From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f51.google.com (mail-wm0-f51.google.com [74.125.82.51]) by dpdk.org (Postfix) with ESMTP id 73D88377C for ; Mon, 26 Sep 2016 18:55:45 +0200 (CEST) Received: by mail-wm0-f51.google.com with SMTP id b130so159109090wmc.0 for ; Mon, 26 Sep 2016 09:55:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:user-agent:in-reply-to :references:mime-version:content-transfer-encoding; bh=7R8s9/SYEEDXt1LuPJLCWAupJO3vd9DP6+UWA/9aXjo=; b=U8JjGtifBeQvcRio63d/FwxAc+K37rvVukPwCKUXznukFfHFZqEY9AdSuTRzQwbnl7 fZ4kr2OTlJ6th0cgiBoIdKaG72RZ/THOAg3VW4BonbkgnE4kW0kwdYt9Du+eU5us2SFk 97nW2wZESRmmH0Fo7Bq6Jw3uT7rDDsEIEA6RLC6PIC4K16wuXL3TembNAiykaLIvSYgm 6kPtMFz4thSZnH3OC0gOpOZ4Ve26Hy7Ami+3y+rTZIBfIKCjnShGRFDcW/P4HqFmJOs6 mjfK+7RnAVJel4Ex++YkcPv618nU6tFupR79DZPnxquiQZMo88CSnCV99hfDPhV/yoDe qRHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-transfer-encoding; bh=7R8s9/SYEEDXt1LuPJLCWAupJO3vd9DP6+UWA/9aXjo=; b=c8AOpXujOKfJCHQh26VtDtCmykEhiEaBuBr8r+0OrUHk5RVR1FDpfT2C9wOkrS1366 tjFNy4/XttR1TOgaBaDOw7VF8C4qJZCCP3IIiUlV4Kb5sigfNUY8ySRIjzhr0A0PHah7 FAWwv5Tb9+OgPdzUwmaxlnP30AZcKuJFq7uWfPMKxOlBP65duBKBkQVHQ2fAqkC+Fi1a 27T/uig/22k+eh480zxN+voNo6ffVrHKUup/PTJuykAwwo1Gy0D2N5GWUsKu7aodswtG bT+DqbgTYe/MuNeDW1F86klReOwv8yzjPwOvZtTUSLuB31rTT6BZ7jSIMwU0Q8DIHhx1 ggSg== X-Gm-Message-State: AA6/9RkdxzDO19VeJkbQm3xZ+2/9P7OpGf9AM42+4SB1TLQ8htK66S43XaT14J91+yjNDtLA X-Received: by 10.28.181.68 with SMTP id e65mr16061420wmf.132.1474908944513; Mon, 26 Sep 2016 09:55:44 -0700 (PDT) Received: from xps13.localnet (184.203.134.77.rev.sfr.net. [77.134.203.184]) by smtp.gmail.com with ESMTPSA id gr7sm23309578wjc.1.2016.09.26.09.55.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Sep 2016 09:55:43 -0700 (PDT) From: Thomas Monjalon To: "Iremonger, Bernard" Cc: "Richardson, Bruce" , "Wiles, Keith" , Yuanhan Liu , "Loftus, Ciara" , dev@dpdk.org Date: Mon, 26 Sep 2016 18:55:42 +0200 Message-ID: <1565378.1kcpGsyC38@xps13> User-Agent: KMail/4.14.10 (Linux/4.5.4-1-ARCH; KDE/4.14.11; x86_64; ; ) In-Reply-To: <8CEF83825BEC744B83065625E567D7C21A08D485@IRSMSX108.ger.corp.intel.com> References: <1473774463-26966-1-git-send-email-ciara.loftus@intel.com> <20160926143430.GA20484@bricha3-MOBL3> <8CEF83825BEC744B83065625E567D7C21A08D485@IRSMSX108.ger.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id 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: Mon, 26 Sep 2016 16:55:45 -0000 2016-09-26 16:24, Iremonger, Bernard: > Hi Bruce, Thomas, > > > > > Subject: Re: [dpdk-dev] [PATCH] net/vhost: Add function to retreive the 'vid' > > for a given port id > > > > On Mon, Sep 26, 2016 at 04:26:27PM +0200, Thomas Monjalon wrote: > > > 2016-09-26 14:18, Bruce Richardson: > > > > On Mon, Sep 26, 2016 at 03:12:01PM +0200, Thomas Monjalon wrote: > > > > > 2016-09-23 21:23, Wiles, Keith: > > > > > > On Sep 23, 2016, at 12:26 AM, Yuanhan Liu > > wrote: > > > > > > > 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? > > > > > > > > > > > > I do not see a need in the TAP PMD other then returning the FD for > > TUN/TAP device. Not sure what any application would need with the FD > > here, as it could cause some problems. > > > > > > > > > > > > This feels like we are talking about a IOCTL like generic interface into > > the PMD. Then we can add new one types and reject types in the PMD that > > are not supported. Would this not be a better method for all future PMD > > APIs? > > > > > > > > > > > > Here is just a thought as to how to solve this problem without a PMD > > specific API. A number of current ethdev APIs could be removed to use the > > API below. The APIs would be removed from ethdev structure