dotnet · jkotas · Feb 8, 2026 · Feb 7, 2026 · Feb 7, 2026 · Feb 7, 2026
diff --git a/eng/native/tryrun.browser.cmake b/eng/native/tryrun.browser.cmake
@@ -130,9 +130,6 @@ set(HAVE_CFSETSPEED 1 CACHE INTERNAL "")
 set(HAVE_CHMOD 1 CACHE INTERNAL "")
 set(HAVE_CLOCK_GETTIME_NSEC_NP "" CACHE INTERNAL "")
 set(HAVE_CLOCK_MONOTONIC_COARSE 1 CACHE INTERNAL "")
-set(HAVE_CLOCK_MONOTONIC_COMPILED TRUE CACHE INTERNAL "")
-set_cache_value(HAVE_CLOCK_MONOTONIC_EXITCODE 0)
-set(HAVE_CLOCK_MONOTONIC 1 CACHE INTERNAL "")
 set(HAVE_CLOCK_THREAD_CPUTIME_COMPILED TRUE CACHE INTERNAL "")
 set_cache_value(HAVE_CLOCK_THREAD_CPUTIME_EXITCODE 255)
 set(HAVE_CLOCK_THREAD_CPUTIME "" CACHE INTERNAL "")

diff --git a/eng/native/tryrun.cmake b/eng/native/tryrun.cmake
@@ -54,7 +54,6 @@ if(DARWIN AND NOT DEFINED ANDROID_BUILD)
     set_cache_value(HAVE_BROKEN_FIFO_KEVENT_EXITCODE 1)
     set_cache_value(HAVE_BROKEN_FIFO_SELECT_EXITCODE 1)
     set_cache_value(HAVE_CLOCK_MONOTONIC_COARSE_EXITCODE 1)
-    set_cache_value(HAVE_CLOCK_MONOTONIC_EXITCODE 0)
     set_cache_value(HAVE_CLOCK_REALTIME_EXITCODE 0)
     set_cache_value(HAVE_CLOCK_THREAD_CPUTIME_EXITCODE 0)
     set_cache_value(HAVE_CLOCK_GETTIME_NSEC_NP_EXITCODE 0)
@@ -75,7 +74,6 @@ if(DARWIN AND NOT DEFINED ANDROID_BUILD)
   endif()
 else()
   set_cache_value(HAVE_CLOCK_MONOTONIC_COARSE_EXITCODE 0)
-  set_cache_value(HAVE_CLOCK_MONOTONIC_EXITCODE 0)
   set_cache_value(HAVE_CLOCK_REALTIME_EXITCODE 0)
   set_cache_value(HAVE_CLOCK_THREAD_CPUTIME_EXITCODE 0)
   set_cache_value(HAVE_MMAP_DEV_ZERO_EXITCODE 0)
@@ -96,7 +94,6 @@ else()
 
   if (FREEBSD)
     set_cache_value(HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP 1)
-    set_cache_value(HAVE_CLOCK_MONOTONIC 1)
     set_cache_value(HAVE_CLOCK_REALTIME 1)
     set_cache_value(HAVE_BROKEN_FIFO_KEVENT_EXITCODE 1)
     set_cache_value(HAVE_PROCFS_STAT 0)

diff --git a/eng/native/tryrun_ios_tvos.cmake b/eng/native/tryrun_ios_tvos.cmake
@@ -5,7 +5,6 @@ endmacro()
 
 set_cache_value(HAVE_SCHED_GETCPU_EXITCODE 1)
 set_cache_value(HAVE_CLOCK_MONOTONIC_COARSE_EXITCODE 1)
-set_cache_value(HAVE_CLOCK_MONOTONIC_EXITCODE 0)
 
 
 # TODO: these are taken from macOS, check these whether they're correct for iOS

diff --git a/src/coreclr/pal/src/config.h.in b/src/coreclr/pal/src/config.h.in
@@ -87,7 +87,6 @@
 #cmakedefine01 HAVE_WORKING_GETTIMEOFDAY
 #cmakedefine01 HAVE_WORKING_CLOCK_GETTIME
 #cmakedefine01 HAVE_CLOCK_THREAD_CPUTIME
-#cmakedefine01 HAVE_CLOCK_MONOTONIC
 #cmakedefine01 HAVE_PTHREAD_CONDATTR_SETCLOCK
 #cmakedefine01 MMAP_ANON_IGNORES_PROTECTION
 #cmakedefine01 ONE_SHARED_MAPPING_PER_FILEREGION_PER_PROCESS

diff --git a/src/coreclr/pal/src/configure.cmake b/src/coreclr/pal/src/configure.cmake
@@ -366,21 +366,7 @@ int main()
 }" HAVE_WORKING_CLOCK_GETTIME)
 set(CMAKE_REQUIRED_LIBRARIES)
 
-set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_RT_LIBS})
-check_cxx_source_runs("
-#include <stdlib.h>
-#include <time.h>
-#include <sys/time.h>
-
-int main()
-{
-  int ret;
-  struct timespec ts;
-  ret = clock_gettime(CLOCK_MONOTONIC, &ts);
 
-  exit(ret);
-}" HAVE_CLOCK_MONOTONIC)
-set(CMAKE_REQUIRED_LIBRARIES)
 
 check_library_exists(${PTHREAD_LIBRARY} pthread_condattr_setclock "" HAVE_PTHREAD_CONDATTR_SETCLOCK)
 

diff --git a/src/coreclr/pal/src/synchmgr/synchmanager.cpp b/src/coreclr/pal/src/synchmgr/synchmanager.cpp
@@ -386,7 +386,7 @@ namespace CorUnix
         if (dwTimeout != INFINITE)
         {
             // Calculate absolute timeout
-            palErr = GetAbsoluteTimeout(dwTimeout, &tsAbsTmo, /*fPreferMonotonicClock*/ TRUE);
+            palErr = GetAbsoluteTimeout(dwTimeout, &tsAbsTmo);
             if (NO_ERROR != palErr)
             {
                 ERROR("Failed to convert timeout to absolute timeout\n");
@@ -1051,7 +1051,7 @@ namespace CorUnix
         ptnwdWorkerThreadNativeData =
             &pSynchManager->m_pthrWorker->synchronizationInfo.m_tnwdNativeData;
 
-        palErr = GetAbsoluteTimeout(WorkerThreadTerminationTimeout, &tsAbsTmo, /*fPreferMonotonicClock*/ TRUE);
+        palErr = GetAbsoluteTimeout(WorkerThreadTerminationTimeout, &tsAbsTmo);
         if (NO_ERROR != palErr)
         {
             ERROR("Failed to convert timeout to absolute timeout\n");
@@ -2671,7 +2671,7 @@ namespace CorUnix
         VolatileStore<DWORD>(pdwWaitState, TWS_ACTIVE);
         m_tsThreadState = TS_STARTING;
 
-#if HAVE_CLOCK_MONOTONIC && HAVE_PTHREAD_CONDATTR_SETCLOCK
+#if HAVE_PTHREAD_CONDATTR_SETCLOCK
         attrsPtr = &attrs;
         iRet = pthread_condattr_init(&attrs);
         if (0 != iRet)
@@ -2699,7 +2699,7 @@ namespace CorUnix
             pthread_condattr_destroy(&attrs);
             goto IPrC_exit;
         }
-#endif // HAVE_CLOCK_MONOTONIC && HAVE_PTHREAD_CONDATTR_SETCLOCK
+#endif // HAVE_PTHREAD_CONDATTR_SETCLOCK
 
         iEagains = 0;
     Mutex_retry:
@@ -2990,41 +2990,32 @@ namespace CorUnix
 
     Converts a relative timeout to an absolute one.
     --*/
-    PAL_ERROR CPalSynchronizationManager::GetAbsoluteTimeout(DWORD dwTimeout, struct timespec * ptsAbsTmo, BOOL fPreferMonotonicClock)
+    PAL_ERROR CPalSynchronizationManager::GetAbsoluteTimeout(DWORD dwTimeout, struct timespec * ptsAbsTmo)
     {
         PAL_ERROR palErr = NO_ERROR;
         int iRet;
 
