Re: kvm PCI assignment & VFIO ramblings

[David Gibson <dwg@au1.ibm.com>]

On Wed, Aug 24, 2011 at 11:14:26AM +0200, Roedel, Joerg wrote:
> On Tue, Aug 23, 2011 at 12:54:27PM -0400, aafabbri wrote:
> > On 8/23/11 4:04 AM, "Joerg Roedel" <joerg.roedel@amd.com> wrote:
> > > That is makes uiommu basically the same as the meta-groups, right?
> > 
> > Yes, functionality seems the same, thus my suggestion to keep uiommu
> > explicit.  Is there some need for group-groups besides defining sets of
> > groups which share IOMMU resources?
> > 
> > I do all this stuff (bringing up sets of devices which may share IOMMU
> > domain) dynamically from C applications.  I don't really want some static
> > (boot-time or sysfs fiddling) supergroup config unless there is a good
> > reason KVM/power needs it.
> > 
> > As you say in your next email, doing it all from ioctls is very easy,
> > programmatically.
> 
> I don't see a reason to make this meta-grouping static. It would harm
> flexibility on x86. I think it makes things easier on power but there
> are options on that platform to get the dynamic solution too.

I think several people are misreading what Ben means by "static".  I
would prefer to say 'persistent', in that the meta-groups lifetime is
not tied to an fd, but they can be freely created, altered and removed
during runtime.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson