Hi All, On Wed, Jan 3, 2018 at 6:49 PM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > Hi Michael, > > On Wed, Jan 3, 2018 at 7:24 AM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote: >> Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes: >> >>> On Tue, Jan 2, 2018 at 10:45 AM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote: >>>> Christoph Hellwig <hch@xxxxxx> 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? If this is indeed a linear mapping, can we just remove this and replace it with the new "generic" mapping being introduced by this patchset? Thanks, -- Julian Calaby Email: julian.calaby@xxxxxxxxx Profile: http://www.google.com/profiles/julian.calaby/
