Make sure that the driver only exists when all it's threads are dead. (Rev 334)
drwxr-xr-x - core
-rw-r--r-- 52 dirs
drwxr-xr-x - hw
drwxr-xr-x - inc
drwxr-xr-x - tests
drwxr-xr-x - tools
drwxr-xr-x - ulp