Re: [patch] xen udev rule interfering with openvpn

[Ian Campbell <Ian.Campbell@citrix.com>]

On Fri, 2012-04-20 at 11:38 +0100, Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [patch] xen udev rule interfering with openvpn"):
> > libxl/xend: name tap devices with a xentap prefix
> ...
> > Also add "xentap-" prefix to the tap device when an explicit name is
> > given to avoid a conflict with the vif device, which would otherwise
> > have the same name.  Likewise correct the documentation for this
> > option which suggested it applied to HVM tap devices only.
> 
> This sounds like a good idea but of course the names of interfaces
> on Linux have a fairly short (16 character) iirc length limit.

Oh, right, I'd forgotten that.

>   Are we
> sure that this isn't going to break some existing setup where the name
> is already using most of the available length ?

On the contrary I'm fairly sure it will break them... How common they
would be I can't say (other than my gut feeling being "not very").

Not sure what our options are here. Perhaps in the grant Unix tradition
of dropping vowels and random consonants "xtp-". Or perhaps "emu-" (for
emulated)?

This still adds a new 4 char prefix in the xl case but xend already had
that behaviour so hopefully people haven't come to rely on it in the
meantime.

Ian.