The system property sun.boot.class.path will not be available in JDK 9. The Hotspot agent has 3 uses of this property in the following files that should be reviewed and potentially removed.
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/jdi/VirtualMachineImpl.java: return getPath("sun.boot.class.path");
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/soql/JSJavaVM.java: return vm.getSystemProperty("sun.boot.class.path");
src/jdk.hotspot.agent/test/jdi/runsa.sh: -Dsun.boot.class.path=$jdk/classes \