I noticed I couldn't use an exploded jdk tarball because some files were not world readable. tar tvzf jdk-9-ea+153_linux-x64_bin.tar.gz ... -rw-r--r-- java_re/java_re 73955 2017-01-18 17:59 jdk-9/include/jni.h -rw-r--r-- java_re/java_re 824 2017-01-18 17:59 jdk-9/include/linux/jni_md.h -rw-r--r-- java_re/java_re 968 2017-01-18 17:59 jdk-9/include/linux/jawt_md.h -rw------- java_re/java_re 535839 2017-01-18 17:59 jdk-9/jmods/jdk.jshell.jmod -rw------- java_re/java_re 2116660 2017-01-18 17:59 jdk-9/jmods/jdk.plugin.jmod -rw------- java_re/java_re 119739 2017-01-18 17:59 jdk-9/jmods/java.logging.jmod -rw------- java_re/java_re 131409 2017-01-18 17:59 jdk-9/jmods/jdk.jdwp.agent.jmod -rw------- java_re/java_re 23723724 2017-01-18 17:59 jdk-9/jmods/javafx.web.jmod
A final step in building files suitable for distribution is chmod -R a+rX
