March 2008

As those who’ve had the unfortunate luck of being in our IRC channel over the past few days will know, I’ve been trying to build IcedTea6 on our Debian etch server again. The good news is it looks like I may have succeeded this time, with some help from Christian Thalinger (twisti) and Gary Benson (gbenson).

Basically most of the tools that come with etch will be useless in your task. The versions of Kaffe, GCJ and GNU Classpath+JamVM that come with it don’t support the 1.5 language extensions. To add insult to injury, because the gcj backport used by Fedora is ’4.1′, IcedTea won’t scream at you for a default ./configure; make. Instead, the OpenJDK sanity check will tell you that you don’t have a 1.6 VM to bootstrap with (although you only actually need a 1.5 one…). This is because IcedTea will symlink bootstrap/jdk1.6.0/bin/java to the gij that is part of etch, which reports itself as 1.4. Similarly, the jar file it picks up is a pre-generics version of Classpath that can’t be used even with a VM that claims to be 1.5.

So you need to build your own Classpath Java stack before proceeding with trying out IcedTea6. This machine is used to do my regression testing for Classpath so I already had an install of 0.97.1, but it’s simple enough to get a copy of GNU Classpath and a compatible VM if you don’t. You CAN use what is installed with etch to build this. The simplest way to do that is to install the java-gcj-compat-dev package which should give you a native version of ecj.

Using this, you can download Classpath 0.97 or any prior version up to 0.95 (the first to include the code merged from the generics branch). ./configure; make; make install should work, but you probably want to use --prefix to install it in a local directory rather than /usr/local/classpath. --disable-plugin is something I also usually add to avoid having to had the Mozilla headers.

Once installed, you need to add a 1.5 VM that works with this. CACAO (from the Mercurial repository), JamVM or the new Kaffe release should work. I used CACAO. You can then configure IcedTea6 by pointing it at the new install. Assuming $CLASSPATH is where you installed everything:

./configure --with-java=$CLASSPATH/bin/java --with-libgcj-jar=$CLASSPATH/share/classpath/ --with-jar=$CLASSPATH/bin/gjar --with-rmic=$CLASSPATH/bin/grmic --with-javah=$CLASSPATH/bin/gjavah

Before building, you also need to patch glibc (thanks to twisti for this tip). Don’t worry! It’s not too scary, just a simple change to a shell script, to make it the same as in more recent versions. On x86, the change is in /usr/lib/ The last line should read:

GROUP ( /lib/ /usr/lib/libc_nonshared.a AS_NEEDED (/lib/ ) )

If you’re on x86_64 or ppc64 (or any 64-bit platform i guess), you need to patch /usr/lib64/

GROUP ( /lib/ /usr/lib/libc_nonshared.a AS_NEEDED ( /lib/ )

That done, you should be able to run make and hopefully reach the message that IcedTea is served. YMMV of course, so let me know how you get on. This was quite a bit easier than when I last remember trying, so hats off to the IcedTea folks for all their hard work. Next stop, Solaris… ;)

It’s that time of year again! This time, I’ll hopefully be mentoring some students instead, especially after my OpenJDK Challenge proposal was accepted. :)

If you’re a prospective student for SoC 2008 and would like to work on Free Java, then please come and join us on either:

Want to find out more? Then mail or hop into #classpath on FreeNode IRC (same network as #gsoc this year).