diff -r 8fbf05030e24 -r bc675e55b48c src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Sep 19 08:48:10 2012 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Sep 19 15:48:02 2012 -0700
@@ -789,14 +789,6 @@
   _gc_counters = new CollectorCounters("CMS", 1);
   _completed_initialization = true;
   _inter_sweep_timer.start();  // start of time
-#ifdef SPARC
-  // Issue a stern warning, but allow use for experimentation and debugging.
-  if (VM_Version::is_sun4v() && UseMemSetInBOT) {
-    assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
-    warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
-            " on sun4v; please understand that you are using at your own risk!");
-  }
-#endif
 }
 
 const char* ConcurrentMarkSweepGeneration::name() const {