Index: trunk/libffado/src/libieee1394/ieee1394service.cpp
===================================================================
--- trunk/libffado/src/libieee1394/ieee1394service.cpp (revision 2167)
+++ trunk/libffado/src/libieee1394/ieee1394service.cpp (revision 2171)
@@ -2,4 +2,5 @@
  * Copyright (C) 2005-2008 by Daniel Wagner
  * Copyright (C) 2005-2008 by Pieter Palmers
+ * Copyright (C) 2012 by Jonathan Woithe
  *
  * This file is part of FFADO
@@ -351,16 +352,19 @@
         if (raw1394_read_cycle_timer_and_clock != NULL) {
             err = raw1394_read_cycle_timer_and_clock(m_util_handle, &cycle_timer, &local_time, CLOCK_MONOTONIC_RAW);
-            if (!err)
+            if (!err && Util::SystemTimeSource::setSource(CLOCK_MONOTONIC_RAW)==true)
                 m_have_read_ctr_and_clock = true;
         }
 
-        if (m_have_read_ctr_and_clock)
-            debugOutput(DEBUG_LEVEL_VERBOSE, "This system supports the raw1394_read_cycle_timer_and_clock call, using it.\n");
-        else {
+        if (m_have_read_ctr_and_clock) {
+            debugOutput(DEBUG_LEVEL_VERBOSE, "This system supports the raw1394_read_cycle_timer_and_clock call and the\n");
+            debugOutput(DEBUG_LEVEL_VERBOSE, "CLOCK_MONOTONIC_RAW clock source; using them.\n");
+        } else {
             debugOutput(DEBUG_LEVEL_VERBOSE, "This system supports the raw1394_read_cycle_timer call, using it.\n");
-            debugOutput(DEBUG_LEVEL_NORMAL, "The raw1394_read_cycle_timer_and_clock call is not available.\n");
+            debugOutput(DEBUG_LEVEL_NORMAL, "The raw1394_read_cycle_timer_and_clock call and/or the CLOCK_MONOTONIC_RAW\n");
+            debugOutput(DEBUG_LEVEL_NORMAL, "clock source is not available.\n");
             debugOutput(DEBUG_LEVEL_NORMAL, "Fallback to raw1394_read_cycle_timer.\n");
             debugOutput(DEBUG_LEVEL_NORMAL, "FFADO may be susceptible to NTP-induced clock discontinuities.\n");
-            debugOutput(DEBUG_LEVEL_NORMAL, "Upgrade libraw1394 to version 2.1.0 or later if this is an issue.\n");
+            debugOutput(DEBUG_LEVEL_NORMAL, "If this is an issue, upgrade libraw1394 to version 2.1.0 or later and/or\n");
+            debugOutput(DEBUG_LEVEL_NORMAL, "kernel 2.6.28 or later.\n");
         }
     }
@@ -538,5 +542,6 @@
     if (m_have_read_ctr_and_clock) {
         int err;
-        err = raw1394_read_cycle_timer_and_clock(m_util_handle, cycle_timer, local_time, CLOCK_MONOTONIC_RAW);
+        err = raw1394_read_cycle_timer_and_clock(m_util_handle, cycle_timer, local_time, 
+                  Util::SystemTimeSource::getSource());
         if(err) {
             debugWarning("raw1394_read_cycle_timer_and_clock: %s\n", strerror(err));
Index: trunk/libffado/src/libieee1394/IsoHandlerManager.cpp
===================================================================
--- trunk/libffado/src/libieee1394/IsoHandlerManager.cpp (revision 2076)
+++ trunk/libffado/src/libieee1394/IsoHandlerManager.cpp (revision 2171)
@@ -398,5 +398,5 @@
     int result;
 
-    if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+    if (Util::SystemTimeSource::clockGettime(&ts) == -1) {
         debugError("clock_gettime failed\n");
         return eAR_Error;
Index: trunk/libffado/src/libstreaming/StreamProcessorManager.cpp
===================================================================
--- trunk/libffado/src/libstreaming/StreamProcessorManager.cpp (revision 2107)
+++ trunk/libffado/src/libstreaming/StreamProcessorManager.cpp (revision 2171)
@@ -164,5 +164,5 @@
     if (m_activity_wait_timeout_nsec >= 0) {
 
-        if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+        if (Util::SystemTimeSource::clockGettime(&ts) == -1) {
             debugError("clock_gettime failed\n");
             return eAR_Error;
Index: trunk/libffado/src/debugmodule/debugmodule.cpp
===================================================================
--- trunk/libffado/src/debugmodule/debugmodule.cpp (revision 1999)
+++ trunk/libffado/src/debugmodule/debugmodule.cpp (revision 2171)
@@ -27,4 +27,5 @@
 #include <stdarg.h>
 #include "libutil/ByteSwap.h"
+#include "libutil/Time.h"
 
 #include <iostream>
@@ -180,5 +181,5 @@
     // add a timing timestamp
     struct timespec ts;
-    clock_gettime(CLOCK_MONOTONIC, &ts);
+    Util::SystemTimeSource::clockGettime(&ts);
     uint64_t ts_usec=(uint64_t)(ts.tv_sec * 1000000LL + ts.tv_nsec / 1000LL);
 
