OpenJDK & Cacao & GCJ & Java defaults in unstable

[Matthias Klose <doko@debian.org>]

Hi,

openjdk-6 in unstable is updated to the 6b14 code drop, built from a recent
IcedTea snapshot. There are a few regressions in the ports which don't use the
hotspot VM, but the Zero VM. Help from porters would be appreciated.

There are two new binary packages offering additional JVMs:

 - openjdk-6-jre-zero: built on amd64 and i386. This is the JVM used by
   default on the non-hotspot archs (armel, alpha, s390, mips, mipsel,
   powerpc, m68k?). Maybe useful for debugging issues with the zero JVM on
   archs which are more accessible.

 - icedtea-6-jre-cacao: built on alpha, armel, mips, mipsel, s390, i386,
   amd64, powerpc). The Cacao JVM and JIT is not yet feature complete
   compared to the hotspot JVM, but is much faster than the Zero JVM
   and offers an alternative on platforms which don't have the Hotspot
   JVM.

The additional JVM's can be called with

  java [-cacao|-zero]

or for the java tools with

  <tool name> [-J-cacao|-J-zero]

This is currently a Debian/Ubuntu only option; integration into IcedTea is in
progress.

To make a JVM the default, make it the first one in /etc/java-6-openjdk/jvm.cfg.

GCJ is still the work horse to build and bootstrap OpenJDK. IMO it still does
make sense to keep the '-gcj' packages for software which is known to work with
GCJ. I plan to have a recent GCJ-4.x release for the next Debian release.

Once openjdk-6 moves to testing, I propose to change the default in the
default-{jre,jdk} packages to point to the openjdk-6 packages. This works well,
except for one thing: packages will be built with -source 1.6 by default, which
makes the resulting .class/.jar files unusable with older java versions (1.4 and
1.5). I would like to propose a change in the Debian java policy, that java
packages must be built for the version which is sufficient for a sucessful
build. The changes are trivial; I already did check in changes for ant and ant
build- and runtime dependencies into the debian-java svn.

There is currently work-in-progress to extend the Zero JVM with a JIT (called
shark).  This is still experimental work, currently requires llvm-2.4 (unstable
has 2.5). I would welcome feedback from port maintainers about zero/shark.
Please consider to join the IcedTea mailing list.

  Matthias

PS: I would appreciate some help with openjdk in Debian; the current maintainer
team is MIA or inactive.