netdev - Re: [RFC] change the default Kconfig value of mlx5

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Date:   Sat, 22 Apr 2017 02:47:23 +0200
From:   Ian Kumlien <ian.kumlien@...il.com>
To:     Saeed Mahameed <saeedm@....mellanox.co.il>
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 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 ;)

> 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.

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 =)

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.