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[62.23.145.78]) by smtp.gmail.com with ESMTPSA id t14sm17505385wrs.6.2019.10.01.07.09.50 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 01 Oct 2019 07:09:50 -0700 (PDT) Date: Tue, 1 Oct 2019 16:09:48 +0200 From: =?iso-8859-1?Q?Ga=EBtan?= Rivet To: Jerin Jacob Cc: Stephen Hemminger , dpdk-dev , Slava Ovsiienko , Ferruh Yigit , Anatoly Burakov , Thomas Monjalon , Jerin Jacob Kollanukkaran , David Marchand Message-ID: <20191001140948.r35w2tpvx3fg6xiw@bidouze.vm.6wind.com> References: <30b29c553a1ae4faafbd2018ec3a6701b71d266a.1569846991.git.gaetan.rivet@6wind.com> <20190930115333.5302e457@hermes.lan> <20191001091013.xxtzjblepbleqren@bidouze.vm.6wind.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-dev] [PATCH v1] eal: add manual probing option X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Tue, Oct 01, 2019 at 03:19:42PM +0530, Jerin Jacob wrote: > On Tue, Oct 1, 2019 at 2:40 PM Gaëtan Rivet wrote: > > > > On Mon, Sep 30, 2019 at 11:53:33AM -0700, Stephen Hemminger wrote: > > > On Mon, 30 Sep 2019 14:51:03 +0200 > > > Gaetan Rivet wrote: > > > > > > > Add a new EAL option enabling manual probing in the EAL. > > > > This command line option will configure the EAL so that buses > > > > will not trigger their probe step on their own. > > > > > > > > Applications are then expected to hotplug devices as they see fit. > > > > > > > > Devices declared on the command line by the user (using -w and --vdev), > > > > will be probed using the hotplug API, in the order they are declared. > > > > > > > > This has the effect of offering a way for users to control probe order > > > > of their devices, for drivers requiring it. > > > > > > > > Signed-off-by: Gaetan Rivet > > > > > > I have no problems with the patch, but it would help if there was better > > > way to handle device naming policy in DPDK. Applications that depend on > > > particular port number are prone to get broken by changes in surrounding > > > OS or hardware environment. Just like Linux applications that are built > > > to depend on "eth0"; which is unfortunately all too common. > > > > Hello Stephen, > > > > This patch is a way to avoid having the PCI bus defining the probe order > > with the current hardware environment. It seems to be a step in the > > right direction for the issue you identify. > > > > There is a tight coupling between device names and driver matches for > > the vdev bus, but that seems difficult to avoid. > > > > Do you see other EAL APIs fostering an over reliance of downstream > > systems on device names? > > > > I pushed a few months back a way to iterate / match devices by their > > properties. If you identify other pain points, this could certainly be > > improved as well. > > > And this mode will be kicked in only when "--manual-probe" selected on > eal arguments. > So it won't change the behavior of the existing applications. If I read you correctly, if hardware independence is the proper way to function, we should switch entirely to it. I agree, but that means rewriting entirely the probe step of rte_bus. This patch is a incremental step, I preferred to keep risks low. It is not clear from your remark whether you are considering this limitation a good or a bad thing however :) Can you be a bit more explicit? -- Gaëtan Rivet 6WIND