and have the > > current APIs use the API below. I know some are not happy with number of > > APIs in the ethdev structure. > > > > > > > > > > > > The API could be something like this: > > > > > > struct rte_tlv { /* Type/Length/Value like structure */ > > > > > > uint16_t type; /* Type of command */ > > > > > > uint16_t len; /* Length of data section on input and on output > > */ > > > > > > uint16_t tlen; /* Total or max length of data buffer */ > > > > > > uint8_t data[0]; > > > > > > }; > > > > > > > > > > > > int rte_eth_dev_ioctl(int pid, int qid, struct rte_tlv *tlv); > > > > > > > > > > Yes we are talking about having some specific functions per driver > > > > > which are not defined in the generic ethdev layer. > > > > > We need only one function in ethdev to give access to driver-specific > > API. > > > > > My idea is to convert the port id into an opaque handler. > > > > > Your idea is to use the port id in an ioctl like function. > > > > > > > > > > About the implementation, these are the 2 differences between my > > > > > proposal and yours: > > > > > - You use the well known port id, whereas I need another handler > > > > > which is understood by the driver. > > > > > - You need to build a message string which will be decoded by the > > driver. > > > > > I propose to directly offer some specific functions in the drivers > > > > > which are more convenient to use and easier for code review/debug. > > > > > > > > > > No conclusion here. I just want to make sure that we are on the > > > > > same page, and would like to have feedback from others. Thanks > > > > > > > > I personally don't like the idea of having a generic IOCTL in > > > > ethdev. If you want to have NIC-specific functions provided by a > > > > driver, that is fine, but any app using those is going to be limited to > > working only with that driver. > > > > > > > > In that case, since the driver in question is known, I don't see any > > > > reason to go through the ethdev layer. I think it would be much > > > > clearer to have the app instead include the driver's header file and > > > > call the driver function directly. The #include at the top of the > > > > file makes the dependency very clear, and having a function name > > > > instead of IOCTL with magic command numbers allows the action take by > > the function to be clearer too. > > > > > > So you are against an IOCTL API. Me too. > > > You agree that an application can be NIC-specific and include an > > > header file given by the driver to offer very specific features. Me too. > > > > > > My proposal was to convert the port id to an opaque pointer as handler > > > of these driver APIs. After an offline discussion, we agreed that it > > > is not necessary because drivers manage rte_eth_dev struct and port_id > > > through > > > lib/librte_ether/rte_ethdev.h: extern struct rte_eth_dev > > > rte_eth_devices[]; > > > > > > > +1. I agree with your proposal, and I also agree that no ethdev changes > > +are > > necessary to support drivers having their own private functions. > > I am not sure what has been agreed here. > > Looking at the code in struct rte_eth_dev{} > > struct rte_eth_dev{ > ... > const struct eth_dev_ops *dev_ops; /**< Functions exported by PMD */ > ... > } > > The driver functions are only accessible if they are in struct eth_dev_ops. > I thought the issue here was that driver functions should not be added to the struct eth_dev_ops. > Hence the need for an eth_dev API to return a pointer to a driver dev_ops structure containing the driver functions. An example from an application point of view: #include rte_pmd_ixgbe_vf_ping(port_id, vf_id);