This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


[Xen-devel] PATCH: Don't clobber VIF 'type' field when starting a HVM gu

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] PATCH: Don't clobber VIF 'type' field when starting a HVM guest
From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Date: Thu, 27 Sep 2007 17:28:59 +0100
Delivery-date: Thu, 27 Sep 2007 09:29:41 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Reply-to: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.4.1i
In the Xen 3.1.0 series releases the 'VIF' config has a 'type' field which is
used to determine if using QEMU's emulated NIC vs netfront/back.

 - type=ioemu  -> Setup QEMU with an rtl8139 nic
 - type=netfront -> Setup netback, assuming HVM pv drivers
 - type is None  -> Setup QEMU with rtl8139 nic & netback

In Fedora (and libvirt) we default to leaving 'type' as None, so that users
do not have to change the Dom0 guest config simply to install PV drivers in
an HVM guest.

There is one unfortunate bug though - when you start a managed VM, XenD will
re-save its configuration out to disk under /var/lib/xend/domains/[UUID]
and in doing so, it converts type=None into type=netfront. This isn't an
immediate problem because the config in memory is never changed & still
has correct settings. But some days/months later when the machine is rebooted
or XenD is restarted, it reads the config from disk & thus the rtl8139 nic
disappears from all your HVM guests :-(

The attached patch fixes server/netif.py so that it respects type=None as
the rest of the XenD code does. The patch is against xen-3.1-testing.hg
but also needs to be applied to xen-unstable.hg

  Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx>

|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=| 

Attachment: xen-vif-type-clobber.patch
Description: Text document

Xen-devel mailing list
<Prev in Thread] Current Thread [Next in Thread>
  • [Xen-devel] PATCH: Don't clobber VIF 'type' field when starting a HVM guest, Daniel P. Berrange <=