Currently the runtime/SharedArchiveFile/CheckDefaultArchiveFile.java test fails on AIX .
It runs into this NPE :

java.lang.NullPointerException
at java.base/sun.nio.fs.UnixPath.normalizeAndCheck(UnixPath.java:75)
at java.base/sun.nio.fs.UnixPath.<init>(UnixPath.java:69)
at java.base/sun.nio.fs.UnixFileSystem.getPath(UnixFileSystem.java:279)
at java.base/java.nio.file.Path.of(Path.java:147)
at java.base/java.nio.file.Paths.get(Paths.java:69)
at CheckDefaultArchiveFile.main(CheckDefaultArchiveFile.java:51)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:830)

Reason is that the path to the classes.jsa is null, which is correct on a non CDS platform (like AIX).
However the test does not handle this correctly.
AIX has CDS disabled, it is currently not supported.