Re: Hardware capabilities and bonding offload

From: Jiri Pirko <jiri@resnulli.us>
To: Andrew Lunn <andrew@lunn.ch>
Cc: John Fastabend <john.fastabend@gmail.com>,
	Simon Horman <simon.horman@netronome.com>,
	Premkumar Jonnala <pjonnala@broadcom.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: Hardware capabilities and bonding offload
Date: Wed, 18 Nov 2015 15:29:23 +0100	[thread overview]
Message-ID: <20151118142923.GA2192@nanopsycho.orion> (raw)
In-Reply-To: <20151118140512.GC6123@lunn.ch>

Wed, Nov 18, 2015 at 03:05:12PM CET, andrew@lunn.ch wrote:
>> To be honest though this is more of an argument in theory versus
>> some existing management agent I know of today. If you need to do
>> bonding type X in your network and the particular switch doesn't support
>> it I'm not even sure what the mgmt layer is going to do. Maybe just
>> put the switch offline for that network segment.
>> 
>> If you leave the sw bit out in the first iteration I'm OK with that
>> we can easily add it when we have software that needs it.
>
>Taking a step back...
>
>Have we defined a consistent way for signalling:
>
>1) Failed to offload to the hardware, because the hardware cannot do
>   what you requested.
>2) Do this in software, rather than trying and failing to offload to
>   hardware.
>
>At least in DSA, we return EOPNOTSUP for 1).

Well for example in case of bonding there is quite impossible to do
things in software in case the hardware datapath simply cannot pass
packets to kernel. Driver should know and should forbid such
non-functional setup.

>
>   Andrew
>
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