[wdmaudiodev] Re: Issue with using a compiled ac97 audio driver from the sample code

  • From: "" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "zero3k" for DMARC)
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 20 May 2020 00:31:40 +0000

I can see the register values via WinDbg. Which ones should I look at?

May 18, 2020 4:37 PM, "Tim Roberts" <timr@xxxxxxxxx> wrote:

(Redacted sender zero3k for DMARC) wrote:

Oh, how do I do one or both of the things mentioned in
https://boards.4channel.org/wsr/thread/816097#p817255 ? Maybe doing either ;
of those will lead to
the reason for the issue.

I see the reactions and responses to your requests over there was pretty
similar to my reactions here.

Here are the facts,  The AC97 sample is known to work on AC97 hardware. 
If it doesn't work with VirtualBox's fake device, then the fake device
doesn't work like the hardware.  The sample is post-Vista, so it expects
the new Audio Engine.  WS2003 is pre-Audio Engine.   I diffed the AC97
sample between the 8.1 WDK and the Server 2003 DDK, and the only
difference is that the 8.1 version tries for a WaveRT connection before
trying WavePCI, whereas WaveRT is not available prior to Vista.

DMA problems are among the hardest to debug.  As suggested, you'll need
to add some debug prints ("breadcrumbs") to show you what the register
values are.  If the current pointer is truly outside of the circular
buffer, then you just need to back up until you find out why.

Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.


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