Re: Problems with Java with MXE cross-builds

[Michael Goffioul]

On Wed, Nov 27, 2013 at 2:26 PM, Rik <address@hidden> wrote:

On 11/19/2013 09:46 AM, address@hidden wrote:
> Message: 4
> Date: Tue, 19 Nov 2013 09:41:12 -0800 (PST)
> From: PhilipNienhuis <address@hidden>
> To: address@hidden
> Subject: Re: Anyone using Java with recent MinGW builds?
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=us-ascii
>
> Rik-4 wrote
>> > 11/18/13
>> >
>> > I downloaded a copy of Java for Windows XP and every time I try anything
>> > in
>> > Octave (built with MXE) I get a panic and segfault.  Is this something
>> > about the new Java (1.7) from Oracle, or is it with Octave?
> What copy of Java did you download & install? A JDK, a JRE?
>
> Here I've built and used Java support with (cross-built) MinGW binaries ever
> since I figured out how to get Java support cross-compiled in mxe-octave. I
> described that in the maintainers ML (IIRC somewhere in July).
>
> Don't know if it helps but my octave.mk has been attached.
> You'd need to adapt the SHA1 checksum and configure settings. Note that I
> simply copied the contents of Windows <JAVA_HOME>/include/win32/ to Linux
> <JAVA_HOME>/include (a kludge, but I think a decent one at that, for the
> being being). (symlinking from Linux JAVA_HOME to the Windows side didn't
> work with mxe-octave, I didn't bother to investigate)
>
> Philip
> octave.mk <http://octave.1599824.n4.nabble.com/file/n4659319/octave.mk>

11/27/13

This problem is still very much present for me.  I have done nothing
special either on the Linux side or the Windows side.  On the Linux side, I
have Java installed and when I run the MXE cross-build it succeeds.  On the
Windows side I have Windows XP and I just downloaded the standard package
from Oracle which gives me Java 7 Update 45 (probably just a JRE).  I get a
segfault every time when using any Java command.

It seems to me that we may need to be more careful in configure.ac about
distinguishing between $build_os and $host_os.  We require a Java
environment on the $build_os in order to produce .class and .jar files that
are a part of Octave.  We require a jvm on the $host_os in order to run
things, but we can't test that in a cross-compiling situation and should
just assume "yes".

For any Java experts, is it possible that the problem is architecture
related (32-bit vs. 64-bit).  My build platform is x86_64  Linux, but
Windows XP Home Edition is 32 bit.

See this link [1]. For plain Java, it shouldn't be a problem. Java is "compile-once-run-everywhere". However, there might be problems if the java integration part of octave was compiled with 64 bits header files.

Michael.

[1] http://stackoverflow.com/questions/783662/java-32-bit-vs-64-bit-compatibility