From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@scylladb.com>
Subject: Re: Having troubles binding an SR-IOV VF to
 uio_pci_generic on Amazon instance
Date: Thu, 1 Oct 2015 12:43:53 +0300
Message-ID: <560D0059.5050003@scylladb.com>
References: <560BD284.7040505@cloudius-systems.com>
 <20150930151632-mutt-send-email-mst@redhat.com>
 <560BDE24.8000308@scylladb.com>
 <20150930165359-mutt-send-email-mst@redhat.com>
 <560BF782.4070308@scylladb.com>
 <20150930175848-mutt-send-email-mst@redhat.com>
 <560C0171.7080507@scylladb.com> <20150930204016.GA29975@redhat.com>
 <20151001113828-mutt-send-email-mst@redhat.com> <560CF44A.60102@scylladb.com>
 <20151001120027-mutt-send-email-mst@redhat.com>
 <560CFB66.5050904@scylladb.com> <560CFFFF.4000601@6wind.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Cc: "dev@dpdk.org" <dev@dpdk.org>
To: Vincent JARDIN <vincent.jardin@6wind.com>,
 "Michael S. Tsirkin" <mst@redhat.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com
 [209.85.212.181]) by dpdk.org (Postfix) with ESMTP id B9D148DA4
 for <dev@dpdk.org>; Thu,  1 Oct 2015 11:43:56 +0200 (CEST)
Received: by wicge5 with SMTP id ge5so20982016wic.0
 for <dev@dpdk.org>; Thu, 01 Oct 2015 02:43:56 -0700 (PDT)
In-Reply-To: <560CFFFF.4000601@6wind.com>
List-Id: patches and discussions about DPDK <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>



On 10/01/2015 12:42 PM, Vincent JARDIN wrote:
> On 01/10/2015 11:22, Avi Kivity wrote:
>>> As far as I could see, without this kind of motivation, people do not
>>> even want to try.
>>
>> You are mistaken.  The problem is a lot harder than you think.
>>
>> People didn't go and write userspace drivers because they were lazy.
>> They wrote them because there was no other way.
>
> I disagree, it is possible to write a 'partial' userspace driver.
>
> Here it is an example:
>   http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4
>
> It benefits of the kernel's capabilities while the userland manages 
> only the IOs.
>

That is because the device itself contains an iommu.

> There were some tentative to get it for other (older) drivers, named 
> 'bifurcated drivers', but it is stalled.

IIRC they still exposed the ring to userspace.