Running the VM with e.g.
java -XX:NonNMethodCodeHeapSize=1200K -X:+UseTransparentHugePages -version

will result in
uintx NonNMethodCodeHeapSize=0 is outside the allowed range [ 4096 ... 18446744073709551615 ]
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (jvmFlagAccess.cpp:70), pid=123765, tid=123768
# fatal error: FLAG_SET_ERGO cannot be used to set an invalid value for NonNMethodCodeHeapSize
#

This happens when the page size is larger than the code heap segment size. Then align_down will reduce the size value to 0 and continue to call FLAG_SET_ERGO with this invalid value.

The proposed solution is to set the non nmethod code heap size to the minimal possible size when validating the parameter.