Messages in this thread | | | Date | Tue, 10 Oct 2023 10:40:44 +0100 | Subject | Re: [PATCH v2] dma-mapping: fix dma_addressing_limited if dma_range_map can't cover all system RAM | From | Robin Murphy <> |
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On 2023-10-10 08:48, Christoph Hellwig wrote: > dma_addressing_limited is called for every dma (direct) map, and this > new code is way to heavy for that. We'll need to cache the information > somehow.
But is it? That was my instinctive reaction as well, but AFAICS it is only actually used by drivers in setup paths, either directly or via dma_max_mapping_size(). The dma_capable() check which we *do* use for every actual mapping still just checks whether the given physical address exists in the range map. I believe the underlying problem here is when dma_capable() say the mapping needs bouncing, but then it's too big for that to succeed, since dma_max_mapping_size() gave the wrong answer to start with.
Thanks, Robin.
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