From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id Date: Wed, 21 Sep 2016 15:07:51 +0200 Message-ID: <1673736.mOMazzh4h1@xps13> References: <1473774463-26966-1-git-send-email-ciara.loftus@intel.com> <2149205.E6pxXR7o4C@xps13> <20160918082718.GF23158@yliu-dev.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Ciara Loftus , dev@dpdk.org To: Yuanhan Liu Return-path: Received: from mail-wm0-f43.google.com (mail-wm0-f43.google.com [74.125.82.43]) by dpdk.org (Postfix) with ESMTP id 380BB2B9E for ; Wed, 21 Sep 2016 15:07:54 +0200 (CEST) Received: by mail-wm0-f43.google.com with SMTP id b130so91015259wmc.0 for ; Wed, 21 Sep 2016 06:07:54 -0700 (PDT) In-Reply-To: <20160918082718.GF23158@yliu-dev.sh.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 2016-09-18 16:27, Yuanhan Liu: > On Wed, Sep 14, 2016 at 10:35:53AM +0200, Thomas Monjalon wrote: > > 2016-09-14 15:21, Yuanhan Liu: > > > On Wed, Sep 14, 2016 at 09:10:48AM +0200, Thomas Monjalon wrote: > > > > 2016-09-14 12:43, Yuanhan Liu: > > > > > On Tue, Sep 13, 2016 at 05:10:09PM +0200, Thomas Monjalon wrote: > > > > > > 2016-09-13 14:47, Ciara Loftus: > > > > > > > In some cases when using the vHost PMD, certain vHost library functions > > > > > > > may still need to be accessed. One such example is the > > > > > > > rte_vhost_get_queue_num function which returns the number of virtqueues > > > > > > > reported by the guest - information which is not exposed by the PMD. > > > > > > > > > > > > > > This commit introduces a new rte_eth_vhost function that returns the > > > > > > > 'vid' associated with a given port id. This allows the PMD user to call > > > > > > > vHost library functions which require the 'vid' value. > > > > > > > > > > > > I think we should not add any API to the PMDs. > > > > > > > > > > In general, I agree with you. > > > > > > > > > > > Maybe you are looking for a generic API in ethdev. > > > > > > > > > > But maybe it's a bit hard to define a "right" generic API here. For this > > > > > case, the generic API I can think of could be: > > > > > > > > > > - an API to get queue num, like rte_eth_get_queue_enabled_num > > > > > I barely know NIC pmd drivers, but I doubt it's useful/meaningful for them. > > > > > > > > > > - an API to get a PMD driver private (or specific) data. > > > > > For vhost-pmd, it's vid. Again, I don't know what it could be for other nic > > > > > drivers. > > > > > > > > > > This one may be a better option here, because it expose a key field to > > > > > the application, vid, with which the application can invoke more vhost > > > > > APIs. And apparently, it's not feasible to try to define a generic API > > > > > for some (if not each) vhost APIs. > > > > > > > > There could be a similar need in other PMD. > > > > If we can get an opaque identifier of the device which is not the port id, > > > > we could call some specific functions of the driver not implemented in > > > > the generic ethdev API. > > > > > > That means you have to add/export the PMD API first. Isn't it against what > > > you are proposing -- "I think we should not add any API to the PMDs" ;) > > > > Yes you are totally right :) > > Except that in vhost case, we would not have any API in the PMD. > > But it would allow to have some specific API in other PMDs for the features > > which do not fit in a generic API. > > So, does that mean you are okay with this patch now? I mean, okay to introduce > a vhost PMD API? It means I would be in favor of introducing API in drivers for very specific features. In this case, I am not sure that retrieving an internal id is very specific. Opinions are welcome