diff -r a5ede748a1d9 src/sim/simulate.cc
--- a/src/sim/simulate.cc	Tue Oct 02 14:35:46 2012 -0500
+++ b/src/sim/simulate.cc	Fri Oct 05 18:47:12 2012 -0400
@@ -39,16 +39,20 @@
 #include "sim/simulate.hh"
 #include "sim/stat_control.hh"
 
 /** Simulate for num_cycles additional cycles.  If num_cycles is -1
  * (the default), do not limit simulation; some other event must
  * terminate the loop.  Exported to Python via SWIG.
  * @return The SimLoopExitEvent that caused the loop to exit.
  */
+
+// record the clock cycle for last exit event
+Tick lastExitTick = 0;
+
 SimLoopExitEvent *
 simulate(Tick num_cycles)
 {
     inform("Entering event queue @ %d.  Starting simulation...\n", curTick());
 
     if (num_cycles < MaxTick - curTick())
         num_cycles = curTick() + num_cycles;
     else // counter would roll over or be set to MaxTick anyhow
@@ -65,16 +69,26 @@ simulate(Tick num_cycles)
         assert(curTick() <= mainEventQueue.nextTick() &&
                "event scheduled in the past");
 
         // forward current cycle to the time of the first event on the
         // queue
         curTick(mainEventQueue.nextTick());
         Event *exit_event = mainEventQueue.serviceOne();
         if (exit_event != NULL) {
+            /*
+             * if there are multiple exit events in the same cycle, drain the
+             * fol drain the following exit events since gem5 only allows one 
+             * exit event in a cycle
+             */ 
+            if (lastExitTick == curTick())
+                continue;
+            else
+                lastExitTick = curTick();
+            
             // hit some kind of exit event; return to Python
             // event must be subclass of SimLoopExitEvent...
             SimLoopExitEvent *se_event;
             se_event = dynamic_cast<SimLoopExitEvent *>(exit_event);
 
             if (se_event == NULL)
                 panic("Bogus exit event class!");