A blocker issue for jigsaw/m2 going into JDK 9 is that bootcycle builds must be working. Currently bootcycle builds are failing in JPRT. It's possible that this will require both build and javac changes, maybe jrt changes too.

Here is a fragment of a typical log:

:
Warning: reference to bootmodules.jimage replaced by jrt:
Warning: reference to /opt/jprt/T/P1/100301.albatem/s/build/linux-x86-normal-clientANDserver-release/images/jdk/lib/modules/appmodules.jimage ignored
Warning: reference to bootmodules.jimage replaced by jrt:
Warning: reference to /opt/jprt/T/P1/100301.albatem/s/build/linux-x86-normal-clientANDserver-release/images/jdk/lib/modules/appmodules.jimage ignored
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors
gmake[4]: *** [/opt/jprt/T/P1/100301.albatem/s/build/linux-x86-normal-clientANDserver-release/bootcycle-build/buildtools/corba_interim_classes/_the.BUILD_INTERIM_CORBA_batch] Error 1
gmake[4]: Leaving directory `/opt/jprt/T/P1/100301.albatem/s/corba/make'
gmake[3]: *** [interim-corba] Error 2
gmake[3]: *** Waiting for unfinished jobs....