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AFAICR the biggest issue with arm-smmu was it using IO_PGTABLE_ARMV7S as well. I think it would be fine to implement all the unique LPAE features it needs in iommupt, I did most of them already. I do have an ARMV7S implementation for iommupt, but I did not solve the sub page problem. So while it is functionally working it is not usable since it wastes so much memory. That's a tricky problem to solve since the algorithms depend on the gather->freelist. I didn't spend any time trying to do anything about this as I was not intending to touch arm-smmu Jason