[libvirt] question about PCI new_id sysfs interface

[Daniel P. Berrange]

On Wed, Jun 29, 2016 at 08:00:22AM -0600, Alex Williamson wrote:
> On Wed, 29 Jun 2016 09:47:55 +0100
> "Daniel P. Berrange" <berrange at redhat.com> wrote:
> 
> > 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
> 
> I don't think this is a reasonable demand.  For one, the change was
> made 2yrs ago and nobody noticed until now, I don't think there are
> stable kernel releases to cover all those kernels.  There must be some
> sort of statute of limitations.

Oh sorry, I totally missed the date on that. I was thinking this was a
recent kernel regression. I agree that if 2+ years have passed, this
ship has sailed.

Regards,
Daniel
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