[libvirt-users] question about libvirt network Xml

Robert Li (baoli) baoli at cisco.com
Fri Oct 24 14:16:31 UTC 2014

Hi Michal,

Thanks for the response. With openstack, neutron plugins need to know the
device identification (in this case, the device¹s vendor id , product id,
and slot information) in order to program the device, or probably the
upstream switch in the case of 802.1qbr. I know that libvirt programs the
sr-iov nic adaptor under the cover, but it doesn¹t seem to be able to
cover all. So in the case of network XML, nova/neutron won¹t be able to do
anything with the device since its id can¹t be obtained from libvirt.


On 10/24/14, 12:39 AM, "Michal Privoznik" <mprivozn at redhat.com> wrote:

>On 16.10.2014 19:29, Robert Li (baoli) wrote:
>> Hi,
>> I¹m an openstack developer trying to use
>>       Assignment from a pool of SRIOV VFs in a libvirt <network>
>> from this link http://wiki.libvirt.org/page/Networking
>> My question is is it possible for nova (the openstack compute) to know
>> which VF out of the pool will be allocated to a VM before it invokes
>> libvirt to launch it?
>In general no. Even though currently libvirt chooses the first free VF,
>this is not a part of API, and thus it's not written into a stone. I
>wouldn't rely on it. But the fact, you need this kind of information
>makes me wonder why. What's your use case?

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