@rbernon I'm okay with using reserved as an offset to pass the device path, but we'd still have to pass it for every message for filtering. I didn't want to utilize `reserved` mostly out of caution, if it ever turned out to be that the field did have some undocumented semantics after all.
Maybe we can avoid sending the paths every time by moving the filtering to plugplay, adapting the interface a bit for this. There could be additional methods to register paths / get plugplay handles in return, and later use these handle as device handles.