Messages in this thread | | | Date | Mon, 19 Nov 2018 16:48:02 -0800 (PST) | Subject | Re: [PATCH 2/2] arch: switch the default on ARCH_HAS_SG_CHAIN | From | Palmer Dabbelt <> |
| |
On Mon, 19 Nov 2018 05:58:52 PST (-0800), Christoph Hellwig wrote: > On Fri, Nov 16, 2018 at 08:52:14AM -0800, Palmer Dabbelt wrote: >> As far as I can tell, it looks like m68k, mips, and powerpc mention an >> IOMMU in their ports, don't set ARCH_HAS_SG_CHAIN, and with this patch set >> won't set ARCH_NO_SG_CHAIN. > > m68k has no iommu, and not operations that operate on a scatterlist. > > mips has a trivial iommu driver (jazzdma), but I wrote the current > instance of it, nad it is fine. > > powerpc has various iommu, but actually enables ARCH_HAS_SG_CHAIN > unconditionally. > >> The issue is that I'm not sure how to >> determine what constitutes a horrible legacy IOMMU, at least with respect >> to not being able to use scatterlist chaining. > > It basically means someone is iterating using manual pointer arithmetics > over a multi-element scatterlist instead of using the sg_next and > for_each_sg helpers.
Ah, OK. In that case, feel free to drop a
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
in there, if you think it helps any.
Thanks for the help!
| |