netdev - Re: [PATCH net-next] net: Make RX-FCS and LRO mutually exclusive

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Date:   Mon, 05 Mar 2018 10:27:04 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     galp@...lanox.com
Cc:     netdev@...r.kernel.org, tariqt@...lanox.com
Subject: Re: [PATCH net-next] net: Make RX-FCS and LRO mutually exclusive

From: Gal Pressman <galp@...lanox.com>
Date: Sun,  4 Mar 2018 14:12:04 +0200

> LRO and RX-FCS offloads cannot be enabled at the same time since it is
> not clear what should happen to the FCS of each coalesced packet.
> The FCS is not really part of the TCP payload, hence cannot be merged
> into one big packet. On the other hand, providing one big LRO packet
> with one FCS contradicts the RX-FCS feature goal.
> 
> Use the fix features mechanism in order to prevent intersection of the
> features and drop LRO in case RX-FCS is requested.
> 
> Enabling RX-FCS while LRO is enabled will result in:
> $ ethtool -K ens6 rx-fcs on
> Actual changes:
> large-receive-offload: off [requested on]
> rx-fcs: on
> 
> Signed-off-by: Gal Pressman <galp@...lanox.com>
> Reviewed-by: Tariq Toukan <tariqt@...lanox.com>

Agreed, having these two options enabled at the same time doesn't
make any sense.

Applied.

Probably need to add the same restriction for HW GRO.