Suppress error warning in HotSpot backports

[Andrew Haley]

When we run a new VM (post permegen removal) and an old JDK, we
sometimes get a very odd result:

[aph@ ~]$ java -version
java version "1.7.0-internal"
[aph ~]$ java -XX:MaxPermSize=64m  Hello
OpenJDK 64-Bit Server VM warning: ignoring option MaxPermSize=64m; support was removed in 8.0
Hello, World!

Should a warning for an obsolete runtime argument be suppressed if it is
not actually obsolete in that JDK version?

It's easy to suppress this warning; patch attached.  Should we do this?

Andrew.


diff -r 8bca72b725af src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp        Wed Mar 05 16:51:41 2014 +0000
+++ b/src/share/vm/runtime/arguments.cpp        Tue Mar 18 13:55:36 2014 +0000
@@ -861,9 +861,11 @@
   bool has_plus_minus = (*arg == '+' || *arg == '-');
   const char* const argname = has_plus_minus ? arg + 1 : arg;
   if (is_newly_obsolete(arg, &since)) {
-    char version[256];
-    since.to_string(version, sizeof(version));
-    warning("ignoring option %s; support was removed in %s", argname, version);
+    if (JDK_Version::current().compare(since) >= 0) {
+      char version[256];
+      since.to_string(version, sizeof(version));
+      warning("ignoring option %s; support was removed in %s", argname, version);
+    }
     return true;
   }