--with-jni-libpath not taken into account

[mbaudier]

On Linux (Debian 13/trixie x86_64), the configure option --with-jni-libpath to change the default JNI path does not seem to be taken into account.

For example, this build:

sh configure --with-jni-libpath=/usr/lib/jni:/usr/lib/x86_64-linux-gnu/jni

Then returns the default:

./build/linux-x86_64-server-release/jdk/bin/jshell << EOF
System.getProperty("java.library.path")
EOF
jshell> $1 ==> "<absolute path to working copy>/build/linux-x86_64-server-release/jdk/lib/default:<absolute path to working copy>/build/linux-x86_64-server-release/jdk/lib:/usr/lib64:/usr/lib"

Tests with actual JNI libraries do not work unless -Djava.library.path is explicitly set (here with the SWT Hello World [1]):

# sudo apt install libswt-gtk-4-java
./build/linux-x86_64-server-release/jdk/bin/java -cp /usr/share/java/swt4.jar Snippet1.java 
Exception in thread "main" java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: 
	Can't load swt-gtk-4962r3
	Can't load swt-gtk
	Can't load swt
	Can't load /usr/lib/jni/libswt-gtk.so
	Can't load /usr/lib/jni/libswt.so
	Can't load /home/mbaudier/.swt/lib/linux/x86_64/libswt-gtk-4962r3.so
	Can't load /home/mbaudier/.swt/lib/linux/x86_64/libswt-gtk.so
	Can't load /home/mbaudier/.swt/lib/linux/x86_64/libswt.so

./build/linux-x86_64-server-release/jdk/bin/java -Djava.library.path=/usr/lib/jni:/usr/lib/x86_64-linux-gnu/jni -cp /usr/share/java/swt4.jar Snippet1.java
# show SWT windows

The default Debian OpenJDK (openjdk-21-jdk) does not need -Djava.library.path since it has been built with this configuration option [2].

Does OpenJ9 use another mechanism to override the default JNI path at build time?

[1] https://github.com/eclipse-platform/eclipse.platform.swt/blob/master/examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet1.java
[2] https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-21/debian/rules?ref_type=heads#L412

[keithc-ca]

The configuration option --with-jni-libpath is used in the definition of HOTSPOT_OVERRIDE_LIBPATH. Based on that name, it shouldn't surprise anyone that this is only relevant to HotSpot. I don't think OpenJ9 currently has a mechanism to influence the default JNI path: I created eclipse-openj9/openj9#23011 to consider changing that.