From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH v2] net/enic: add private API to set ingress VLAN rewrite mode Date: Wed, 13 Mar 2019 22:29:53 +0100 Message-ID: <119440374.MxkLxCl2uq@xps> References: <20190305055659.3095-1-hyonkim@cisco.com> <155267265.tCld3OmuaL@xps> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Ferruh Yigit , "Hyong Youb Kim (hyonkim)" , Andrew Rybchenko , Qi Zhang , "dev@dpdk.org" , Shahaf Shuler , Jerin Jacob , David Marchand , Maxime Coquelin , Konstantin Ananyev , Hemant Agrawal , Stephen Hemminger To: "John Daley (johndale)" Return-path: Received: from out2-smtp.messagingengine.com (out2-smtp.messagingengine.com [66.111.4.26]) by dpdk.org (Postfix) with ESMTP id 610D62BD3 for ; Wed, 13 Mar 2019 22:29:58 +0100 (CET) In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 13/03/2019 22:11, John Daley (johndale): > From: Thomas Monjalon > > 13/03/2019 19:32, Ferruh Yigit: > > > On 3/5/2019 7:11 AM, Hyong Youb Kim wrote: > > > > The driver currently has a devarg to set the rewrite mode during > > > > init. Some apps want to programatically set it after running > > > > rte_eal_init() and finding that ports are VIC. Add a private > > > > function to support such applications. > > > > > > It is not good idea to have PMD specific APIs (although we already have > > some). > > > > > > Specific to this case, as far as I can see it is to pass a config > > > value and do the action related to it, what would you think having a > > > generic key/value set/get API in ethdev for this? Similar to rawdev > > get_attr/set_attr [1]? > > > > > > My concern is it may turn into something like ioctl with many things > > > pushed to it, and cause possible duplication ... > > > > Yes, it is clearly ioctl style. > > > > Please could you explain more what is the rewrite mode? > > Does it apply to the port or the queue? > > > It applies to a port. By default the Cisco VIC VLAN tags every packet on ingress even if they were untagged coming in on the wire. They are tagged with VLAN 0 or a VLAN id programmed into the NIC depending on the configuration. Its part of the original design, to maintain priority bits, ancient history. > > Some apps don't like this (VPP) or take a slower path (OVS). Hyong added a ig-vlan-rewrite=untag devarg to disable this (leave untagged/default vlan packets untagged) during rte_eal_init and this is helpful for OVS, but VPP likes to set the rewrite mode after rte_eal_init() and finding the ports are VIC ports. So that is the reasoning behind the private API call. It looks like an application will always set this flag or never. So I don't see the need for an API function. Why VPP prefers set this flag later? Would it be better to have some driver-specific flags, no matter the ports?