[LLVMdev] [VMKit] OpenJDK Port

Nicolas Geoffray nicolas.geoffray at gmail.com
Wed Sep 21 13:12:30 PDT 2011

Hi Will,

On Wed, Sep 21, 2011 at 12:34 AM, Will Dietz <willdtz at gmail.com> wrote:

> On Tue, Aug 16, 2011 at 1:45 PM, Nicolas Geoffray
> <nicolas.geoffray at gmail.com> wrote:
> >> Supporting OpenJDK is very interesting indeed, as full 1.6 support is
> >> important to us.  How intense of a project would undertaking this be?
> >> And is this something you could semi-mentor on if I were to undertake
> >> it? :).
> >
> > Yes, no problem. I'd be happy to help in any way if you were to implement
> > it. And I'd *really* want this to happen. GNU Classpath is not evolving
> > anymore, and still has some compatibilities/performance problems.
> > I don't know how decoupled from the runtime the OpenJDK libraries are,
> but
> > on the VMKit front, it should not be too hard to replace GNU Classpath's
> > requirements with OpenJDK's. You just need to be really familiar with
> > OpenJDK on how the boot system works.
> >
> Hi Nicolas,
> I'm writing you to let you know that I've begun work on this (porting
> VMKit to OpenJDK), and I've reached the point where I'd like to start
> a conversation with you about the entire process/project, and to start
> working towards getting these changes pushed upstream as appropriate.
> I'm especially keen on getting some feedback/discussion/code review,
> as while I'm making good progress much of this is new to me and it can
> be tricky to get right.
> To give you a rough idea of the status of this work: the present port
> can bootstrap (including the optional precompilation) and can run
> things like "Hello World" and other similarly trivial applications.

That's awesome!

> While I'm sure there are a few core issues, I think at the moment the
> largest deficiency is an incomplete implementation of the
> JVM/JNI/sun.misc.Unsafe.* set of calls.

Is that a big stopper? Without implementing full JNI nor sun.misc.Unsafe,
VMKit can go pretty far with GNU Classpath.

> Anyway, please let me know your thoughts on this and how to best move
> forward (should I start sending patches? where? where should
> discussion go? etc).

I'd be really happy to provide any help/review on your changes. Please send
a patch to vmkit-commits, we can discuss them here. I am looking forward to
it. Ideally, we should be able to define an interface between VMKit and the
different libraries (OpenJDK and GNU Classpath), so we can all work on

I'm really enthusiastic about this!


> Thanks for your time,
> ~Will
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