Re: Developing VM

[Peter Werno]

Hello Mark,

> Hi,
>
> On Sun, 2003-08-10 at 15:32, Peter Werno wrote:
>> we are developing a new Virtual Machine for Amiga OS
>> (http://sourceforge.net/projects/jamiga) which will be bundled with
>> the GNU classpath.
>
> Nice. Hope you find GNU Classpath useful for bringing a VM to that
> platform.
>

Yes, indeed. We tried with Sun's rt.jar first, but their documentation
...uhm... well ...
plus they were never answering any of our requests (e.g. wether or not we
could include the rt.jar with our vm). Once we moved to GNU classpath, it
took us only 2-3 days to "replace" everything and it now runs much
smoother :-)

>> Our VM is following a differnet approach and JNI has not been
>> implemented yet. Moreover, we tend to implement a lot of the core
>> functions/classes natively straight into the VM, as the older
>> 68K-processors of the Amiga-Systems are not really up to speed with
>> modern Intel or IBM-chips!
>
> In principle GNU Classpath can be used by VMs that don't support JNI.
> But JNI makes things a lot easier since for almost everything we supply
> native JNI C based implementations. But we also try to setup everything
> so that classes don't need explicit native methods. In principle every
> class that needs native or VM support (or a particular system/VM
> optimization) delegates to a package private final VMSomething class
> that is VM dependent and that does the correct thing on that VM (so if
> the VM supports JNI then in most cases it can use the default
> vm/reference classes that use the supplied native JNI implementations.
>
> But this support is not complete yet so we need developers of VMs that
> don't support JNI to help us point out where we need to abstract away
> from direct native methods. Welcome! You have just volunteered :)
>

I will help wherever I can :-)
>From the top of my head ... there is this "TimeZone" - class in the
java.util - package which defines a "getDefaultTimeZoneId" - method. Would
it make sense to redirect this to - say - the java.lang.VMSystem - class?
(The currentTimeMillis is defined in "System" too, so it's not too far off
:-) )

>> For this reason, it would be very useful, if we could get information
>> on changes, especially where native method calls are involved.
>>
>> Would this kind of information usually be broadcasted on this mailing
>> list, or are there different channels that I should subscribe to?
>
> There are two mailinglist: http://savannah.gnu.org/mail/?group=classpath
> address@hidden and address@hidden The first one (this
> mailinglist) is were all the technical discussion takes place, also
> discussion related to VM interface changes (which should always be
> listed in the NEWS file).
> If you want to follow development closely then you also need to
> subscribe to the second mailinglist which gets email whenever code in
> CVS changes or the bug or patch tracker record changes.
>
> Cheers,
>
> Mark

I will check that out! Thank you very much,

Peter Werno