Re: PCI Device Subtree Change from Traditional to Upstream

From: Paul Durrant <Paul.Durrant@citrix.com>
To: Kevin Stange <kevin@steadfast.net>
Cc: Anthony Perard <anthony.perard@citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	George Dunlap <George.Dunlap@citrix.com>
Subject: Re: PCI Device Subtree Change from Traditional to Upstream
Date: Thu, 4 Jan 2018 13:26:04 +0000	[thread overview]
Message-ID: <017beab01afb490bba6c8c42040c341b@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <20180104125217.GB1905@perard.uk.xensource.com>

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On Behalf
> Of Anthony PERARD
> Sent: 04 January 2018 12:52
> To: Kevin Stange <kevin@steadfast.net>
> Cc: George Dunlap <George.Dunlap@citrix.com>; xen-
> devel@lists.xenproject.org
> Subject: Re: [Xen-devel] PCI Device Subtree Change from Traditional to
> Upstream
> 
> On Wed, Jan 03, 2018 at 05:10:54PM -0600, Kevin Stange wrote:
> > On 01/03/2018 11:57 AM, Anthony PERARD wrote:
> > > On Wed, Dec 20, 2017 at 11:40:03AM -0600, Kevin Stange wrote:
> > >> Hi,
> > >>
> > >> I've been working on transitioning a number of Windows guests under
> HVM
> > >> from using QEMU traditional to QEMU upstream as is recommended in
> the
> > >> documentation.  When I move these guests, the PCI subtree for Xen
> > >> devices changes and Windows creates a totally new copy of each
> device.
> > >> Windows tracks down the storage without issue, but it treats the new
> > >> instance of the NIC driver as a new device and clears the network
> > >> configuration even though the MAC address is unchanged.  Manually
> > >> booting the guest back on the traditional device model reactivates the
> > >> original PCI subtree and the old network configuration with it.
> > >>
> > >> The only thing that I have been able to find that's substantially
> > >> different comparing the device trees is that the device instance ID
> > >> values differ on the parent Xen PCI device:
> > >>
> > >>
> PCI\VEN_5853&DEV_0001&SUBSYS_00015853&REV_01\3&267A616A&3&18
> > >>
> > >>
> PCI\VEN_5853&DEV_0001&SUBSYS_00015853&REV_01\3&267A616A&3&10
> > >>
> > >> Besides actually setting the guest to boot using QEMU traditional, is
> > >> there a way to convince Windows to treat these devices as the same?  A
> > >> patch-based solution would be acceptable to me if there is one, but I
> > >> don't understand the code well enough to create my own solution.

Kevin,

I missed the original email as it went past...

Are Xen Project PV drivers installed in the guest? And are you talking about a PV NIC device or an emulated device?

  Paul
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