[wdmaudiodev] Re: Overriding IRP_MJ_DEVICE_CONTROL handling is possible?

  • From: "Don Bell" <0dbell@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 10 Apr 2007 11:09:29 -0500

Thank you all for your help and tips in the matter - they were all
very helpful. The code snippet provided by Cheng-mean Liu was
especially helpful.

Cheng-mean Liu, I have one more question related to the example you
brought here:

  // gPrivateInterfaceRefStringCmp is your prviate interface
  // string that you register through IoRegisterDeviceInterface()
  // in the AddDevice() routine

In a "low level" WDM driver, I would of course use
IoRegisterDeviceInterface() to register the device interface. Thanks
to the book that I have, I also know that it should be done *after
creating* the device, but *before attaching* it to the device stack.

Which brings a question similar to the one asked by Tom: Does
IoRegisterDeviceInterface() really fit into the PortCls scheme?

That is, in PortCls we issue a single call to PcAddAdapterDevice()
which already takes care of attaching the device object to the device
stack. Thus, even if it is OK to call IoRegisterDeviceInterface() in
AddDevice(), it is certainly illegal to call it *after*
PcAddAdapterDevice(). Did I get this right? If not, what am I missing?

Does PcAddAdapterDevice() also takes care of registering a device
interface? I know that it registers *subdevices* (via StartDevice's
PcRegisterSubdevice) but does this come in place of the overall device
interface or in addition to it? As you can see here, I am pretty

And lastly, provided that I can register as many device interfaces as
I want (*before* calling PcAddAdapterDevice()), *must* I register a
new interface in order to handle custom IRP_MJ_DEVICE_CONTROL IOCTLs?
Or can I "reuse" one of the existing interfaces for that purpose?


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