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    SubjectRe: [PATCH 16/67] powerpc: rename dma_direct_ to dma_nommu_
    Hi Michael,

    On Wed, Jan 3, 2018 at 7:24 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
    > Geert Uytterhoeven <geert@linux-m68k.org> writes:
    >
    >> On Tue, Jan 2, 2018 at 10:45 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
    >>> Christoph Hellwig <hch@lst.de> writes:
    >>>
    >>>> We want to use the dma_direct_ namespace for a generic implementation,
    >>>> so rename powerpc to the second best choice: dma_nommu_.
    >>>
    >>> I'm not a fan of "nommu". Some of the users of direct ops *are* using an
    >>> IOMMU, they're just setting up a 1:1 mapping once at init time, rather
    >>> than mapping dynamically.
    >>>
    >>> Though I don't have a good idea for a better name, maybe "1to1",
    >>> "linear", "premapped" ?
    >>
    >> "identity"?
    >
    > I think that would be wrong, but thanks for trying to help :)
    >
    > The address on the device side is sometimes (often?) offset from the CPU
    > address. So eg. the device can DMA to RAM address 0x0 using address
    > 0x800000000000000.
    >
    > Identity would imply 0 == 0 etc.
    >
    > I think "bijective" is the correct term, but that's probably a bit
    > esoteric.

    OK, didn't know about the offset.
    Then "linear" is what we tend to use, right?

    Gr{oetje,eeting}s,

    Geert

    --
    Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

    In personal conversations with technical people, I call myself a hacker. But
    when I'm talking to journalists I just say "programmer" or something like that.
    -- Linus Torvalds

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