On Thu, Apr 21, 2022 at 9:20 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> Btw, there is another option: Most real systems already require having
> swiotlb to bounce buffer in some cases. We could simply force bounce
> buffering in the dma mapping code for too small or not properly aligned
> transfers and just decrease the dma alignment.
I like the idea because these days we already rely on bounce buffering
for sub-page buffers in many iommu based cases for strict isolation
purposes, as well as most 64-bit machines that lack an iommu.
Does this work on all 32-bit architectures as well? I see that you added
swiotlb for ARM LPASE systems in 2019, but I don't know if that has any
additional requirements for the other 32-bit architectures that don't
select SWIOTLB today.
Arnd
