From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: Mellanox target workaround in SRP Date: Wed, 12 Jan 2011 15:40:58 +0200 Message-ID: <20110112134058.GA31084@redhat.com> References: <1294439717.6219.54.camel@lap75545.ornl.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roland Dreier Cc: David Dillow , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ewg-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org, ishai-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org List-Id: linux-rdma@vger.kernel.org On Mon, Jan 10, 2011 at 10:51:13AM -0800, Roland Dreier wrote: > Maybe we can use MST's current email to ask him... Michael, do you have > any memory of the issue we worked around here? > > > I have question regarding workaround introduced in commit 559ce8f1 of > > the mainline tree: > > > > IB/srp: Work around data corruption bug on Mellanox targets > > > > Data corruption has been seen with Mellanox SRP targets when FMRs > > create a memory region with I/O virtual address != 0. Add a > > workaround that disables FMR merging for Mellanox targets (OUI 0002c9). > > > > I don't see how this can make a difference to the target -- it sees an > > address and length, and there should be no visible difference to it when > > it gets an FMR versus a direct-mapped region of the same space, right? > > And how is it different than getting a direct or indirect descriptor > > with a similar offset? > > > > I could see there being a bug on the initiator HCA not liking such FMR > > mappings, but then it should be keyed off of the vendor of our HCA and > > not the target. > > > > I'm sure this was tested and shown to fix the problem; I'm just confused > > as to what the problem really was and if this is still relevant. Can > > someone please enlighten me? I don't recall unfortunately. Sorry. -- MST -- 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