diff -r 0f62a53fae43 src/share/vm/prims/jvm.cpp
--- a/src/share/vm/prims/jvm.cpp	Mon Jun 04 09:17:47 2012 -0400
+++ b/src/share/vm/prims/jvm.cpp	Tue Jun 05 22:29:28 2012 -0400
@@ -345,9 +345,13 @@
   // Do this after setting user properties to prevent people
   // from setting the value with a -D option, as requested.
   {
-    char as_chars[256];
-    jio_snprintf(as_chars, sizeof(as_chars), INTX_FORMAT, MaxDirectMemorySize);
-    PUTPROP(props, "sun.nio.MaxDirectMemorySize", as_chars);
+    if (FLAG_IS_DEFAULT(MaxDirectMemorySize)) {
+      PUTPROP(props, "sun.nio.MaxDirectMemorySize", "-1");
+    } else {
+      char as_chars[256];
+      jio_snprintf(as_chars, sizeof(as_chars), UINTX_FORMAT, MaxDirectMemorySize);
+      PUTPROP(props, "sun.nio.MaxDirectMemorySize", as_chars);
+    }
   }
 
   // JVM monitoring and management support
diff -r 0f62a53fae43 src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp	Mon Jun 04 09:17:47 2012 -0400
+++ b/src/share/vm/runtime/arguments.cpp	Tue Jun 05 22:29:28 2012 -0400
@@ -2708,6 +2708,17 @@
         return JNI_EINVAL;
       }
       FLAG_SET_CMDLINE(uintx, ConcGCThreads, conc_threads);
+    } else if (match_option(option, "-XX:MaxDirectMemorySize=", &tail)) {
+      julong max_direct_memory_size = 0;
+      ArgsRange errcode = parse_memory_size(tail, &max_direct_memory_size, 0);
+      if (errcode != arg_in_range) {
+	jio_fprintf(defaultStream::error_stream(),
+		    "Invalid maximum direct memory size: %s\n",
+		    option->optionString);
+	describe_range_error(errcode);
+	return JNI_EINVAL;
+      }
+      FLAG_SET_CMDLINE(uintx, MaxDirectMemorySize, max_direct_memory_size);
     } else if (match_option(option, "-XX:", &tail)) { // -XX:xxxx
       // Skip -XX:Flags= since that case has already been handled
       if (strncmp(tail, "Flags=", strlen("Flags=")) != 0) {
diff -r 0f62a53fae43 src/share/vm/runtime/globals.hpp
--- a/src/share/vm/runtime/globals.hpp	Mon Jun 04 09:17:47 2012 -0400
+++ b/src/share/vm/runtime/globals.hpp	Tue Jun 05 22:29:28 2012 -0400
@@ -3703,7 +3703,7 @@
                                                                             \
   /* Properties for Java libraries  */                                      \
                                                                             \
-  product(intx, MaxDirectMemorySize, -1,                                    \
+  product(uintx, MaxDirectMemorySize, 0,                                    \
           "Maximum total size of NIO direct-buffer allocations")            \
                                                                             \
   /* temporary developer defined flags  */                                  \