libvirt users - Jul 2014 - virsh update-device issues

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

On Tue, Jul 01, 2014 at 06:06:01PM +0400, Oleg Bondarev
wrote:
>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?
>
To be honest, I don't know how exactly this works, but does it work if
you try updating it without --live?  Probably nobody added the support
for changing the device name live; that would be my guess.

Martin
>Will appreciate any assistance with  the described issues.
>
>Thanks,
>Oleg
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