Messages in this thread | | | Date | Wed, 1 Oct 2014 11:05:13 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 0/5] enhance DMA CMA on x86 |
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On Tue, 30 Sep 2014, Peter Hurley wrote: > On 09/30/2014 07:45 PM, Thomas Gleixner wrote: > > Whether the proposed patchset is the correct solution to support it is > > a completely different question. > > This patchset has been in mainline since 3.16 and has already caused > regressions, so the question of whether this is the correct solution has > already been answered.
Agreed.
> > So either you stop this right now and help Akinobu to find the proper > > solution > > If this is only a test platform for ARM parts then I don't think it > unreasonable to suggest forking x86 swiotlb support into a iommu=cma > selector that gets DMA mapping working for this test platform and doesn't > cause a bunch of breakage.
Breakage is not acceptable in any case.
> Which is different than if the plan is to ship production units for x86; > then a general purpose solution will be required. > > As to the good design of a general purpose solution for allocating and > mapping huge order pages, you are certainly more qualified to help Akinobu > than I am.
Fair enough. Still this does not make the case for outright rejecting the idea of supporting that kind of device even if it is a esoteric case. We deal with enough esoteric hardware in Linux and if done right, it's no harm to anyone.
I'll have a look at the technical details.
Thanks,
tglx
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