Date:   Sat, 22 Apr 2017 04:07:06 +0300
From:   Saeed Mahameed <saeedm@....mellanox.co.il>
To:     Ian Kumlien <ian.kumlien@...il.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Matan Barak <matanb@...lanox.com>
Cc:     David Miller <davem@...emloft.net>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [RFC] change the default Kconfig value of mlx5_en

On Sat, Apr 22, 2017 at 3:47 AM, Ian Kumlien <ian.kumlien@...il.com> wrote:
> On Sat, Apr 22, 2017 at 2:34 AM, Saeed Mahameed
> <saeedm@....mellanox.co.il> wrote:
>> On Sat, Apr 22, 2017 at 2:10 AM, Ian Kumlien <ian.kumlien@...il.com> wrote:
>>> Sorry,
>>>
>>> Back again, fighting cold, hot whiskey has been consumed...
>>>
>>> Something like this would perhaps be a better solution:
>>>
>>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c
>>> b/drivers/net/ethernet/mellanox/mlx5/core/main.c
>>> index 60154a175bd3..fe192e247601 100644
>>> --- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
>>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
>>> @@ -1139,6 +1139,10 @@ static int mlx5_load_one(struct mlx5_core_dev
>>> *dev, struct mlx5_priv *priv,
>>>
>>>  #ifdef CONFIG_MLX5_CORE_EN
>>>         mlx5_eswitch_attach(dev->priv.eswitch);
>>> +#else
>>> +       if (MLX5_CAP_GEN(dev, port_type) == MLX5_CAP_PORT_TYPE_ETH) {
>>> +               dev_info(&pdev->dev, "Ethernet device discovered but
>>> support not enabled in kernel.");
>>> +       }
>>>  #endif
>>>
>>
>> Currently both MLX5_CORE=n and MLX5_CORE_EN=n as a default, the issue
>> you are seeing can occur only if you explicitly  set MLX5_CORE=y and
>> MLX5_CORE=n, Why would someone do this if he knows he wants Ethernet
>> support as well ? IMHO this print is redundant .
>
> Well, I'm running a prebuilt kernel - which was configured this way,
> and since there
> is no mlx5_en module and it does state that the link is "Ethernet", it
> just looks like the
> driver is broken or in some kind of really weird state.
>
>> Anyway, Are you looking for RDMA support over ethernet (RoCE) ? and
>> you are not interested to have ethernet netdev support ?
>
> ? RDMA is something we'll look at in the future, right now, having the
> nics actually
> work as nics is a priority ;)
>

I see, i just wanted to understand your situation :)

>> if yes, I think this is something that can be achieved, but the
>> question is do we really need this ?
>
> It's really weird to see the driver load, to see everything register
> and have no feedback.
>

So, in your case you have mlx5 core support without MLX5_CORE_EN which
provides the eswitch and netdev functionality in ethernet.

But you will still have mlx5_ib register an RDMA interface and
theoretically it should work, the only thing you won't see is a
netdevice.

The weird thing is that you don't see a link up on the RDMA interface,
Leon/Matan can you please look into this ? do we really need a netdev
to have a functioning RDMA logical link in ethernet ?

> Including no network devices, but if you run the Infiniband commands,
> they tell you that
> you are connected to Ethernet but that the device is down and disabled.
>
> To me, down and disabled is not the same as in "Ethernet support is
> not included" =)
>
> Basically, i would hate for someone else to end up in the same
> situation since you only
> get guides on how to enable infiniband/RDMA but what you really want
> to do at that point
> is to disable it and see if that gives you your network devices back =)
>

Yes this is misleading, Maybe your kernel log warning is not so bad
after all, but let me dig more into this.
I will get back to you next week.

> I have had similar issues with some connectx3 devices while playing at
> home but i suspect
> that it's just a limitation of OFED packages available for the dist I'm running.

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