diff -r 000000000000 -r a61af66fc99e src/share/vm/runtime/atomic.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/runtime/atomic.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2001-2003 Sun Microsystems, Inc.  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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_atomic.cpp.incl"
+
+jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
+  assert(sizeof(jbyte) == 1, "assumption.");
+  uintptr_t dest_addr = (uintptr_t)dest;
+  uintptr_t offset = dest_addr % sizeof(jint);
+  volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
+  jint cur = *dest_int;
+  jbyte* cur_as_bytes = (jbyte*)(&cur);
+  jint new_val = cur;
+  jbyte* new_val_as_bytes = (jbyte*)(&new_val);
+  new_val_as_bytes[offset] = exchange_value;
+  while (cur_as_bytes[offset] == compare_value) {
+    jint res = cmpxchg(new_val, dest_int, cur);
+    if (res == cur) break;
+    cur = res;
+    new_val = cur;
+    new_val_as_bytes[offset] = exchange_value;
+  }
+  return cur_as_bytes[offset];
+}