diff -r b5187256db43 -r 64a4d03bc18f src/dev/alpha/tsunami_io.hh
--- a/src/dev/alpha/tsunami_io.hh	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/alpha/tsunami_io.hh	Wed Aug 11 14:35:52 2010 -0700
@@ -141,6 +141,12 @@
     void clearPIC(uint8_t bitvector);
 
     /**
+     * Drain the io state including all associated events.
+     * @param drainEvent
+     */
+    unsigned int drain(Event *de);
+
+    /**
      * Serialize this object to the given output stream.
      * @param os The stream to serialize to.
      */
diff -r b5187256db43 -r 64a4d03bc18f src/dev/alpha/tsunami_io.cc
--- a/src/dev/alpha/tsunami_io.cc	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/alpha/tsunami_io.cc	Wed Aug 11 14:35:52 2010 -0700
@@ -249,6 +249,17 @@
     }
 }
 
+unsigned int 
+TsunamiIO::drain(Event *de)
+{
+    unsigned int count = 0;
+    count += pitimer.drain(de);
+    count += rtc.drain(de);
+    assert(count == 0);
+    changeState(SimObject::Drained);
+    return count;
+}
+
 void
 TsunamiIO::serialize(ostream &os)
 {
diff -r b5187256db43 -r 64a4d03bc18f src/dev/intel_8254_timer.hh
--- a/src/dev/intel_8254_timer.hh	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/intel_8254_timer.hh	Wed Aug 11 14:35:52 2010 -0700
@@ -137,6 +137,10 @@
         /** Pointer to container */
         Intel8254Timer *parent;
 
+        /** if non-zero, the scheduled tick of an event used for drain
+            serialization coordination */
+        Tick event_tick;
+
       public:
         Counter(Intel8254Timer *p, const std::string &name, unsigned int num);
 
@@ -165,6 +169,12 @@
         bool outputHigh();
 
         /**
+         * Drain all associated events.
+         * @param drainEvent
+         */
+        unsigned int drain(Event *de);
+
+        /**
          * Serialize this object to the given output stream.
          * @param base The base name of the counter object.
          * @param os   The stream to serialize to.
@@ -229,6 +239,8 @@
         return counter[num]->outputHigh();
     }
 
+    unsigned int drain(Event *de);
+
     /**
      * Serialize this object to the given output stream.
      * @param base The base name of the counter object.
diff -r b5187256db43 -r 64a4d03bc18f src/dev/intel_8254_timer.cc
--- a/src/dev/intel_8254_timer.cc	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/intel_8254_timer.cc	Wed Aug 11 14:35:52 2010 -0700
@@ -32,6 +32,7 @@
 
 #include "base/misc.hh"
 #include "dev/intel_8254_timer.hh"
+#include "sim/sim_object.hh"
 
 using namespace std;
 
@@ -69,6 +70,17 @@
     }
 }
 
+unsigned int 
+Intel8254Timer::drain(Event *de)
+{
+    unsigned int count = 0;
+    count += counter[0]->drain(de);
+    count += counter[1]->drain(de);
+    count += counter[2]->drain(de);
+    assert(count == 0);
+    return count;
+}
+
 void
 Intel8254Timer::serialize(const string &base, ostream &os)
 {
@@ -216,6 +228,18 @@
     return output_high;
 }
 
+unsigned int 
+Intel8254Timer::Counter::drain(Event *de)
+{
+    if (event.scheduled()) {
+        event_tick = event.when();
+        parent->deschedule(event);
+    } else {
+        event_tick = 0;
+    }
+    return 0;
+}
+
 void
 Intel8254Timer::Counter::serialize(const string &base, ostream &os)
 {
@@ -227,10 +251,6 @@
     paramOut(os, base + ".latch_on", latch_on);
     paramOut(os, base + ".read_byte", read_byte);
     paramOut(os, base + ".write_byte", write_byte);
-
-    Tick event_tick = 0;
-    if (event.scheduled())
-        event_tick = event.when();
     paramOut(os, base + ".event_tick", event_tick);
 }
 
@@ -247,7 +267,6 @@
     paramIn(cp, section, base + ".read_byte", read_byte);
     paramIn(cp, section, base + ".write_byte", write_byte);
 
-    Tick event_tick;
     paramIn(cp, section, base + ".event_tick", event_tick);
     if (event_tick)
         parent->schedule(event, event_tick);
diff -r b5187256db43 -r 64a4d03bc18f src/dev/mc146818.hh
--- a/src/dev/mc146818.hh	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/mc146818.hh	Wed Aug 11 14:35:52 2010 -0700
@@ -119,6 +119,10 @@
     /** RTC status register B */
     uint8_t stat_regB;
 
+    /** RTC event times for drain and serialization coordination */
+    Tick rtcTimerInterruptTickOffset;
+    Tick rtcClockTickOffset;
+
   public:
     MC146818(EventManager *em, const std::string &name, const struct tm time,
             bool bcd, Tick frequency);
@@ -132,6 +136,8 @@
 
     void tickClock();
 
+    unsigned int drain(Event *de);
+
     /**
       * Serialize this object to the given output stream.
       * @param base The base name of the counter object.
diff -r b5187256db43 -r 64a4d03bc18f src/dev/mc146818.cc
--- a/src/dev/mc146818.cc	Wed Aug 11 14:35:52 2010 -0700
+++ b/src/dev/mc146818.cc	Wed Aug 11 14:35:52 2010 -0700
@@ -40,6 +40,7 @@
 #include "base/trace.hh"
 #include "dev/mc146818.hh"
 #include "dev/rtcreg.h"
+#include "sim/sim_object.hh"
 
 using namespace std;
 
@@ -105,8 +106,12 @@
 
 MC146818::~MC146818()
 {
-    deschedule(tickEvent);
-    deschedule(event);
+    if (tickEvent.scheduled()) {
+        deschedule(tickEvent);
+    }
+    if (event.scheduled()) {
+        deschedule(event);
+    }
 }
 
 void
@@ -203,6 +208,20 @@
     setTime(*gmtime(&calTime));
 }
 
+unsigned int 
+MC146818::drain(Event *de)
+{
+    if (event.scheduled()) {
+        rtcTimerInterruptTickOffset = event.when() - curTick;
+        rtcClockTickOffset = event.when() - curTick;
+        deschedule(event);
+    }
+    if (tickEvent.scheduled()) {
+        deschedule(tickEvent);
+    }
+    return 0;
+}
+
 void
 MC146818::serialize(const string &base, ostream &os)
 {
@@ -214,9 +233,7 @@
     // save the timer tick and rtc clock tick values to correctly reschedule 
     // them during unserialize
     //
-    Tick rtcTimerInterruptTickOffset = event.when() - curTick;
     SERIALIZE_SCALAR(rtcTimerInterruptTickOffset);
-    Tick rtcClockTickOffset = event.when() - curTick;
     SERIALIZE_SCALAR(rtcClockTickOffset);
 }