cdc driver debugging

Default setup:
    | |   |   +-o Black Magic Probe@fd130000  <class IOUSBDevice, id 0x10000ec55, registered, matched, active, busy 0 (1328 ms), retain 12>
    | |   |     +-o AppleUSBCDC  <class AppleUSBCDC, id 0x10000ec58, registered, matched, active, busy 0 (1 ms), retain 5>
    | |   |     +-o Black Magic GDB Server@0  <class IOUSBInterface, id 0x10000ec59, registered, matched, active, busy 0 (249 ms), retain 8>
    | |   |     | +-o AppleUSBCDCACMControl  <class AppleUSBCDCACMControl, id 0x10000ec5f, registered, matched, active, busy 0 (1 ms), retain 5>
    | |   |     +-o IOUSBInterface@1  <class IOUSBInterface, id 0x10000ec5a, registered, matched, active, busy 0 (252 ms), retain 8>
    | |   |     | +-o AppleUSBCDCACMData  <class AppleUSBCDCACMData, id 0x10000ec63, !registered, !matched, active, busy 0 (2 ms), retain 5>
    | |   |     |   +-o IOModemSerialStreamSync  <class IOModemSerialStreamSync, id 0x10000ec64, registered, matched, active, busy 0 (2 ms), retain 5>
    | |   |     |     +-o IOSerialBSDClient  <class IOSerialBSDClient, id 0x10000ec65, registered, matched, active, busy 0 (1 ms), retain 4>
    | |   |     +-o Black Magic UART Port@2  <class IOUSBInterface, id 0x10000ec5b, registered, matched, active, busy 0 (264 ms), retain 8>
    | |   |     | +-o AppleUSBCDCACMControl  <class AppleUSBCDCACMControl, id 0x10000ec67, registered, matched, active, busy 0 (1 ms), retain 5>
    | |   |     +-o IOUSBInterface@3  <class IOUSBInterface, id 0x10000ec5c, registered, matched, active, busy 0 (279 ms), retain 8>
    | |   |     | +-o AppleUSBCDCACMData  <class AppleUSBCDCACMData, id 0x10000ec6b, !registered, !matched, active, busy 0 (2 ms), retain 5>
    | |   |     |   +-o IOModemSerialStreamSync  <class IOModemSerialStreamSync, id 0x10000ec6c, registered, matched, active, busy 0 (2 ms), retain 5>
    | |   |     |     +-o IOSerialBSDClient  <class IOSerialBSDClient, id 0x10000ec6d, registered, matched, active, busy 0 (1 ms), retain 4>
    | |   |     +-o Black Magic Firmware Upgrade@4  <class IOUSBInterface, id 0x10000ec5d, registered, matched, active, busy 0 (275 ms), retain 6>

AppleUSBCDC driver unloaded:
    | |   |   +-o Black Magic Probe@fd130000  <class IOUSBDevice, id 0x10000ec9c, registered, matched, active, busy 0 (1633 ms), retain 12>
    | |   |     +-o IOUSBCompositeDriver  <class IOUSBCompositeDriver, id 0x10000ec9e, !registered, !matched, active, busy 0, retain 4>
    | |   |     +-o Black Magic GDB Server@0  <class IOUSBInterface, id 0x10000ec9f, registered, matched, active, busy 0 (251 ms), retain 6>
    | |   |     +-o IOUSBInterface@1  <class IOUSBInterface, id 0x10000eca0, registered, matched, active, busy 0 (598 ms), retain 6>
    | |   |     +-o Black Magic UART Port@2  <class IOUSBInterface, id 0x10000eca1, registered, matched, active, busy 0 (262 ms), retain 6>
    | |   |     +-o IOUSBInterface@3  <class IOUSBInterface, id 0x10000eca2, registered, matched, active, busy 0 (254 ms), retain 6>
    | |   |     +-o Black Magic Firmware Upgrade@4  <class IOUSBInterface, id 0x10000eca3, registered, matched, active, busy 0 (257 ms), retain 6>