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    SubjectRe: How does ioremap() get non-cached mappings
    On Fri, 16 Apr 2004, Brian Gerst wrote:

    > Nagendra Singh Tomar wrote:
    > > ioremap() function in x86 arch code does not seem to be setting _PAGE_PCD
    > > bit in the PTE. How then does it give non-cached mapping to MMIO mappings
    > > for memory on some interface card. I have gone thru some old threads on
    > > this, which have concluded that it does give non-cached mappings, and
    > > moerover ioremap seems to work fine whenever I have used to map any PCI
    > > card memory,
    > > Is it guaranteed thru the means of MTRR ?
    > >
    >
    > ioremap_nocache()

    I'm aware of ioremap_nocache(), and the fact that it explicitly sets
    _PAGE_PCD. My question originated after reading this posting by Alan

    http://www.uwsg.iu.edu/hypermail/linux/kernel/0110.0/0878.html

    in which he explicitly states that ioremap() gives uncached mapping. If
    you follow the thread, there is a general consensus that ioremap and
    ioremap_nocache are functionaly the same on x86 arch (and I suppose on
    most archs)

    Thanx,
    tomar
    >
    > --
    > Brian Gerst
    >

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