--- a/src/share/vm/runtime/arguments.cpp	Wed Aug 22 17:05:22 2012 -0700
+++ b/src/share/vm/runtime/arguments.cpp	Fri Aug 24 13:17:44 2012 -0700
@@ -829,6 +829,9 @@
     } else {
       jio_fprintf(defaultStream::error_stream(), "%s", locked_message_buf);
     }
+  } else {
+    jio_fprintf(defaultStream::error_stream(),
+                "Unrecognized VM option '%s'\n", argname);
   }
 
   // allow for commandline "commenting out" options like -XX:#+Verbose

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/runtime/7162488/Test7162488.sh	Fri Aug 24 13:17:44 2012 -0700
@@ -0,0 +1,77 @@
+#
+#  Copyright (c) 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
+#  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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+#  or visit www.oracle.com if you need additional information or have any
+#  questions.
+#
+
+
+# @test Test7162488.sh
+# @bug 7162488
+# @summary VM not printing unknown -XX options
+# @run shell Test7162488.sh
+#
+
+if [ "${TESTSRC}" = "" ]
+  then TESTSRC=.
+fi
+
+if [ "${TESTJAVA}" = "" ]
+then
+  PARENT=`dirname \`which java\``
+  TESTJAVA=`dirname ${PARENT}`
+  printf "TESTJAVA not set, selecting " ${TESTJAVA}
+  printf "  If this is incorrect, try setting the variable manually.\n"
+fi
+
+# set platform-dependent variables
+OS=`uname -s`
+case "$OS" in
+  Windows_* )
+    FS="\\"
+    ;;
+  * )
+    FS="/"
+    ;;
+esac
+
+JAVA=${TESTJAVA}${FS}bin${FS}java
+
+#
+# Just run with an option we are confident will not be recognized,
+# and check for the message:
+#
+OPTION=this_is_not_an_option
+
+${JAVA} ${TESTVMOPTS} -showversion -XX:${OPTION} 2>&1 | grep "Unrecognized VM option" 
+if [ "$?" != "0" ]
+then
+  printf "FAILED: option not flagged as unrecognized.\n"
+  exit 1
+fi
+
+${JAVA} ${TESTVMOPTS} -showversion -XX:${OPTION} 2>&1 | grep ${OPTION}
+if [ "$?" != "0" ]
+then
+  printf "FAILED: bad option not named as being bad.\n"
+  exit 1
+fi
+
+printf "Passed.\n"
+