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    SubjectRe: pci-sysfs resource mmap broken (and PATCH)
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    On Thu, 2005-04-28 at 00:22 -0700, David S. Miller wrote:
    > On Thu, 28 Apr 2005 17:21:19 +1000
    > Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
    >
    > > I have a real net big performance improvement on X by doing that
    > > trick ... the sysfs mmap API doesn't really provide a mean to do
    > > it explicitely from userland (unlike the ioctl with the old proc api)
    >
    > You can refine your test to "if PCI class is display or VGA" and the
    > prefetchability is set in the BAR, then elide the guard PTE
    > protection bit.

    Yes, but I was also thinking about some of those Myrinet kind of things
    who also provide large PCI shared memory region ...

    I may end up adding an explicit list of classes/vid/did that are
    "allowed" to use the trick to avoid problems.

    Ben.


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