diff -r 23b52cd6ca73 -r 36458db4ccf5 hotspot/src/share/vm/memory/cardTableModRefBS.hpp
--- a/hotspot/src/share/vm/memory/cardTableModRefBS.hpp	Tue Mar 13 21:12:53 2012 +0100
+++ b/hotspot/src/share/vm/memory/cardTableModRefBS.hpp	Wed Mar 14 12:49:27 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -72,6 +72,9 @@
     CT_MR_BS_last_reserved      = 16
   };
 
+  // a word's worth (row) of clean card values
+  static const intptr_t clean_card_row = (intptr_t)(-1);
+
   // dirty and precleaned are equivalent wrt younger_refs_iter.
   static bool card_is_dirty_wrt_gen_iter(jbyte cv) {
     return cv == dirty_card || cv == precleaned_card;