Re: vif-bridge: ip link set failed, "name" too long

[Jim Fehlig <jfehlig@suse.com>]

On 06/25/2015 05:53 AM, Ian Campbell wrote:
> On Thu, 2015-06-25 at 12:36 +0100, Anthony PERARD wrote:
>> Error: argument "tap695cf459-b0-emu" is wrong: "name" too long
> Under Linux IFNAMSIZ is 16, whereas this is 18 characters.
>
> Since our suffix is "-emu" we are adding 4 to the original 14, so we
> could/should pick a 2 character suffix to distinguish PV from emulated
> interfaces. "-e" perhaps?

I'm not familiar with Neutron, but might this break some rules or filters it 
creates based on the name? Appending stuff to a user-provided name doesn't seem 
right.

One way to avoid the emulated interface is to set libxl_device_nic->nictype = 
LIBXL_NIC_TYPE_VIF, so only the pv interface is created. In xl.cfg, I suppose 
that would be

   vif = [ '...,model=netfront' ]

In libvirt domXML

   <interface>
     ...
     <model type='netfront'/>
   </interface>

I realize that doesn't help much if the guest has no pv network driver. I wonder 
how this is handled in KVM? In the libvirt qemu driver, the default interface 
model is rtl8139 if <model type=''/> is not specified.  Does nova add <model 
type='virtio'/> to interfaces for KVM instances? Is it expected that the guest 
OS has a virtio network driver?

Regards,
Jim