lkml.org 
[lkml]   [2001]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: alpha iommu fixes
    At 1:28 PM -0700 2001-05-22, Richard Henderson wrote:
    >On Tue, May 22, 2001 at 05:00:16PM +0200, Andrea Arcangeli wrote:
    >> I'm also wondering if ISA needs the sg to start on a 64k boundary,
    >
    >Traditionally, ISA could not do DMA across a 64k boundary.
    >
    >The only ISA card I have (a soundblaster compatible) appears
    >to work without caring for this, but I suppose we should pay
    >lip service to pedantics.

    64KB for 8-bit DMA; 128KB for 16-bit DMA. It's a limitation of the
    legacy third-party-DMA controllers, which had only 16-bit address
    registers (the high part of the address lives in a non-counting
    register). This doesn't apply to bus-master DMA, just the legacy
    (8237) stuff. There was also a 24-bit address limitation.
    --
    /Jonathan Lundell.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 12:53    [W:0.042 / U:31.208 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site