From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Wise Subject: Re: bug 1918 - openmpi broken due to rdma-cm changes Date: Fri, 05 Feb 2010 10:45:08 -0600 Message-ID: <4B6C4B14.9000202@opengridcomputing.com> References: <58D723FE08DC6A4398E6596E38F3FA170566DA@XMB-RCD-205.cisco.com> <4B6C4460.3050908@opengridcomputing.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B6C4460.3050908-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Jeff Squyres (jsquyres)" Cc: sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ewg-G2znmakfqn7U1rindQTSdQ@public.gmane.org, "Roland Dreier (rdreier)" List-Id: linux-rdma@vger.kernel.org > I agree that we should probably not allow 127.0.0.1 binds in > ofed-1.5.1 at all because it regresses OpenMPI. Even with IB systems, > if the bind to 127.0.0.1 succeeds, then OpenMPI assumes 127.0.0.1 is > bound to that rdma interface and advertises this address to its peer > as an address to-which that peer can rdma connect! This will break IB > clusters too, not just T3/iWARP cluster. While I think OpenMPI needs > to skip 127.0.0.1 in its logic, I think we should probably defer > allowing 127.0.0.1 binds until ofed-1.6. > > But Jeff, note that if someone uses the upstream kernel and OpenMPI, > its busted... > > So I recommend: > > 1) Don't allow 127.0.0.1 binds in ofed-1.5.1 > > 2) Fix OpenMPI ASAP to never advertise 127.0.0.1 as a valid rdma-cm > connect address (get it in ofed-1.5.2 or ofed-1.6). Also, there is a good argument for never allowing 127.0.0.1 for rdma anyway. It implies a _software_ loopback. It should NEVER be bound to a real NIC interface and thus rdma binds shouldn't be allowed to it since there is no software rdma loopback support... Unless someone implements software rdma loobpack... ;) -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html