-#if HAVE_CLOCK_MONOTONIC && HAVE_PTHREAD_CONDATTR_SETCLOCK
-        if (fPreferMonotonicClock)
+#if HAVE_PTHREAD_CONDATTR_SETCLOCK
+        iRet = clock_gettime(CLOCK_MONOTONIC, ptsAbsTmo);
+#elif HAVE_WORKING_CLOCK_GETTIME
+        // Not every platform implements a (working) clock_gettime
+        iRet = clock_gettime(CLOCK_REALTIME, ptsAbsTmo);
+#elif HAVE_WORKING_GETTIMEOFDAY
+        // Not every platform implements a (working) gettimeofday
+        struct timeval tv;
+        iRet = gettimeofday(&tv, NULL);
+        if (0 == iRet)
         {
-            iRet = clock_gettime(CLOCK_MONOTONIC, ptsAbsTmo);
+            ptsAbsTmo->tv_sec  = tv.tv_sec;
+            ptsAbsTmo->tv_nsec = tv.tv_usec * tccMicroSecondsToNanoSeconds;
         }
-        else
-        {
-#endif
-#if HAVE_WORKING_CLOCK_GETTIME
-            // Not every platform implements a (working) clock_gettime
-            iRet = clock_gettime(CLOCK_REALTIME, ptsAbsTmo);
-#elif HAVE_WORKING_GETTIMEOFDAY
-            // Not every platform implements a (working) gettimeofday
-            struct timeval tv;
-            iRet = gettimeofday(&tv, NULL);
-            if (0 == iRet)
-            {
-                ptsAbsTmo->tv_sec  = tv.tv_sec;
-                ptsAbsTmo->tv_nsec = tv.tv_usec * tccMicroSecondsToNanoSeconds;
-            }
 #else
 #ifdef DBI_COMPONENT_MONO
     return ERROR_INTERNAL_ERROR;
 #else
     #error "Don't know how to get hi-res current time on this platform"
 #endif
 #endif // HAVE_WORKING_CLOCK_GETTIME, HAVE_WORKING_GETTIMEOFDAY
-#if HAVE_CLOCK_MONOTONIC && HAVE_PTHREAD_CONDATTR_SETCLOCK
-        }
-#endif
         if (0 == iRet)
         {
             ptsAbsTmo->tv_sec  += dwTimeout / tccSecondsToMilliSeconds;

diff --git a/src/coreclr/pal/src/synchmgr/synchmanager.hpp b/src/coreclr/pal/src/synchmgr/synchmanager.hpp
@@ -775,8 +775,7 @@ namespace CorUnix
 
         static PAL_ERROR GetAbsoluteTimeout(
             DWORD dwTimeout,
-            struct timespec * ptsAbsTmo,
-            BOOL fPreferMonotonicClock);
+            struct timespec * ptsAbsTmo);
     };
 }
 

@@ -260,8 +260,6 @@
 /* Define to 1 if you have the `sigaction' function. */
 #cmakedefine HAVE_SIGACTION 1
 
-/* CLOCK_MONOTONIC */
-#cmakedefine HAVE_CLOCK_MONOTONIC 1
 
 /* clockid_t */
 #cmakedefine HAVE_CLOCKID_T 1

@@ -112,7 +112,6 @@ check_function_exists(clock_gettime HAVE_CLOCK_GETTIME)
 
 check_symbol_exists(madvise "sys/mman.h" HAVE_MADVISE)
 check_symbol_exists(pthread_mutexattr_setprotocol "pthread.h" HAVE_DECL_PTHREAD_MUTEXATTR_SETPROTOCOL)
-check_symbol_exists(CLOCK_MONOTONIC "time.h" HAVE_CLOCK_MONOTONIC)
 
 check_symbol_exists(sys_signame "signal.h" HAVE_SYSSIGNAME)
 check_symbol_exists(pthread_jit_write_protect_np "pthread.h" HAVE_PTHREAD_JIT_WRITE_PROTECT_NP)

@@ -386,15 +386,6 @@ static const int64_t SECS_BETWEEN_1601_AND_1970_EPOCHS = 11644473600LL;
 static const int64_t SECS_TO_100NS = 10000000;
 static const int64_t MSECS_TO_MIS = 1000;
 
-/* clock_gettime () is found by configure on Apple builds, but its only present from ios 10, macos 10.12, tvos 10 and watchos 3 */
-#if defined (HAVE_CLOCK_MONOTONIC) && (defined(HOST_IOS) || defined(HOST_OSX) || defined(HOST_WATCHOS) || defined(HOST_TVOS))
-#undef HAVE_CLOCK_MONOTONIC
-#endif
-
-#ifndef HAVE_CLOCK_MONOTONIC
-static const int64_t MISECS_TO_NS = 1000;
-#endif
-
 static
 int64_t
 system_time_to_int64 (
@@ -466,15 +457,9 @@ system_time_to_int64 (
 int64_t
 ep_rt_mono_system_timestamp_get (void)
 {
-#if HAVE_CLOCK_MONOTONIC
 	struct timespec time;
 	if (clock_gettime (CLOCK_REALTIME, &time) == 0)
 		return system_time_to_int64 (time.tv_sec, time.tv_nsec);
-#else
-	struct timeval time;
-	if (gettimeofday (&time, NULL) == 0)
-		return system_time_to_int64 (time.tv_sec, time.tv_usec * MISECS_TO_NS);
-#endif
 	else
 		return system_time_to_int64 (0, 0);
 }

@@ -190,7 +190,7 @@ mono_clock_get_time_ns (mono_clock_id_t clk_id)
 void
 mono_clock_init (mono_clock_id_t *clk_id)
 {
-#ifdef HAVE_CLOCK_MONOTONIC
+#ifdef CLOCK_MONOTONIC
 	*clk_id = CLOCK_MONOTONIC;
 #endif
 }

diff --git a/src/native/libs/Common/pal_config.h.in b/src/native/libs/Common/pal_config.h.in
@@ -97,7 +97,6 @@
 #cmakedefine01 HAVE_LINUX_ERRQUEUE_H
 #cmakedefine01 HAVE_GETDOMAINNAME_SIZET
 #cmakedefine01 HAVE_INOTIFY
-#cmakedefine01 HAVE_CLOCK_MONOTONIC
 #cmakedefine01 HAVE_CLOCK_REALTIME
 #cmakedefine01 HAVE_CLOCK_GETTIME_NSEC_NP
 #cmakedefine01 HAVE_PTHREAD_CONDATTR_SETCLOCK

diff --git a/src/native/libs/System.Native/pal_crossprocessmutex.c b/src/native/libs/System.Native/pal_crossprocessmutex.c
@@ -41,7 +41,7 @@ static int32_t AcquirePThreadMutexWithTimeout(pthread_mutex_t* mutex, int32_t ti
     timeoutTimeSpec.tv_nsec = (timeoutMilliseconds % 1000) * 1000 * 1000;
 
     error = pthread_mutex_reltimedlock_np(mutex, &timeoutTimeSpec);
-#elif HAVE_PTHREAD_MUTEX_CLOCKLOCK && HAVE_CLOCK_MONOTONIC
+#elif HAVE_PTHREAD_MUTEX_CLOCKLOCK
     error = clock_gettime(CLOCK_MONOTONIC, &timeoutTimeSpec);
     assert(error == 0);
 

diff --git a/src/native/libs/System.Native/pal_threading.c b/src/native/libs/System.Native/pal_threading.c
@@ -64,7 +64,7 @@ LowLevelMonitor* SystemNative_LowLevelMonitor_Create(void)
         return NULL;
     }
 