Index: trunk/libffado/src/libutil/PosixMessageQueue.cpp
===================================================================
--- trunk/libffado/src/libutil/PosixMessageQueue.cpp (revision 1255)
+++ trunk/libffado/src/libutil/PosixMessageQueue.cpp (revision 2171)
@@ -26,4 +26,5 @@
 #include "Functors.h"
 #include "PosixMutex.h"
+#include "Time.h"
 
 #include <errno.h>
@@ -197,5 +198,5 @@
     while(countMessages()) {
         struct timespec timeout;
-        clock_gettime(CLOCK_REALTIME, &timeout);
+        Util::SystemTimeSource::clockGettime(&timeout);
         timeout.tv_sec += m_timeout.tv_sec;
         timeout.tv_nsec += m_timeout.tv_nsec;
@@ -247,5 +248,5 @@
 
     struct timespec timeout;
-    clock_gettime(CLOCK_REALTIME, &timeout);
+    Util::SystemTimeSource::clockGettime(&timeout);
     timeout.tv_sec += m_timeout.tv_sec;
     timeout.tv_nsec += m_timeout.tv_nsec;
@@ -293,5 +294,5 @@
 
     struct timespec timeout;
-    clock_gettime(CLOCK_REALTIME, &timeout);
+    Util::SystemTimeSource::clockGettime(&timeout);
     timeout.tv_sec += m_timeout.tv_sec;
     timeout.tv_nsec += m_timeout.tv_nsec;
Index: trunk/libffado/src/libutil/SystemTimeSource.cpp
===================================================================
--- trunk/libffado/src/libutil/SystemTimeSource.cpp (revision 1763)
+++ trunk/libffado/src/libutil/SystemTimeSource.cpp (revision 2171)
@@ -1,4 +1,5 @@
 /*
  * Copyright (C) 2005-2008 by Pieter Palmers
+ * Copytight (C) 2012 by Jonathan Woithe
  *
  * This file is part of FFADO
@@ -37,4 +38,31 @@
 namespace Util {
 
+static clockid_t clock_id = CLOCK_REALTIME;
+
+bool
+SystemTimeSource::setSource(clockid_t id)
+{
+    struct timespec tp;
+    // Determine at runtime whether the kernel has support for the
+    // requested clock source.
+    if (clock_gettime(id, &tp) == 0) {
+        clock_id = id;
+        return true;
+    }
+    return false;
+}
+
+clockid_t
+SystemTimeSource::getSource(void)
+{
+    return clock_id;
+}
+
+int
+SystemTimeSource::clockGettime(struct timespec *tp)
+{
+    return clock_gettime(clock_id, tp);
+}
+
 void
 SystemTimeSource::SleepUsecRelative(ffado_microsecs_t usecs)
@@ -44,5 +72,5 @@
     ts.tv_sec = usecs / (1000000LL);
     ts.tv_nsec = (usecs % (1000000LL)) * 1000LL;
-    clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL);
+    clock_nanosleep(clock_id, 0, &ts, NULL);
 }
 
@@ -57,5 +85,5 @@
                        "clock_nanosleep until %"PRId64" sec, %"PRId64" nanosec\n",
                        (int64_t)ts.tv_sec, (int64_t)ts.tv_nsec);
-    int err = clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL);
+    int err = clock_nanosleep(clock_id, TIMER_ABSTIME, &ts, NULL);
     if(err) {
         // maybe signal occurred, but we're going to ignore that
@@ -95,5 +123,5 @@
 {
     struct timespec ts;
-    clock_gettime(CLOCK_REALTIME, &ts);
+    clock_gettime(clock_id, &ts);
     return (ffado_microsecs_t)(ts.tv_sec * 1000000LL + ts.tv_nsec / 1000LL);
 }
Index: trunk/libffado/src/libutil/SystemTimeSource.h
===================================================================
--- trunk/libffado/src/libutil/SystemTimeSource.h (revision 1568)
+++ trunk/libffado/src/libutil/SystemTimeSource.h (revision 2171)
@@ -1,4 +1,5 @@
 /*
  * Copyright (C) 2005-2008 by Pieter Palmers
+ * Copyright (C) 2012 by Jonathan Woithe
  *
  * This file is part of FFADO
@@ -31,4 +32,10 @@
 typedef uint64_t ffado_microsecs_t;
 
+// Ensure this is defined even for kernels/glib versions which don't include
+// it.  This allows compile-time testing for the feature.
+#ifndef CLOCK_MONOTONIC_RAW
+#define CLOCK_MONOTONIC_RAW 4
+#endif
+
 namespace Util {
 
@@ -40,4 +47,8 @@
 
 public:
+    static bool setSource(clockid_t id);
+    static clockid_t getSource(void);
+    static int clockGettime(struct timespec *tp);
+
     static ffado_microsecs_t getCurrentTime();
     static ffado_microsecs_t getCurrentTimeAsUsecs();
Index: trunk/libffado/src/bebob/bebob_dl_mgr.cpp
===================================================================
--- trunk/libffado/src/bebob/bebob_dl_mgr.cpp (revision 2019)
+++ trunk/libffado/src/bebob/bebob_dl_mgr.cpp (revision 2171)
@@ -575,5 +575,5 @@
     struct timespec timeout;
     int retcode;
-    clock_gettime(CLOCK_REALTIME, &timeout);
+    Util::SystemTimeSource::clockGettime(&timeout);
     do {
         printf(".");