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    SubjectRe: [PATCHSET] block: fix PIO cache coherency bug, take 2
    On Mon, Jun 05, 2006 at 10:47:40AM -0500, James Bottomley wrote:
    > On Mon, 2006-06-05 at 16:34 +0100, Russell King wrote:
    > > What has zero copy (your reply) got to do with faulting pages into
    > > userspace (my message). I'm sorry, I don't understand why you've
    > > brought this up.
    >
    > The zero copy case is the case where we end up with user and kernel
    > mappings simultaneously on the page. The nopage (or fault) case is
    > where we end up with them sequentially. Both cases actually require the
    > same cache treatment, but it's easiest to understand in the zero copy
    > case.

    When does the zero copy case occur?

    --
    Russell King
    Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
    maintainer of: 2.6 Serial core
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