From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 20B1C5592 for ; Fri, 26 Feb 2016 15:49:14 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP; 26 Feb 2016 06:48:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,498,1449561600"; d="scan'208";a="921768322" Received: from bricha3-mobl3.ger.corp.intel.com ([10.237.208.63]) by orsmga002.jf.intel.com with SMTP; 26 Feb 2016 06:48:52 -0800 Received: by (sSMTP sendmail emulation); Fri, 26 Feb 2016 14:48:52 +0025 Date: Fri, 26 Feb 2016 14:48:52 +0000 From: Bruce Richardson To: "Wang, Xiao W" Message-ID: <20160226144852.GC21628@bricha3-MOBL3> References: <1454410216-13333-2-git-send-email-xiao.w.wang@intel.com> <20160225161406.GA22772@bricha3-MOBL3> <4126401.C51dJZWCEs@xps13> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH v3 1/3] fm10k: enable FTAG based forwarding X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Feb 2016 14:49:15 -0000 On Fri, Feb 26, 2016 at 09:24:06AM +0000, Wang, Xiao W wrote: > Hi, > > > -----Original Message----- > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > > Sent: Friday, February 26, 2016 5:06 PM > > To: Wang, Xiao W > > Cc: Richardson, Bruce ; Chen, Jing D > > ; dev@dpdk.org > > Subject: Re: [dpdk-dev] [PATCH v3 1/3] fm10k: enable FTAG based forwarding > > > > 2016-02-26 04:31, Wang, Xiao W: > > > From: Richardson, Bruce > > > > On Thu, Feb 25, 2016 at 03:45:45PM +0000, Chen, Jing D wrote: > > > > > From: Richardson, Bruce > > > > > > On Thu, Feb 25, 2016 at 10:04:02AM +0000, Chen, Jing D wrote: > > > > > > > This feature is trying to use FTAG (a unique tech in fm10k) > > > > > > > instead of mac/vlan to forward packets. App need a way to tell > > > > > > > PMD driver that which forwarding style it would like to use. > > > > > > > > > > > > Why not just specify this in the port configuration at setup time? > > > > > > > > > > > > > > > > Please educate me. I think the port configuration flags are also > > > > > common to all PMD Drivers. Is it possible to add a flag like > > "RTE_USE_FTAG" > > > > and pass to PMD driver? > > > > > > > > > They are. > > > > For something PMD specific, like FTAG, it's always a challenge, and > > > > I don't know off the top of my head if there is a simple option. > > > > However, given the choice between an mbuf flag and a port config > > > > flag, I'd always choose the former. > > > > Other alternatives would be to have a fm10k specific API in the > > > > fm10k driver alone. > > > > > > > > I'll let Thomas as ethdev maintainer comment if he has other > > > > suggestions as to how to handle this case. I suspect this won't be > > > > the first device-specific piece of functionality we need to deal with. > > > > > > > > /Bruce > > > > > > Whatever method we choose, we have to find a way for the user to > > > express his need for FTAG, it maybe a build time config option, or a > > > port config flag (no such flag now), or a fast path flag in mbuf (no > > > such flag now) etc. For the customer Topsec's use case, they use FTAG > > > for all the TX packets, so all the above methods (per build config, > > > per port config, per mbuf config) can meet their need. Since the pmd > > > frame work is for common, it's hard to add new fields only for one specific > > NIC, so I add a build time config and make an introduction in the doc. > > > > > > Thanks for the discussion, Thomas, do you have any suggestions? > > > > I don't understand why you say this feature is specific to fm10k. Can we > > imagine another NIC having this capability? > > As you know, fm10k has a switch logic between the Mac and Phy, every packets > Sent out from the host will be switched inside the NIC, other NICs don't have > a switch inside, and the FTAG feature is related to the switch function. > > As introduced in the second patch: > The FM10K family of NICs support the addition of a Fabric Tag (FTAG) to carry > special information. The FTAG is placed at the beginning of the frame, it contains > information such as where the packet comes from and goes, and the vlan tag. In > FTAG based forwarding mode, the switch logic forwards packets according to > glort (global resource tag) information, rather than the mac and vlan table. > So this is a feature specific to fm10k. > > Best Regards, > Xiao If it is fm10k specific, how about just adding a public function to the fm10k driver to turn it on. The user app will be non-portable across NICs, but that's the price of using nic-specific features. /Bruce > > I think it must be an port configuration, as Bruce suggested. > > What about a field in struct rte_eth_conf?