-#if HAVE_PTHREAD_CONDATTR_SETCLOCK && HAVE_CLOCK_MONOTONIC
+#if HAVE_PTHREAD_CONDATTR_SETCLOCK
     pthread_condattr_t conditionAttributes;
     error = pthread_condattr_init(&conditionAttributes);
     if (error != 0)
@@ -176,7 +176,7 @@ int32_t SystemNative_LowLevelMonitor_TimedWait(LowLevelMonitor *monitor, int32_t
 
     error = pthread_cond_timedwait_relative_np(&monitor->Condition, &monitor->Mutex, &timeoutTimeSpec);
 #else
-#if HAVE_PTHREAD_CONDATTR_SETCLOCK && HAVE_CLOCK_MONOTONIC
+#if HAVE_PTHREAD_CONDATTR_SETCLOCK
     error = clock_gettime(CLOCK_MONOTONIC, &timeoutTimeSpec);
     assert(error == 0);
 #else

diff --git a/src/native/libs/configure.cmake b/src/native/libs/configure.cmake
@@ -558,28 +558,24 @@ if(CLR_CMAKE_TARGET_IOS)
     # Manually set results from check_c_source_runs() since it's not possible to actually run it during CMake configure checking
     unset(HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP)
     unset(HAVE_ALIGNED_ALLOC)   # only exists on iOS 13+
-    set(HAVE_CLOCK_MONOTONIC 1)
     set(HAVE_CLOCK_REALTIME 1)
     unset(HAVE_FORK) # exists but blocked by kernel
 elseif(CLR_CMAKE_TARGET_MACCATALYST)
     # Manually set results from check_c_source_runs() since it's not possible to actually run it during CMake configure checking
     unset(HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP)
     unset(HAVE_ALIGNED_ALLOC)   # only exists on iOS 13+
-    set(HAVE_CLOCK_MONOTONIC 1)
     set(HAVE_CLOCK_REALTIME 1)
     unset(HAVE_FORK) # exists but blocked by kernel
 elseif(CLR_CMAKE_TARGET_TVOS)
     # Manually set results from check_c_source_runs() since it's not possible to actually run it during CMake configure checking
     unset(HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP)
     unset(HAVE_ALIGNED_ALLOC)   # only exists on iOS 13+
-    set(HAVE_CLOCK_MONOTONIC 1)
     set(HAVE_CLOCK_REALTIME 1)
     unset(HAVE_FORK) # exists but blocked by kernel
 elseif(CLR_CMAKE_TARGET_ANDROID)
     # Manually set results from check_c_source_runs() since it's not possible to actually run it during CMake configure checking
     unset(HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP)
     unset(HAVE_ALIGNED_ALLOC) # only exists on newer Android
-    set(HAVE_CLOCK_MONOTONIC 1)
     set(HAVE_CLOCK_REALTIME 1)
 elseif(CLR_CMAKE_TARGET_WASI)
     set(HAVE_FORK 0)
@@ -617,21 +613,6 @@ else()
         "
         HAVE_SHM_OPEN_THAT_WORKS_WELL_ENOUGH_WITH_MMAP)
 
-    check_c_source_runs(
-        "
-        #include <stdlib.h>
-        #include <time.h>
-        #include <sys/time.h>
-        int main(void)
-        {
-            int ret;
-            struct timespec ts;
-            ret = clock_gettime(CLOCK_MONOTONIC, &ts);
-            exit(ret);
-            return 0;
-        }
-        "
-        HAVE_CLOCK_MONOTONIC)
 
     check_c_source_runs(
         "

