DMA Question

In the DDK docs about the GetScatterGatherList function is written, that
it may wait until map registers are available.
In the driver I write would like to allocate the map registers earlier
(prepare the buffers to be transferred), then fill the buffers with data
and transfer immediately (without potential waiting for map registers).
Is this possible? can the buffers still be accessed after the map
registers are assigned?
I do know the exact buffer size before the data is available.

Ralf Findeisen


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Take a look at an article in NT Insider titled “Extreme DMA”. It discusses a
technique for queuing requests within the callback function of
GetScatterGatherList if the device is busy.

(Disclaimer for Greg Dyess: Using this technique can severely impact the
performance of DMA in other systems.) (Ahhh you folks just know dat da devil
made me do it! :))

Gary G. Little
Staff Engineer
Broadband Storage, Inc.
xxxxx@broadstor.com

-----Original Message-----
From: Ralf Findeisen [mailto:xxxxx@amd.com]
Sent: Tuesday, August 07, 2001 5:58 AM
To: NT Developers Interest List
Subject: [ntdev] DMA Question

In the DDK docs about the GetScatterGatherList function is written, that
it may wait until map registers are available.
In the driver I write would like to allocate the map registers earlier
(prepare the buffers to be transferred), then fill the buffers with data
and transfer immediately (without potential waiting for map registers).
Is this possible? can the buffers still be accessed after the map
registers are assigned?
I do know the exact buffer size before the data is available.

Ralf Findeisen


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To unsubscribe send a blank email to leave-ntdev-$subst(‘Recip.MemberIDChar’)@lists.osr.com


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