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Date: Mon, 1 Apr 2013 02:12:51 +0200
From: Samuel Thibault <samuel.thibault@labri.fr>
Message-ID: <20130401001251.GD17794@type.youpi.perso.aquilenet.fr>
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Subject: [Qemu-devel] [PATCH] Document mcast+ipv6 (Was: Re: socket,
 mcast looping back frames -> IPv6 broken)
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: ped@listes.subiron.org, qemu-devel@nongnu.org

Stefan Hajnoczi, le Mon 11 Mar 2013 09:36:14 +0100, a =E9crit :
> > Otherwise we may just document that one has to disable Duplicate Addr=
ess
> > Detection to get IPv6 working :/
>=20
> Seems like this might be the only way for now.

Here is a patch

Samuel


Document how to get IPv6 working with mcast socket

Document that IPv6 can not work in mcast mode unless disabling DAD in
the guest.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

diff --git a/qemu-options.hx b/qemu-options.hx
index c40ba55..9074a24 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1683,6 +1683,12 @@ mcast support is compatible with User Mode Linux (=
argument @option{eth@var{N}=3Dmc
 @url{http://user-mode-linux.sf.net}.
 @item
 Use @option{fd=3Dh} to specify an already opened UDP multicast socket.
+@item
+Since with multicast diffusion the guest will receive its own frames, it=
s IPv6
+Duplicate Address Detection (DAD) will erroneously detect a duplicate, t=
hus
+preventing IPv6 from working.  One has to disable DAD to get IPv6 workin=
g, for
+instance on Linux by setting the sysctl @code{net.ipv6.conf.all.accept_d=
ad} to
+0.
 @end enumerate
=20
 Example: