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Why is my PCI driver's enumerator is “ROOT”?

EladMEladM Member Posts: 2
edited March 2020 in NTDEV

Hi all,

I am trying to write my first driver for a PCI device using WDF.

I took the basic kmdf project template from Visual Studio, added a few relevant empty PNP callbacks, debug tracing and edited the .inf file to include the hardware id for the connected PCI device.

From the .inf file:

%cvbkmd.DeviceDesc%=cvbkmd_Device, PCI\VEN_1172&DEV_424F; hw-id

Once I install the driver via the devcon tool, I can see something weird happening:

After a few hiccups in device manager, I can see 2 device instances under the same device class. one is a software driver (sits under ROOT) and the other is a proper PCI device.

Watching the driver debug traces in TraceView, I can see that all device event callbacks are called twice. once for each enumerator. when they are called with by the PCI enumerator, I get the parameters I expect from the PCI device. For example EVT_WDF_DEVICE_PREPARE_HARDWARE callback is called once with an empty TranlatedResources list and once with the PCI device resources as I would expect.

I tried to perform a windows restore and re-install the driver, but the problem still exists.

So what can cause my device being installed under ROOT?


  • Doron_HolanDoron_Holan Member - All Emails Posts: 10,600

    "devcon install" will create a root enumerated device. you should only use "devcon update" to install your driver on the PCI enumerated device. You can safely delete the root enumerated device via device manager.

  • Tim_RobertsTim_Roberts Member - All Emails Posts: 13,972

    "devcon install" is perhaps the most deceiving command ever invented. The oh-so-inviting name fools people into believing it does things that it doesn't really do. In retrospect, maybe "devcon create" would have been a better choice.

    Tim Roberts, [email protected]
    Providenza & Boekelheide, Inc.

  • EladMEladM Member Posts: 2


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