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    SubjectPCI DMA question
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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

    -------------------------------------------------------------
    SBS Technologies, Connectivity Products
    ... solutions for real-time connectivity

    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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