diff --git a/src/native/minipal/configure.cmake b/src/native/minipal/configure.cmake
@@ -13,7 +13,6 @@ check_function_exists(fsync HAVE_FSYNC)
 check_symbol_exists(arc4random_buf "stdlib.h" HAVE_ARC4RANDOM_BUF)
 check_symbol_exists(getrandom "sys/random.h" HAVE_GETRANDOM)
 check_symbol_exists(O_CLOEXEC fcntl.h HAVE_O_CLOEXEC)
-check_symbol_exists(CLOCK_MONOTONIC time.h HAVE_CLOCK_MONOTONIC)
 check_symbol_exists(CLOCK_MONOTONIC_COARSE time.h HAVE_CLOCK_MONOTONIC_COARSE)
 check_symbol_exists(clock_gettime_nsec_np time.h HAVE_CLOCK_GETTIME_NSEC_NP)
 

diff --git a/src/native/minipal/minipalconfig.h.in b/src/native/minipal/minipalconfig.h.in
@@ -8,7 +8,6 @@
 #cmakedefine01 HAVE_RESOURCE_H
 #cmakedefine01 HAVE_O_CLOEXEC
 #cmakedefine01 HAVE_SYSCTLBYNAME
-#cmakedefine01 HAVE_CLOCK_MONOTONIC
 #cmakedefine01 HAVE_CLOCK_MONOTONIC_COARSE
 #cmakedefine01 HAVE_CLOCK_GETTIME_NSEC_NP
 #cmakedefine01 BIGENDIAN

diff --git a/src/native/minipal/time.c b/src/native/minipal/time.c
@@ -97,25 +97,21 @@ int64_t minipal_hires_ticks(void)
 {
 #if HAVE_CLOCK_GETTIME_NSEC_NP
     return (int64_t)clock_gettime_nsec_np(CLOCK_UPTIME_RAW);
-#elif HAVE_CLOCK_MONOTONIC
+#else
     struct timespec ts;
-    int result = clock_gettime(CLOCK_MONOTONIC, &ts);
-    if (result != 0)
-    {
-        assert(!"clock_gettime(CLOCK_MONOTONIC) failed");
-    }
+    int result;
+    result = clock_gettime(CLOCK_MONOTONIC, &ts);
+    assert(result == 0 && "clock_gettime(CLOCK_MONOTONIC) failed");
 
     return ((int64_t)(ts.tv_sec) * (int64_t)(tccSecondsToNanoSeconds)) + (int64_t)(ts.tv_nsec);
-#else
-    #error "minipal_hires_ticks requires clock_gettime_nsec_np or clock_gettime to be supported."
 #endif
 }
 
 int64_t minipal_lowres_ticks(void)
 {
 #if HAVE_CLOCK_GETTIME_NSEC_NP
     return  (int64_t)clock_gettime_nsec_np(CLOCK_UPTIME_RAW) / (int64_t)(tccMilliSecondsToNanoSeconds);
-#elif HAVE_CLOCK_MONOTONIC
+#else
     struct timespec ts;
 
     // emscripten exposes CLOCK_MONOTONIC_COARSE but doesn't implement it
@@ -129,19 +125,15 @@ int64_t minipal_lowres_ticks(void)
     const clockid_t clockType = CLOCK_MONOTONIC;
 #endif
 
-    int result = clock_gettime(clockType, &ts);
-    if (result != 0)
-    {
+    int result;
+    result = clock_gettime(clockType, &ts);
 #if HAVE_CLOCK_MONOTONIC_COARSE && !defined(__EMSCRIPTEN__)
-        assert(!"clock_gettime(CLOCK_MONOTONIC_COARSE) failed");
+    assert(result == 0 && "clock_gettime(CLOCK_MONOTONIC_COARSE) failed");
 #else
-        assert(!"clock_gettime(CLOCK_MONOTONIC) failed");
+    assert(result == 0 && "clock_gettime(CLOCK_MONOTONIC) failed");
 #endif
-    }
 
     return ((int64_t)(ts.tv_sec) * (int64_t)(tccSecondsToMilliSeconds)) + ((int64_t)(ts.tv_nsec) / (int64_t)(tccMilliSecondsToNanoSeconds));
-#else
-    #error "minipal_lowres_ticks requires clock_gettime_nsec_np or clock_gettime to be supported."
 #endif
 }