On Mon, Apr 13, 2020 at 04:21:29PM -0600, Alex Williamson wrote: > Is the objection to a global version or to any version fields? I don't > really understand the global version, I'd think a mechanism to check > extensions plus a per structure flags/version would be preferred. The > former should resolve how userspace can test support for features > requiring multiple interfaces. A global version also implies that > we're only ever adding features and never removing. For example, > feature Foo is added in version 4, but it's replaced by feature Bar in > version 5, now userspace can't simply test version >= 4 must include > feature Foo.
The objection is to versions vs the much more sensible struct size + capability flags. Making it global just increases the problems with a version for all of the above reasons. > It seems to me that version and flags can also be complimentary, for > example a field might be defined by a version but a flag could indicate > if it's implemented. With only the flag, we'd infer the field from the > flag, with only the version we'd need to assume the field is always > implemented. So I have a hard time making a blanket statement that all > versions fields should be avoided. s/version/struct size/, but otherwise agreed. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
