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

From: Stephen Hemminger
Date: Sun Feb 16 2014 - 13:58:06 EST


On Fri, 14 Feb 2014 18:59:37 -0800
"Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx> wrote:

> From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
>
> 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@xxxxxxxxxxxxxxxxxx>
> Cc: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: netdev@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>

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

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