[wdmaudiodev] Re: Where did the MSVAD GUIDs disappear?
- From: Tim Roberts <timr@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Thu, 12 Apr 2007 15:55:02 -0700
Don Bell wrote:
> On 4/10/07, Don Bell <0dbell@xxxxxxxxx> wrote:
>
>> 1. Do audio miniport drivers register interfaces at all?
>
>> From the WDM Audio Terminology section in the WDK documentation:
>
> "The port class driver's PcRegisterSubdevice function registers the
> subdevice, which is *perceived as a device* by the rest of the
> system."
>
> However, a few paragraphs earlier, in the definition of "Miniport
> Driver (WDM Audio)" one can find:
>
> "It [The miniport driver] is not recognized as a driver by the
> operating system."
>
> Interesting subtlties to notice here: Subdevice gets registered, but
> not the miniport drivers.
Yes. A device and a driver are two very different things. A driver is
an executable that can be loaded into memory and run, and which provides
services to the system. A device is a virtual thing -- a data
structure that the operating system uses to gain access to the services
provided by a driver. You can't talk to a driver, except by going
through a device.
A WDM audio miniport is not recognized as a driver by the operating
system, because it is not a standalone unit. It and the adapter driver
are linked together into one larger DLL, and that combined unit is
recognized as a driver by the operating system.
Many of the terms in the DDK world are overloaded multiple times, which
is why these terminology pages are so critical. Perhaps the worst
example is "filter"...
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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