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    SubjectRe: [PATCH v2] dma-mapping: fix dma_addressing_limited if dma_range_map can't cover all system RAM
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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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