I'm working of functional like USB device filtering. So it adds some restrictions I have to make a decision about plugged device before Start succeeds or fails IOUserClient, as I understood, used for App<->DEXT communication, but not DEXT<->DEXT. Am I right? Conceptually, I need some way to prepare IOService kind of IOResources that starts on DEXT bootstrap and can be reached within the App each time USB device is connected, I need to obtain set of rules to filter particular USB device/interface. This can be achieved by communicating inside DEXT if I could have such mechanism