[Libvir] PATCH: strip auto-generated VIF names from XML

[Richard W.M. Jones]

Daniel P. Berrange wrote:
> For the QEMU / KVM driver, if the user doesn't specify an explicit name for
> the TAP device associated with a virtual NIC, we auto-generate one with a
> name vnetXXX.  You can see this if you dump XML for a running QEMU guest.
> Unfortunately if you dump XML, make a change and then feed it back in with
> the define XML API, you have now persisted this auto-generated VIF name.
> 
> Do this for several domains at varying times and you'll eventually  get
> 2 domains which have persisted the same auto-generated vnetXXX device
> name. You can now not start both of these VMs at once.
> 
> The fix for this is simple - simply strip any TAP device name starting with
> the string 'vnet' when defining a new VM. It will thus get assigned a new
> automatically generate name which doesn't clash. The patch also strips out
> hardcoded vnetXXX names when starting a VM to proactively deal with any
> existing VMs whose config has been broken in this way.

Hang about though, don't we sometimes want to explicitly set the name of 
some interfaces to vnetXXX?

Rich.

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