Re: Specifying names for tap interfaces

[Roger Pau Monne <roger.pau%citrix.com@localhost>]

Martin Husemann wrote:
> On Thu, Jun 21, 2012 at 11:01:49AM +0100, Roger Pau Monne wrote:
> > While this is true if you give a name to the interface on the config
> > file, but how can the toolstack (xl, that launches Qemu) choose an
> > interface name and pass it to Qemu when no one is specified?
>
> Well, I would call that admin error and do:
>
>    if (name is specified)
>       try to create and use that
>    if (that fails || none was specified)
>       open the cloning /dev/tap and query the interface name

Then we end up with the same problem, since xl needs to know the name of 
the created device (to launch the appropriate hotplug scripts), and 
there's not way to fetch that from Qemu.

> (where "that fails" obviously includes name collisions with existing
> tap instances). This could give you an option usefull for NetBSD 6.0.
>
> Note that I am not objecting to fix the more general problem of
> creating aliases or rename support. However, of everything I saw
> discussed so far, only the FreeBSD variant has (a) clearly defined
> semantics and (b) is very simple to implement. It is so simple, it wouldn't
> hurt as a stopgap/intermediate solution.

I'm not completely sure the FreeBSD solution is easier to implement than 
the alias one, but at this point this shouldn't be our primary concern.

> Everything else, at least from my understanding, needs *a lot* more thought
> and design work - which does not mean it is the wrong way to go in the long
> term.
>
> Martin