Re: [Qemu-devel] [Xen-devel] [PATCH] Citrix PV Bus device

[Ian Campbell]

On Tue, 2013-07-02 at 10:14 +0100, Paul Durrant wrote:
> > -----Original Message-----
> > From: Ian Campbell
> > Sent: 02 July 2013 09:57
> > To: Paul Durrant
> > Cc: address@hidden; address@hidden
> > Subject: Re: [Xen-devel] [PATCH] Citrix PV Bus device
> > 
> > On Tue, 2013-07-02 at 09:39 +0100, Paul Durrant wrote:
> > > This patch introduces a new PCI device which will act as the binding point
> > > for Citrix branded PV drivers for Xen.
> > > The intention is that Citrix Windows PV drivers will be available on 
> > > Windows
> > > Update and thus using the existing Xen platform PCI device as an anchor
> > > point is not desirable as that device has been ubiquitous in HVM guests 
> > > for
> > > a long time and thus existing HVM guests running Windows would start
> > > automatically downloading drivers from Windows Update when this may
> > not be
> > > desired by either the host or guest admin.
> > 
> > What about
> > <address@hidden>
> > ?
> > 
> 
> I had actually coded up a solution based on the existing Xen platform
> device, by having it synthesize a device ID based on the Xen version
> to which we could then host the xenbus driver, to allow us to deploy
> multiple versions of xenbus should compatibility (with things such as
> the shared info interface) become an issue. The co-installer for this
> driver could also spot existing PV driver installations and make sure
> they don't get trashed.

I think only this last bit of functionality is critical here, and it
allows us to avoid having to carry multiple platform devices in
upstream, doesn't it?

> This idea was rejected by Citrix product teams though, because we
> would not be able to prevent any Windows guest without some known PV
> drivers from downloading our new driver from Windows Update and this
> was seen as undesirable.

Well, if your product requirements are at odds with doing the right
thing upstream then I think it would be best for you to just carry
patches to make XS behave how you want. I hope we can find a suitable
compromise though.

Ian.