OpenJDK compilation

[Christian Thalinger]

On Tue, 2008-07-22 at 09:44 -0700, Kelly O'Hair wrote:
> 
> Sorgius, Aaron wrote:
> > Oops... sorry Xerxes, I left you off my replies.  Just trying to get Java on ARM 
> > 
> > 
> >> Aaron Sorgius wrote:
> > 
> >>> I've been trying to google for some how-to's on getting OpenJDK 
> >>> compiled on ARM (cortex-A8 specifically).  I came across your website 
> >>> and it looks like you are doing some things that might be able to 
> >>> point me in a helpful direction.  I was hoping to cross compile using 
> >>> an Ubuntu machine.  I have it compiling natively on Ubuntu, but don't 
> >>> know the best way to build for ARM.  Any suggestions?
> > 
> > OpenJDK doesn't support cross-compilation.  It should.
> 
> In general The JDK team hasn't had a need to do much cross-compilation,
> with the exception of our past use of Windows X86 to build Windows IA64
> (which is a special case of cross-compilation).
> 
> In the hotspot Makefiles there is a REMOTE variable that can be used to
> cause certain rules to be built with a prefix, such as 'ssh someothermachine'.
> This is usually used to run the JDK javac on a different machine, since
> it doesn't matter where the class file is compiled (this REMOTE assumes
> a shared file system of course).
> 
> The JDK builds require a bootstrap JDK, but the JDK build can easily
> be primed on a supported machine, and the native libraries displaced.
> The JDK Makefiles don't have any kind of REMOTE feature, but that's
> certainly possible. (See jdk/make/common/shared/Defs-java.gmk)
> http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/tip/make/common/shared/Defs-java.gmk
> 
> The JDK build itself is not used during the build procedure until it's
> needed to build the demos, just before the JDK images target.
> So I imagine the build can only get as far as just before creating
> images.
> 
> So doing cross compilation is certainly possible, just not easy.
> Every time I talk to someone wanting cross-compilation, it turns out
> that they have a very specific situation of cross-compilation, not
> all situations are the same. I don't see a solution for all situations.

Hi!

I have successfully cross-compiled IcedTea on x86_64 Linux for ARM Linux
(with CACAO as VM).  Except some stuff I have disabled in the build
system, because I didn't have the headers and libraries (ALSA, ...), all
stuff is working, like AWT/Swing.

The only problem during cross-compilation is the sizer.32 executable,
which has to be run on the target machine:

$ file ./gensrc/sun/awt/X11/generator/sizer.32
./gensrc/sun/awt/X11/generator/sizer.32: ELF 32-bit LSB executable, ARM,
version 1 (SYSV), for GNU/Linux 2.6.14, dynamically linked (uses shared
libs), not stripped

But this can be done manually and the result file copied over into the
cross-build system.

- twisti