From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH] public/io/netif.h: change semantics of
 "request-multicast-control" flag
Date: Wed, 20 Jan 2016 13:06:17 +0000
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To: Paul Durrant <paul.durrant@citrix.com>, xen-devel@lists.xenproject.org
Cc: Keir Fraser <keir@xen.org>, Ian Jackson <ian.jackson@eu.citrix.com>, Jan Beulich <jbeulich@suse.com>, Tim Deegan <tim@xen.org>
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On Wed, 2016-01-20 at 12:50 +0000, Paul Durrant wrote:
> My patch b2700877 "move and amend multicast control documentation"
> clarified use of the multicast control protocol between frontend and
> backend. However, it transpires that the restrictions that documentation
> placed on the "request-multicast-control" flag make it hard for a
> frontend to enable 'all multicast' promiscuous mode, in that to do so
> would require the frontend and backend to disconnect and re-connect.

Do we therefore think that this document reflected reality, i.e. might this
not be "just" a documentation bug?

(Or maybe we can't tell because the only previous implementation was years
ago in Solaris or something)

> This patch adds a new "feature-dynamic-multicast-control" flag to allow
> a backend to advertise that it will watch "request-multicast-control" hence
> allowing it to be meaningfully modified by the frontend at any time rather
> than only when the frontend and backend are disconnected.

Would allowing XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL} to take a bcast address
be easier on the backend, in that it would just need to be a static feature
rather than watching stuff on the fly?