On Mon, Aug 15, 2022 at 11:14:33AM -0700, Nicolin Chen wrote: > Provide a dedicated errno from the IOMMU driver during attach that the > reason attached failed is because of domain incompatability. EMEDIUMTYPE > is chosen because it is never used within the iommu subsystem today and > evokes a sense that the 'medium' aka the domain is incompatible. I am not a fan of re-using EMEDIUMTYPE or any other special value. What is needed here in EINVAL, but with a way to tell the caller which of the function parameters is actually invalid. For that I prefer adding an additional pointer parameter to the attach functions in which the reason for the failure can be communicated up the chain. For the top-level iommu_attach_device() function I am okay with having a special version which has this additional paremter. Regards, Joerg
