Messages in this thread | | | From | Bret Indrelee <> | Subject | PCI DMA question | Date | Fri, 29 Oct 1999 14:27:38 -0500 |
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I've come across something that I would like someone to verify.
It appears that the standard linux kernel lacks a way for a character driver to DMA data directly to the user buffer.
I was searching for the way to lock pages into memory. This eventually lead me to the following patch, which doesn't appear to have been added to the standard kernel at any point: http://linux-patches.rock-projects.com/v2.2-f/userdma-2.2.5.html
I've also found partial messages where David S. Miller and Linus were discussing the need for this (Linus mentioned dma_map()), but I couldn't find enough of the discussion to know if anything was implemented or not.
Since I've got a device that is quite capable of scatter-gather and have no interest in double copying, it appears that I will need this patch in order to get reasonable performance.
Is something like this in the 2.3 kernel, or is this yet another patch that didn't get accepted?
-Bret
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Bret Indrelee, Engineer SBS Technologies, Inc., Connectivity Products 1284 Corporate Center Drive, St. Paul MN 55121 Direct: (651) 905-4731 Main: (651) 905-4700 Fax: (651) 905-4701 E-mail: bindrelee@sbs-cp.com http://www.sbs.com -------------------------------------------------------------
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