[wdmaudiodev] IPortWaveRTStream::AllocateContiguousPagesForMdl problem in Windows 7
- From: "Jeff Pages" <jeff@xxxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Fri, 13 Mar 2009 09:57:19 +1100
I'm testing our WaveRT drivers on the x64 beta release of Windows 7, and am
finding that IPortWaveRTStream::AllocateContiguousPagesForMdl frequently (but
not always) returns NULL even when the amount of memory requested is less than
one page, whereas IPortWaveRTStream::AllocatePagesForMdl always succeeds.
In this particular scenario, I'm allocating memory for the descriptor table I
need to pass to my scatter-gather hardware, and while it's mostly much less
than one page long, there's a possibility with high sampling rates, extended
bit depths and a large buffer that it could end up longer than a page, which is
why I'm using AllocateContiguousPagesForMdl. This works fine under Vista.
Is there any reason not to use AllocateContiguousPagesForMdl for allocations
that might be smaller than one page?
Jeff
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