Re: [Bridge] [RFC v2 1/4] bridge: enable interfaces to opt out from becoming the root bridge

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 14 Feb 2014 18:59:37 -0800
"Luis R. Rodriguez" <mcgrof@do-not-panic.com> wrote:

> From: "Luis R. Rodriguez" <mcgrof@suse.com>
> 
> It doesn't make sense for some interfaces to become a root bridge
> at any point in time. One example is virtual backend interfaces
> which rely on other entities on the bridge for actual physical
> connectivity. They only provide virtual access.
> 
> Device drivers that know they should never become part of the
> root bridge have been using a trick of setting their MAC address
> to a high broadcast MAC address such as FE:FF:FF:FF:FF:FF. Instead
> of using these hacks lets the interfaces annotate its intent and
> generalizes a solution for multiple drivers, while letting the
> drivers use a random MAC address or one prefixed with a proper OUI.
> This sort of hack is used by both qemu and xen for their backend
> interfaces.
> 
> Cc: Stephen Hemminger <stephen@networkplumber.org>
> Cc: bridge@lists.linux-foundation.org
> Cc: netdev@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>

This is already supported in a more standard way via the root
block flag.