From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH v3 1/2] ethdev: add capability control API Date: Mon, 06 Mar 2017 17:57:15 +0100 Message-ID: <12629083.yAQ7FffjSn@xps13> References: <1488589820-206947-1-git-send-email-cristian.dumitrescu@intel.com> <2480022.hlQWxlV5d8@xps13> <3EB4FA525960D640B5BDFFD6A3D8912652759FC7@IRSMSX108.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev@dpdk.org, "jerin.jacob@caviumnetworks.com" , "balasubramanian.manoharan@cavium.com" , "hemant.agrawal@nxp.com" , "shreyansh.jain@nxp.com" , "Wiles, Keith" , "Richardson, Bruce" To: "Dumitrescu, Cristian" Return-path: Received: from mail-wr0-f173.google.com (mail-wr0-f173.google.com [209.85.128.173]) by dpdk.org (Postfix) with ESMTP id 609F66CD4 for ; Mon, 6 Mar 2017 17:57:17 +0100 (CET) Received: by mail-wr0-f173.google.com with SMTP id u108so121066697wrb.3 for ; Mon, 06 Mar 2017 08:57:17 -0800 (PST) In-Reply-To: <3EB4FA525960D640B5BDFFD6A3D8912652759FC7@IRSMSX108.ger.corp.intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 2017-03-06 16:35, Dumitrescu, Cristian: > Hi Thomas, > > Thanks for reviewing this proposal. > > > > > Signed-off-by: Cristian Dumitrescu > > > Acked-by: Keith Wiles > > > Acked-by: Jerin Jacob > > > Acked-by: Hemant Agrawal > > [...] > > > +enum rte_eth_capability { > > > + RTE_ETH_CAPABILITY_FLOW = 0, /**< Flow */ > > > + RTE_ETH_CAPABILITY_TM, /**< Traffic Manager */ > > > + RTE_ETH_CAPABILITY_MAX > > > +}; > > [...] > > > /** > > > + * Take capability operations on an Ethernet device. > > > + * > > > + * @param port_id > > > + * The port identifier of the Ethernet device. > > > + * @param cap > > > + * The capability of the Ethernet device > > > + * @param arg > > > + * A pointer to arguments defined specifically for the operation. > > > + * @return > > > + * - (0) if successful. > > > + * - (-ENOTSUP) if hardware doesn't support. > > > + * - (-ENODEV) if *port_id* invalid. > > > + */ > > > +int rte_eth_dev_capability_ops_get(uint8_t port_id, > > > + enum rte_eth_capability cap, void *arg); > > > > What is the benefit of getting different kind of capabilities with > > the same function? > > enum + void* = ioctl > > A self-explanatory API should have a dedicated function for each kind > > of features with different argument types. > > The advantage is providing a standard interface to query the capabilities of the device rather than having each capability provide its own mechanism in a slightly different way. > > IMO this mechanism is of great help to guide the developers of future ethdev features on the clean path to add new features in a modular way, extending the ethdev functionality while doing so in a separate name space and file (that's why I tend to call this a plugin-like mechanism), as opposed to the current monolithic approach for ethdev, where we have 100+ API functions in a single name space and that are split into functional groups just by blank lines in the header file. It is simply the generalization of the mechanism introduced by rte_flow in release 17.02 (so all the credit should go to Adrien and not me). > > IMO, having a standard function as above it cleaner than having a separate and slightly different function per feature. People can quickly see the set of standard ethdev capabilities and which ones are supported by a specific device. Between A) and B) below, I definitely prefer A): > A) status = rte_eth_dev_capability_ops_get(port_id, RTE_ETH_CABABILITY_TM, &tm_ops); > B) status = rte_eth_dev_tm_ops_get(port_id, &tm_ops); I prefer B because instead of tm_ops, you can use some specific tm arguments, show their types and properly document each parameter.