Re: [PATCH v2 1/3] iommu/uapi: Define uapi version and capabilities

[Christoph Hellwig]

On Mon, Apr 13, 2020 at 01:41:57PM -0700, Jacob Pan wrote:
> Hi All,
> 
> Just a gentle reminder, any feedback on the options I listed below? New
> ideas will be even better.
> 
> Christoph, does the explanation make sense to you? We do have the
> capability/flag based scheme for IOMMU API extension, the version is
> mainly used for size lookup. Compatibility checking is another use of
> the version, it makes checking easy when a vIOMMU is launched.

No.  If you truely need different versions use different ioctl
identifiers.  If it really is just the size pass the size and not a
version.