Prevent PDO from becoming a phantom device after parent is removed

NTDEV
1

Disclaimer: This is for a hobby project, this isnt for work ?. I am a beginner when it comes to driver development.

I have a kmdf wdf driver that is root enumerated and behaves kind of like a bus or fdo. It creates a pdo when it gets installed via devcon for now.
After it is installed it creates a pdo. This works. But when I remove my driver the pdo does not get removed properly but keeps its registry entries and therefore becomes a non-present aka a phantom device. Since this phantom device allocates a com number this is really annoying since I always have to remove it manually. Is there a way to force the removal of a pdo? I already tried both static enumeration with wdfpdomarkmissing on EvtDeviceReleaseHardware and dynamic enumeration using WdfChildListRequestChildEject. Both of them are not working.

2

One thing you could do is install your driver with a proper installer. During uninstall make a custom action that calls DIF_REMOVE for each of your devices you want to forcefully remove.

3

How do you create your PDO? You said you’re using KMDF. If you’re using the provided WdfChildList APIs, then it is your responsibility at unplug time to call WdfChidListBeginScan/WdfChlidListEndScan, which tells the system “I have no child PDOs”.

4

Yeah that is exactly what I am doing. If for example I do this during an ioctl request, the pdo get’s “unplugged” too. But it just gets grayed out (becomes a phantom device). I want it removed from the registry completely.