Hi,

I faced a couple of issues with libvirt update-device function:

1. http://libvirt.org/hvsupport.html says that virDomainUpdateDeviceFlags is supported since 0.8.0 API version in qemu driver.

However when trying to update network device (changing source bridge of the interface) on Ubuntu with 0.9.8 libvirt version I get the following error:

"this function is not supported by the connection driver: cannot modify network device configuration"

What may be the reason for such error?

2. Not able to rename target device name of an interface. For example if have running instance with interface:

<interface type='bridge'>

<mac address='fa:16:3e:80:f4:49'/>

<source bridge='qbre1894135-13'/>

<target dev='vnet0'/>

<model type='virtio'/>

<alias name='net0'/>

<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>

</interface>

and then try to update:

$ sudo virsh update-device --persistent --config --live 1 dev.xml

where dev.xml:

<interface type='bridge'>

<mac address='fa:16:3e:80:f4:49'/>

<source bridge='qbre1894135-13'/>

<target dev='tap123'/>

<model type='virtio'/>

</interface>

I get:

error: Failed to update device from dev.xml

error: Operation not supported: cannot modify network device tap name

This happens even if rename vnet0 to tap123 manually with ip link set vnet0 name tap123 before interface update.

And after instance reboot tap123 is renamed back to vnet0.

Is there a strong reason to not allow modifying network device tap name?

Will appreciate any assistance with the described issues.

Thanks,

Oleg