On Tue, Aug 23, 2011 at 02:54:43AM -0400, Benjamin Herrenschmidt wrote:

Possibly, the question that interest me the most is what interface will
KVM end up using. I'm also not terribly fan with the (perceived)
discrepancy between using uiommu to create groups but using the group fd
to actually do the mappings, at least if that is still the plan.

If the separate uiommu interface is kept, then anything that wants to be
able to benefit from the ability to put multiple devices (or existing
groups) into such a "meta group" would need to be explicitly modified to
deal with the uiommu APIs.

I tend to prefer such "meta groups" as being something you create
statically using a configuration interface, either via sysfs, netlink or
ioctl's to a "control" vfio device driven by a simple command line tool
(which can have the configuration stored in /etc and re-apply it at
boot).

Hmm, I don't think that these groups are static for the systems
run-time. They only exist for the lifetime of a guest per default, at
least on x86. Thats why I prefer to do this grouping using VFIO and not
some sysfs interface (which would be the third interface beside the
ioctls and netlink a VFIO user needs to be aware of). Doing this in the
ioctl interface just makes things easier.

	Joerg

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