Re: [PATCH] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Apr 20, 2020 at 10:24:59AM +0100, Daniel P. Berrangé wrote:
> On Fri, Apr 17, 2020 at 12:09:00PM -0400, Michael S. Tsirkin wrote:
> > On Fri, Apr 17, 2020 at 03:36:14PM +0000, Ani Sinha wrote:
> > > 
> > > 
> > > > On Apr 17, 2020, at 8:57 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > 
> > > > Is there a real reason to do this? Can't we just limit the
> > > > hotplug control to pcie ports? At some point I'd like us to
> > > > start leaving piix alone..
> > > 
> > > Yes we really need this feature as want to be able to hot plug devices into the guest but prevent customers from hot unplugging them from say Windows system tray.
> > > 
> > > ani
> > 
> > Problem is, I think this is not something we can support with pcie or shpc.
> > I'm reluctant to add features that only ACPI can support,
> > we are trying to phase that out.
> 
> >From the upstream POV, there's been no decision / agreement to phase
> out PIIX,

Phase out now.  But I for one would like to focus on keeping PIIX stable
and focus development on q35.  Not bloating PIIX with lots of new
features is IMHO a good way to do that.



> this is purely a RHEL downstream decision & plan. If other
> distros / users have a different POV, and find the feature useful, we
> should accept the patch if it meets the normal QEMU patch requirements.
> 
> Regards,
> Daniel

Orthogonality of features is important. It is tough to navigate our
feature matrix as it is. Figuring things out if random features
depend on other random features becomes impossible.


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