64-bit client VM

David Holmes David.Holmes at oracle.com
Sat Jun 25 03:05:24 PDT 2011

Aekold Helbrass said the following on 06/25/11 19:37:
> Sorry if this is wrong mailing list to ask that question, but it's the
> only one that looks suitable by its description...

It's really a hotspot question so I've cc'ed that list.

> README file tells "64-bit client builds are not directly supported". So:
> 1) What is the reason of this? Does it mean that client vm source code
> was not adapted to 64-bit systems or just that Sun/Oracle don't want
> to provide technical support for this?

We don't build it nor test it on a regular basis internally. The code 
was originally developed for a proprietary product - Sun Java Real-Time 
System - and was then added to OpenJDK. We don't officially support it.

> 2) How badly unsupported it it? Will it work fine but possibly will
> have some bugs, will it work fine but not as efficient as 32-bit
> client, or it will hardly work at all?

I don't know where it stands regarding support for latest Java 7 
features, but otherwise it should work ok. No idea how to compare 
performance against 32-bit client.

Build it and see is all I can advise. The Makefiles will need some 
tweaking to allow this when doing a full JDK build. Otherwise I think 
you can just do:

cd hotspot/make
make LP64=1 product1

David Holmes

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