From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [libvirt] Setting devid for emulated NICs (Xen
 4.3.1 / libvirt 1.2.0) using libxl driver
Date: Fri, 20 Dec 2013 10:11:02 +0000
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To: Jim Fehlig <jfehlig@suse.com>
Cc: libvir-list@redhat.com, Stefan Bader <stefan.bader@canonical.com>, Xen-devel@lists.xen.org
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On Thu, 2013-12-19 at 11:39 -0700, Jim Fehlig wrote:
> Stefan Bader wrote:
> > Oh, just while talking about setdefault. Jim, this is one of the odd things when
> > moving from xm to xl stack from libvirt: libvirt defaults to the netfront NIC
> > when no model is specified and sets the type. The libxl setdefault function sets
> > the model to rtl8139 but leaves the type untouched.
> 
> The xend toolstack always creates both emulated and vif devices unless
> 'type=netfront' is explicitly specified.  As you say, the guest gets to
> choose what to do with them.  E.g. PXE boot using the emulated device,
> or have the driver for the PV device unplug the emulated one.  I don't
> think libxl supports this right?

It should do, in fact I thought it was the default.

How are you initialising the libxl_device_nic? Type ==  VIF_IOEMU (which
is the default for a VIF on an HVM guest) means both emulated and pv.
(there were bugs in the semantics here in very early versions of libxl,
but I thought they were fixed even before 4.2)

I don't think there is an option to have just the emulated device --
there is always a PV VIF there even if the guest doesn't use it.

Ian.