Sorry, it is a bit confusing as we aren't quite done with the transition
from an older form of a -Xpatch to the new form.
The syntax you see in JEP 261 and in the java -X usage output is the new
form. That works for modules defined to the platform or application
class loaders but doesn't work for modules (like java.base) that are
defined to the boot loader. Lois is working on the missing piece in
hotspot, it is tracked by JDK-8146448. All the other pieces (in javac
and the runtime) are in place.
In the mean-time, the old form still works. The old syntax is
-Xpatch:<dir>(:<dir>*) where <dir> is a directory of exploded patches.
If you want to override CHM then you would run with -Xpatch:jsr166 where
jsr166 contains:
java.base/java/util/concurrent/ConcurrentHashMap.class
You can use the old syntax with the first usage of -Xpatch, not second
or subsequent usages. That is why you see a difference in the
-Xpatch:junk behavior when you specify it more than once.
-Alan.
