[lkml]   [2011]   [Mar]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH 0/6] get rid of on-stack dma buffers
    From: James Bottomley <>
    Date: Tue, 22 Mar 2011 08:35:04 -0500

    > The API will round up so that the correct region covers the API.
    > However, if you have other structures packed into the space (as very
    > often happens on stack), you get cache line interference in the CPU if
    > they get accessed: The act of accessing an adjacent object pulls in
    > cache above your object and destroys DMA coherence. This is the
    > principle reason why DMA to stack is a bad idea.

    Another major real reason we can't DMA on-stack stuff is because the
    stack is mapped virtually on some platforms.

    And that is the original reason the restriction was put in place.

     \ /
      Last update: 2011-03-22 21:17    [W:0.018 / U:8.128 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site