on a one-shot timer (its period
 664        is zero) that has already expired, the timer is not updated.  Since
 665        creating a new timer is relatively expensive, set a bogus one-hour
 666        interval in the dynticks case.  */
 667     success = CreateTimerQueueTimer(&hTimer,
 668                           NULL,
 669                           host_alarm_handler,
 670                           t,
 671                           1,
 672                           3600000,
 673                           WT_EXECUTEINTIMERTHREAD);
 674
 675     if (!success) {
 676         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 677                 GetLastError());
 678         return -1;
 679     }
 680
 681     t->timer = hTimer;
 682     return 0;
 683 }
 684
 685 static void win32_stop_timer(struct qemu_alarm_timer *t)
 686 {
 687     HANDLE hTimer = t->timer;
 688
 689     if (hTimer) {
 690         DeleteTimerQueueTimer(NULL, hTimer, NULL);
 691     }
 692 }
 693
 694 static void win32_rearm_timer(struct qemu_alarm_timer *t,
 695                               int64_t nearest_delta_ns)
 696 {
 697     HANDLE hTimer = t->timer;
 698     int64_t nearest_delta_ms;
 699     BOOLEAN success;
 700
 701     nearest_delta_ms = nearest_delta_ns / 1000000;
 702     if (nearest_delta_ms < 1) {
 703         nearest_delta_ms = 1;
 704     }
 705     /* ULONG_MAX can be 32 bit */
 706     if (nearest_delta_ms > ULONG_MAX) {
 707         nearest_delta_ms = ULONG_MAX;
 708     }
 709     success = ChangeTimerQueueTimer(NULL,
 710                                     hTimer,
 711                                     (unsigned long) nearest_delta_ms,
 712                                     3600000);
 713
 714     if (!success) {
 715         fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
 716                 GetLastError());
 717         exit(-1);
 718     }
 719
 720 }
 721
 722 #endif /* _WIN32 */
 723
 724 static void quit_timers(void)
 725 {
 726     struct qemu_alarm_timer *t = alarm_timer;
 727     alarm_timer = NULL;
 728     t->stop(t);
 729 }
 730
 731 #ifdef CONFIG_POSIX
 732 static void reinit_timers(void)
 733 {
 734     struct qemu_alarm_timer *t = alarm_timer;
 735     t->stop(t);
 736     if (t->start(t)) {
 737         fprintf(stderr, "Internal timer error: aborting\n");
 738         exit(1);
 739     }
 740     qemu_rearm_alarm_timer(t);
 741 }
 742 #endif /* CONFIG_POSIX */
 743
 744 int init_timer_alarm(void)
 745 {
 746     struct qemu_alarm_timer *t = NULL;
 747     int i, err = -1;
 748
 749     if (alarm_timer) {
 750         return 0;
 751     }
 752
 753     for (i = 0; alarm_timers[i].name; i++) {
 754         t = &alarm_timers[i];
 755
 756         err = t->start(t);
 757         if (!err)
 758             break;
 759     }
 760
 761     if (err) {
 762         err = -ENOENT;
 763         goto fail;
 764     }
 765
 766     atexit(quit_timers);
 767 #ifdef CONFIG_POSIX
 768     pthread_atfork(NULL, NULL, reinit_timers);
 769 #endif
 770     alarm_timer = t;
 771     return 0;
 772
 773 fail:
 774     return err;
 775 }
 776