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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id x3sm275715qts.35.2020.02.19.08.58.00 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 19 Feb 2020 08:58:00 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1j4Sfg-0005CW-6K; Wed, 19 Feb 2020 12:58:00 -0400 Date: Wed, 19 Feb 2020 12:58:00 -0400 From: Jason Gunthorpe To: Dennis Dalessandro Cc: Leon Romanovsky , "linux-rdma@vger.kernel.org" , Honggang LI , Gal Pressman Subject: Re: RDMA device renames and node description Message-ID: <20200219165800.GS31668@ziepe.ca> References: <5ae69feb-5543-b203-2f1b-df5fe3bdab2b@intel.com> <20200218140444.GB8816@unreal> <1fcc873b-3f67-2325-99cc-21d90edd2058@intel.com> <20200219071129.GD15239@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Feb 19, 2020 at 09:14:06AM -0500, Dennis Dalessandro wrote: > > ABI breakage is a strong word, luckily enough it is not defined at all. > > We never considered dmesg prints, device names, device ordering as an > > ABI. You can't rely on debug features too, they can disappear too. > > Agree, it is a strong word and we can call it what you want. The point is > you should be able to rely on the node description not being changed out > from under you unnecessarily though. We aren't talking about a debug feature > here but a core feature to real world deployments. People really use the node description as some stable name? And then they put the HCA name in it? Why? Is that some thing unique to the OPA subnet manager? I don't recall people complaining about this when we introduced rdma-ndd by default and changed all the node descriptions away from the kernel default. Also don't forget the whole thing about the node description is inherently racey, so relying on it is Rather A Bad Idea. Should we change the default format string of rdma-ndd to something else? Jason