From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Subject: Re: [RFC] eal/memory: introducing an option to set iova
 as va
Date: Tue, 6 Jun 2017 16:11:55 +0530
Message-ID: <20170606104154.GB20333@jerin>
References: <20170524161101.22863-1-santosh.shukla@caviumnetworks.com>
 <79f1e8ae-d2cc-e49e-a17d-73c7185b26f8@caviumnetworks.com>
 <20170602092735.GA51388@bricha3-MOBL3.ger.corp.intel.com>
 <e2aec279-2c50-135c-ba07-c21867a1bb8f@caviumnetworks.com>
 <20170606095719.GA50888@bricha3-MOBL3.ger.corp.intel.com>
 <20170606101308.GL18840@bidouze.vm.6wind.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
Cc: Bruce Richardson <bruce.richardson@intel.com>,
 santosh <santosh.shukla@caviumnetworks.com>, thomas@monjalon.net,
 dev@dpdk.org, hemant.agrawal@nxp.com
To: =?iso-8859-1?Q?Ga=EBtan?= Rivet <gaetan.rivet@6wind.com>
Return-path: <dev-bounces@dpdk.org>
Received: from NAM02-CY1-obe.outbound.protection.outlook.com
 (mail-cys01nam02on0087.outbound.protection.outlook.com [104.47.37.87])
 by dpdk.org (Postfix) with ESMTP id B19754CE4
 for <dev@dpdk.org>; Tue,  6 Jun 2017 12:42:14 +0200 (CEST)
Content-Disposition: inline
In-Reply-To: <20170606101308.GL18840@bidouze.vm.6wind.com>
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

-----Original Message-----
> Date: Tue, 6 Jun 2017 12:13:08 +0200
> From: Gaëtan Rivet <gaetan.rivet@6wind.com>
> To: Bruce Richardson <bruce.richardson@intel.com>
> Cc: santosh <santosh.shukla@caviumnetworks.com>, thomas@monjalon.net,
>  dev@dpdk.org, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com
> Subject: Re: [dpdk-dev] [RFC] eal/memory: introducing an option to set iova
>  as va
> User-Agent: Mutt/1.5.23 (2014-03-12)
> 
> > 
> > That sounds a more complete solution. However, it's probably a lot of
> > work to implement. :-)
> > 
> > I also wonder if we want to simplify things a little and disallow
> > mixed-mode operation i.e. all devices have to use UIO or all use VFIO?
> > Would that help to allow simplification or other options. Having a whole
> > new bus type seems strange for this. Can each bus just report whether
> > it's members require physical addresses. Then the EAL can manage a
> > single flag to report whether we are using VA or PA?
> > 
> 
> Implementing this at a bus level requires all buses to have drivers
> iterators, which are currently not exposed, or force all buses to
> actively report drivers capabilities upon successful probing. The former
> is a sizeable evolution while the latter leads to having duplicated code
> in all bus->probe() implementation, which seems unsound.
> 
> I may be mistaken, but is this iova mode not currently limited to
> VFIO? Should this API be made generic for all buses or is it only
> relevant to the PCI bus?
> 
> If it can stay specific to the PCI bus, then it should simplify greatly
> the implementation.

It not PCI bus specific. We can have VFIO platform bus too. NXP bus is a
VFIO platform bus. I think, This will help NXP bus as well as currently
they are using #ifdef scheme to select PA vs VA.