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All of the iommu drivers setup an iommu translation and enable ATS before any driver is bound. We would need to do more work in the core to leave the translation blocked when there is no driver. I don't think it is that difficult > > Drivers need to ensure that ATS is disabled at PCI and Translated > > requestes blocked in IOMMU HW while a BLOCKED domain is attached. > > "Drivers" here meaning IOMMU drivers, right? Yes Jason