mjg@ reports: # dtrace -n 'fbt::zfs_freebsd_fsync:entry { @[args[0]->a_vp] == count(); }' dtrace: invalid probe specifier fbt::zfs_freebsd_fsync:entry { @[args[0]->a_vp] == count(); }: internal error -- token type 316 is not a valid D compilation token The problem is "==" instead of "=" but dtrace should produce a proper error message.