From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuanhan Liu Subject: Re: [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id Date: Fri, 23 Sep 2016 17:16:09 +0800 Message-ID: <20160923091609.GC23158@yliu-dev.sh.intel.com> References: <1473774463-26966-1-git-send-email-ciara.loftus@intel.com> <3895093.sl81aq1Okb@xps13> <20160923042641.GP23158@yliu-dev.sh.intel.com> <4215863.mCAoc6du0K@xps13> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ciara Loftus , dev@dpdk.org, "Wiles, Keith" To: Thomas Monjalon Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id A27B75A0A for ; Fri, 23 Sep 2016 11:15:41 +0200 (CEST) Content-Disposition: inline In-Reply-To: <4215863.mCAoc6du0K@xps13> 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" On Fri, Sep 23, 2016 at 10:43:20AM +0200, Thomas Monjalon wrote: > 2016-09-23 12:26, Yuanhan Liu: > > On Thu, Sep 22, 2016 at 06:43:55PM +0200, Thomas Monjalon wrote: > > > > > > > > > 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. > > > > > > > > It's not, instead, it's very generic. The "internal id" is actually the > > > > public interface to vhost-user application, like "fd" to file APIs. > > > > > > > > Instead of introducing a few specific wrappers/APIs, I'd prefer to > > > > introduce a generic one to get the handle, and let the application to > > > > call other vhost APIs. > > > > > > Yes it makes sense. > > > I was thinking of introducing a function to get an internal id from ethdev, > > > in order to use it with any driver or underlying library. > > > But it would be an opaque pointer and you need an int. > > > Note that we can cast an int into a pointer, so I am not sure what is best. > > > > Yes, that should work. But I just doubt what the "opaque pointer" could be > > for other PMD drivers, and what the application could do with it. For a > > typical nic PMD driver, I can think of nothing is valuable to export to > > user applications. > > > > But maybe it's valuable to other virtual PMD drives as well, like the TAP > > pmd from Keith? > > > > If so, we may go that way. > > I would like to have more opinions/votes before proceeding. Sure, fair enough. There is no rush. > > Another thought is that, it may be a bit weird to me to introduce an API > > to get an opaque pointer. I mean, it's a bit hard to document it, because > > it has different meaning for different drivers. Should we list all of > > them then? > > I think it can be documented in API using this handler how it can > be retrieved. In your case, the vhost lib can explain that the vid > is retrieved from the PMD with this generic ethdev function. Okay. --yliu