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    SubjectRe: [PATCH v2 3/6] x86, mm, asm-gen: Add ioremap_wt() for WT
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    On Wed, 2014-09-10 at 11:29 -0700, Andy Lutomirski wrote:
    > On Wed, Sep 10, 2014 at 9:51 AM, Toshi Kani <toshi.kani@hp.com> wrote:
    :
    > > +#ifndef ARCH_HAS_IOREMAP_WT
    > > +#define ioremap_wt ioremap_nocache
    > > +#endif
    > > +
    >
    > This is a little bit sad. I wouldn't be too surprised if there are
    > eventually users who prefer WC or WB over UC if WT isn't available
    > (and they'll want a corresponding way to figure out what kind of fence
    > to use).

    Right, this redirection is not ideal for the performance, but it is done
    this way for the correctness. WT & UC have strongly ordered writes, but
    WB & WC do not.

    Thanks,
    -Toshi



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