Re: [rvm-research] Curious about OpenJDK on JikesRVM

Hi,

On 15.08.2013 20:58, Xi Yang wrote:
> I would like to drop all classes who should be included in JDK
> libraries, and as Maxine does, replace some methods and fields.
> However, I am not sure this is a good idea for GNU Classpath.
> Classpath may already assume any VM implementation would replace those
> classes in "libraryInterface/Common"?

AFAIK the Classpath implementations of things like java.lang.Class just
defer to the corresponding stub class (i.e. VMClass in this case) so we
could just write the appropriate classes if we wanted to. I suppose that
there'll be a detailed discussion on this when the OpenJDK support is
ready for mainline so we don't have to worry about it for now.

> Beside the interface, I think there are two points Jikes did not do it
> very well. One is the list of JDK classes in bootimage, another is the
> the list of classes who should be inited in certain order before
> dynamic loading becoming functional. I think this is a good chance to
> fix them all. Instead of trying many times, and add classes in the
> list manually, we can have a script to figure out candidates. We can
> put why we need to init class X, and the dependence between class
> X,Y,Z  for JDK libraries.

That would indeed be very useful. It would certainly reduce the time
needed to port to new versions of the class libraries. That being said,
I have not looked at this problem at all so I don't know how difficult
it is.

The only thing I can say from memory is that you would likely need to
define a comprehensive set of test programs to run on each image to
ensure that all features work. For example, you will need to check that
the -Xbootclasspath options work (see e.g.
http://jira.codehaus.org/browse/RVM-887 for an issue relating to that).


Kind regards,

Erik Brangs

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