Re: [PATCH v3 0/5] enhance DMA CMA on x86

From: Peter Hurley
Date: Tue Sep 30 2014 - 21:50:34 EST

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.

> 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.

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.

Peter Hurley

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