On Thu, Jan 20, 2022 at 02:56:02PM +0100, Christoph Hellwig wrote:
- on the input side to dma mapping the bio_vecs (or phyrs) are chained
as bios or whatever the containing structure is. These already exist
and have infrastructure at least in the block layer
- on the output side I plan for two options:
1) we have a sane IOMMU and everyting will be coalesced into a
single dma_range. This requires setting the block layer
merge boundary to match the IOMMU page size, but that is
a very good thing to do anyway.
It doesn't look like IOMMU page sizes are exported, or even necessarily
consistently sized on at least one arch (power).