From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id E66E72BA6 for ; Mon, 26 Sep 2016 18:24:13 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP; 26 Sep 2016 09:24:04 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.30,400,1470726000"; d="scan'208";a="766101323" Received: from irsmsx109.ger.corp.intel.com ([163.33.3.23]) by FMSMGA003.fm.intel.com with ESMTP; 26 Sep 2016 09:24:01 -0700 Received: from irsmsx112.ger.corp.intel.com (10.108.20.5) by IRSMSX109.ger.corp.intel.com (163.33.3.23) with Microsoft SMTP Server (TLS) id 14.3.248.2; Mon, 26 Sep 2016 17:24:00 +0100 Received: from irsmsx108.ger.corp.intel.com ([169.254.11.164]) by irsmsx112.ger.corp.intel.com ([169.254.1.170]) with mapi id 14.03.0248.002; Mon, 26 Sep 2016 17:24:00 +0100 From: "Iremonger, Bernard" To: "Richardson, Bruce" , Thomas Monjalon CC: "Wiles, Keith" , Yuanhan Liu , "Loftus, Ciara" , "dev@dpdk.org" Thread-Topic: [dpdk-dev] [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id Thread-Index: AQHSGANZn138XWP9z0qzxeD083X686CL8Etw Date: Mon, 26 Sep 2016 16:24:00 +0000 Message-ID: <8CEF83825BEC744B83065625E567D7C21A08D485@IRSMSX108.ger.corp.intel.com> References: <1473774463-26966-1-git-send-email-ciara.loftus@intel.com> <1895719.0W7iI9zMqJ@xps13> <20160926131835.GA21308@bricha3-MOBL3> <1649619.cdBSfnkg7V@xps13> <20160926143430.GA20484@bricha3-MOBL3> In-Reply-To: <20160926143430.GA20484@bricha3-MOBL3> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiZTg0MDkwMWItMTI5NS00ZjhiLWFlZWQtMmZlNjRiNzFmODU3IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX0lDIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE1LjkuNi42IiwiVHJ1c3RlZExhYmVsSGFzaCI6IlRjRm5FRVp6ZEQ4YjhCRWNEK01veE9QWHc0WmxwaWxsc1c4Y1hvZUpEYTg9In0= x-ctpclassification: CTP_IC x-originating-ip: [163.33.239.182] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 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 16:24:14 -0000 Hi Bruce, Thomas, > Subject: Re: [dpdk-dev] [PATCH] net/vhost: Add function to retreive the '= vid' > for a given port id >=20 > 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 i= s 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 underlyi= ng > 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 fo= r > 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 interfa= ce 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-specif= ic > 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[]; > > >=20 > +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 s= tructure containing the driver functions.=20 Regards, Bernard.