On 3/31/21 1:36 PM, Daniel P. Berrangé wrote:
On Wed, Mar 31, 2021 at 01:09:32PM +0200, Michal Privoznik wrote:
On 3/30/21 11:35 AM, Waleed Musa wrote:
Hi all,
I see in libvirt you are supporting attach/detach devices to existing
xml domain using *attachDeviceFlags *and *detachDeviceFlags *APIs.
Now we are adding some qemu command to the xml domain related to some
interfaces using alias names before starting the VM, but we will face an
issue with hot plug such devices, so I have two question here:
1. Is it applicable to set the alias names for interfaces because I saw
it's ignored when I add it to xml domain before starting the VM?
2. Is there a way or API to attach qemu commands to running domain as
you are doing in attaching the device using *attachDeviceFlags?*
*Example of my xml*
*<domain type='kvm' id='5'
xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
*
* <devices>
*
<interface type='vhostuser'>
<mac address='fa:16:3e:ac:12:4c'/>
<source type='unix'
path='/var/lib/vhost_sockets/sockbbb6bbe9-eb5' mode='server'/>
<target dev='tapbbb6bbe9-eb'/>
<model type='virtio'/>
<driver queues='4' rx_queue_size='512' tx_queue_size='512'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
* </devices>
*
* <qemu:commandline>*
<qemu:arg value='-set'/>
<qemu:arg value='device.net0.page-per-vq=on'/>
<qemu:arg value='-set'/>
<qemu:arg value='device.net0.host_mtu=8942'/>
* </qemu:commandline>*
*</domain>*
Is this perhaps related to the following bug?
"interface type='vhostuser' libvirtError: Cannot set interface MTU"
https://bugzilla.redhat.com/show_bug.cgi?id=1940559
Are you trying to work around it? I am discussing with Moshe how libvirt can
help, but honestly, I don't like the solution I proposed.
Long story short, the interface is in different container (among with OVS
bridge) and thus when we query ovs-vsctl it connects to the system one and
doesn't find that interface. What I proposed was to allow specifying path to
ovs db.socket but this would need to be done o per domain basis.
If it is possible to specify a ovs db.socket path in the XML, then
why can't this path simply be bind mounted to the right location
in the first place.
Because then you'd override the path for system wide OVS. I mean, by
default the socket is under /var/run/openvswitch/db.sock and if you have
another OVS running inside a container you can expose it under
/prefix/var/run/openvswitch/db.sock. ovs-vsctl allows this by --db=$path
argument.
Michal
