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

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Mon, 18 May 2020 13:36:58 -0700

(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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