Re: [Qemu-devel] [Xen-devel] [PATCH] Add Xen platform PCI device version 2.

[Tim Deegan <tim@xen.org>]

At 11:07 +0100 on 19 Jun (1371640052), Ian Campbell wrote:
> On Wed, 2013-06-19 at 10:43 +0100, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Ian Campbell
> > > Sent: 19 June 2013 10:42
> > > To: Paul Durrant
> > > Cc: qemu-devel@nongnu.org; xen-devel@lists.xen.org
> > > Subject: Re: [Xen-devel] [PATCH] Add Xen platform PCI device version 2.
> > > 
> > > On Wed, 2013-06-19 at 10:32 +0100, Paul Durrant wrote:
> > > > The XenServer 6.1+ Citrix Windows PV bus driver binds to a new version
> > > > of the Xen platform device (since the newer driver set cannot co-exist
> > > > with previous drivers which bind to the existing "xen-platform" type of
> > > > device). This patch introduces a new "xen-platform-2" device type with
> > > > the appropriate device_id and revision.
> 
> We obviously can't say to users "Are you running Windows and are you
> running PV drivers >= X.Y, if so set lever A to position B, otherwise if
> you are running some other OS or an earlier version of the Windows PV
> driver set it to position A".

Agreed - that's a horrible interface, and an egregious layer violation.
The VM's admin should be able to install/upgrade software without
involving the host admin.

Can you explain a bit more about why this is needed?  Presumably 'real'
device manufacturers can ship new versions of their drivers through
Windows Update without needing to rev their hardware or get the user to
change BIOS settings.

Tim.