Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 3 Jan 2018 08:49:35 +0100 | Subject | Re: [PATCH 16/67] powerpc: rename dma_direct_ to dma_nommu_ |
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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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