Re: [dpdk-dev] discussion: creating a new class for vdpa driversxiao.w.wang@intel.com

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 12/8/19 10:06 AM, Matan Azrad wrote:
> From: Andrew Rybchenko
>> On 12/6/19 8:32 AM, Liang, Cunming wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: Bie, Tiwei <tiwei.bie@intel.com>
>>>> Sent: Friday, December 6, 2019 12:28 PM
>>>> To: Matan Azrad <matan@mellanox.com>
>>>> Cc: Wang, Xiao W <xiao.w.wang@intel.com>; Thomas Monjalon
>>>> <thomas@monjalon.net>; maxime.coquelin@redhat.com; Wang,
>> Zhihong
>>>> <zhihong.wang@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>;
>>>> Shahaf Shuler <shahafs@mellanox.com>; Ori Kam
>> <orika@mellanox.com>;
>>>> dev@dpdk.org; Slava Ovsiienko <viacheslavo@mellanox.com>; Asaf
>> Penso
>>>> <asafp@mellanox.com>; Olga Shern <olgas@mellanox.com>; Liang,
>> Cunming
>>>> <cunming.liang@intel.com>
>>>> Subject: Re: discussion: creating a new class for vdpa
>>>> driversxiao.w.wang@intel.com
>>>>
>>>> On Thu, Dec 05, 2019 at 01:26:36PM +0000, Matan Azrad wrote:
>>>>> Hi all
>>>>>
>>>>> As described in RFC “[RFC] net: new vdpa PMD for Mellanox devices”,
>>>>> a new vdpa drivers is going to be added for Mellanox devices –
>>>>> mlx5_vdpa
>>>>>
>>>>> The only vdpa driver now is the IFC driver that is located in net directory.
>>>>>
>>>>> The IFC driver and the new mlx5_vdpa driver provide the vdpa ops and
>>>>> not the eth_dev ops.
>>>>>
>>>>> All the others drivers in net provide the eth-dev ops.
>>>>>
>>>>> I suggest to create a new class for vdpa drivers, to move IFC to
>>>>> this class and to add the mlx5_vdpa to this class too.
>>>>>
>>>>> Later, all the new drivers that implements the vdpa ops will be
>>>>> added to the vdpa class.
>>>>
>>>> +1. Sounds like a good idea to me.
>>> +1
>>
>> vDPA drivers are vendor-specific and expected to talk to vendor NIC. I.e.
>> there are significant chances to share code with network drivers (e.g. base
>> driver). Should base driver be moved to drivers/common in this case or is it
>> still allows to have vdpa driver in drivers/net together with ethdev driver?
> 
> Yes, I think this should be the method, shared code should be moved to the drivers/common directory.
> I think there is a precedence with shared code in common which shares a vendor specific code between crypto and net.

I see motivation behind driver/vdpa. However, vdpa and net
drivers tightly related and I would prefer to avoid extra
complexity here. Right now simplicity over-weights for me.
No strong opinion on the topic, but it definitely requires
better and more clear motivation why a new class should be
introduced and existing drivers restructured.

> Actually, this is my plan to share mlx5 vdpa code with mlx5 net code by the drivers/common dir (see RFC).

I see.