[fedora-java] Re: ld doesn't know about location of libjvm

[Braden McDaniel]

Thomas Fitzsimmons wrote:
> Hi,
> 
> Braden McDaniel wrote:
>> On Sun, 29 Oct 2006 14:21:29 -0500, Thomas Fitzsimmons wrote:
>>
>>> Hi,
>>>
>>> Braden McDaniel wrote:
>>>> ld seems not to know about /usr/lib[64]/gcj-4.1.1; and as such 
>>>> cannot find libjvm.so without a -L flag. Is this deliberate or a bug?
>>> This is deliberate.  You should be dlopen'ing libjvm.so rather than 
>>> linking to it directly.  To locate it, use 
>>> $JAVA_HOME/jre/lib/i386/client/libjvm.so like you would on other 
>>> JVMs. java-1.4.2-gcj-compat symlinks 
>>> /usr/lib/jvm/java/jre/lib/i386/client/libjvm.so to libgcj's libjvm 
>>> implementation.
>>
>> Fair enough; but I don't want to force my users to set JAVA_HOME. Is this
>> prefix build-time discoverable?
> 
> If you're willing to require GCJ's implementation then you can count on 
> libjvm.so being located at:
> 
> /usr/lib/jvm/java-1.4.2-gcj/jre/lib/$arch/client/libjvm.so

On recent Fedora, perhaps; but I'm inclined not to depend on the 
java-1.4.2-gcj-compat in general since I don't know how widely it's 
coupled to gcj deployments.

What I'd like to support is preference for the libjvm relative to 
JAVA_HOME at run-time; but falling back to a location established for 
libjvm at build-time (if JAVA_HOME is not set at run-time).

> where $arch is the rpm architecture string.  To print this string for 
> the target system, use:
> 
> rpm --eval "%{_arch}"

Not a solution for systems that aren't RPM-based. (But not a problem for 
me; autoconf solves this.)

> If you'd like to require any JPackage JRE then the architecture string 
> may be a little different (e.g., amd64 vs. x86_64) but the location will 
> be:
> 
> /usr/lib/jvm/jre/lib/$arch/client/libjvm.so
> 
> If you'd like to support other types of JDK installations like /opt or 
> /usr/java then you'll have to do a runtime search.

It's looking like my best option is to eke out all the information I can 
from libgcj.pc. Assuming libjvm.so is reliably installed in 
${libdir}/gcj-${gcj_version} across distributions, I should be able to 
get what I need from it.

Braden