Re: [libvirt] [PATCH v1] libxl: reverse defaults on HVM net device attach

On 12/14/2016 03:53 AM, Joao Martins wrote: > libvirt libxl picks its own default with respect to the default NIC > to use. libxlMakeNic is the one responsible for this and on boot it > picks LIBXL_NIC_TYPE_VIF_IOEMU for HVM domains such that it accomodates > both PV and emulated one. The good behaving guest at boot will then > select the pv and unplug the emulated device. > > Now, on HVM when attaching an interface it will pick the same default > that is LIBXL_NIC_TYPE_VIF_IOEMU which as a result will fail the attach > (see xen commit 32e9d0f ("libxl: nic type defaults to vif in hotplug for > hvm guest"). Xen doesn't yet support the hotplug of emulated devices, > but we don't want to rule out that case either, which might get support > in the future. Hence we simply reverse the defaults when we are > attaching the interface which allows libvirt to prefer the PV nic first > without adding "model='netfront'" following the same pattern as above > commit. Also to avoid ruling out the emulated one we set to > LIBXL_NIC_TYPE_IOEMU when setting a model type that is not 'netfront'. > > Signed-off-by: Joao Martins <joao.m.martins(a)oracle.com&gt; > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > Since RFC: > - Joao: Add mention to HVM domains in the first paragraph of commit > message. > - Jim: Add comment about libxl_device_nic type inner workings > - Jim: Prevent attach on PV when model != netfront > - Joao: Remove now unused ioemu_nic variable > - Joao: Append one small paragraph about why we mimic xl/libxl > --- > src/libxl/libxl_conf.c | 39 +++++++++++++++++++++++++++++++-------- > src/libxl/libxl_conf.h | 3 ++- > src/libxl/libxl_driver.c | 2 +- > 3 files changed, 34 insertions(+), 10 deletions(-) ACK and pushed.