On Mon, Feb 14, 2022 at 09:03:13AM -0400, Jason Gunthorpe wrote: > Groups should disappear into an internal implementation detail, not be > so prominent in the API. Not going to happen, IOMMU groups are ABI and todays device assignment code, including user-space, relies on them. Groups implement and important aspect of hardware IOMMUs that the API can not abstract away: That there are devices which share the same request-id. This is not an issue for devices concerned by iommufd, but for legacy device assignment it is. The IOMMU-API needs to handle both in a clean API, even if it means that drivers need to lookup the sub-group of a device first. And I don't see how a per-device API can handle both in a device-centric way. For sure it is not making it 'device centric but operate on groups under the hood'. Regards, Joerg
