On Thu, Apr 21, 2022 at 9:20 AM Christoph Hellwig [off-list ref] 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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel