Re: Problems with Java with MXE cross-builds

[PhilipNienhuis]

Michael Goffioul wrote
> On Wed, Nov 27, 2013 at 2:26 PM, Rik <

> rik@

> > wrote:
> 
>> On 11/19/2013 09:46 AM, 

> octave-maintainers-request@

>  wrote:
>> > Message: 4
>> > Date: Tue, 19 Nov 2013 09:41:12 -0800 (PST)
>> > From: PhilipNienhuis <

> pr.nienhuis@

> >
>> > To: 

> octave-maintainers@

>> > 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
>> &lt;http://octave.1599824.n4.nabble.com/file/n4659319/octave.mk&gt;
>>
>> 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

FWIW, at work on my W64-bit Win7 box, Java in an mxe cross-built Octave (on
32 bit Linux) didn't work with a 64-bit JDK. I had to install a 32 bit JDK
to get Java support in Octave to work. 

So the "compile-once-run-everywhere" doesn't seem to work in all cases.

Philip



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