[libvirt] question about PCI new_id sysfs interface

[Daniel P. Berrange]

On Tue, Jun 28, 2016 at 02:30:47PM -0400, Bandan Das wrote:
> "Daniel P. Berrange" <berrange at redhat.com> writes:
> 
> > Adding Alex & Bandan, since they signed off the kernel patch which
> > I'm thinking either pci-back should be made to work more like
> > vfio, or the kernel patch should be reverted or fixed to take
> > account of the way pci-back works.
> >
> > Whichever way, I don't consider this a libvirt problem to solve. As
> > Linus' always says - the kernel must never break existing userspace
> 
> Agreed, but in this specific case, the usage is unsafe since unknown indexes
> are potentially being passed to the driver operations. It should always have been
> 3. to begin with.

Whether the userspace usage is good or not is irrelevant - this kernel change
has broken existing userspace apps and that is not acceptable and must be fixed.

I'm fine with suggestions to change future libvirt to work in a better way,
but we need to fix the regressions seen by *current* libvirt releases


Regards,
Daniel
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