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Hardware bugs / quirks. Some of the simpler ones could probably be > handled but for the more invasive stuff like the Mali format > format, io-pgtable will probably need to hang around. Perhaps > it becomes io-pgtable-mali.c? I briefly looked at Mali a while back and it didn't seem so bad, but that was for a GPU driver not the iommu so a bit different issue. Exactly what the GPU drivers should be doing is less clear to me, they don't really fit well with the iommu focused interface (eg the memory preload issues/etc). > 2. The pKVM work from Mostafa. We'll probably end up with something > separate at EL2 for this (ideally, just reusing the CPU page-table > code when it learns about BBML3). Yeah, I'm not sure here, it isn't great that is adding another user and open coding some of the logic (eg smmu_pgsize_idmap). It would be much better if it could just use all the existing flow more directly somehow. > 3. Non-coherent walkers, although I think this might actually be fine > because x86 needs it anyway? This is done already, the smmuv3 conversion I've posted supports it. > So, for now, I wouldn't require new drivers to use iommupt but I'm The recently posted broadcom driver used iommupt and I thought it turned out very clean, it actually seems like less work to do it this way than try to write your own page table like that rockchip driver did which required several review rounds. Jason