netdev - Re: [PATCH net-next 01/14] net: txgbe: Add build support for txgbe ethernet driver

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Message-ID: <Yn0tML4HmEAnNARr@lunn.ch>
Date:   Thu, 12 May 2022 17:52:16 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jiawen Wu <jiawenwu@...stnetic.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 01/14] net: txgbe: Add build support for txgbe
 ethernet driver

> +Disable LRO if enabling ip forwarding or bridging
> +-------------------------------------------------
> +WARNING: The txgbe driver supports the Large Receive Offload (LRO) feature.
> +This option offers the lowest CPU utilization for receives but is completely
> +incompatible with *routing/ip forwarding* and *bridging*. If enabling ip
> +forwarding or bridging is a requirement, it is necessary to disable LRO using
> +compile time options as noted in the LRO section later in this document. The
> +result of not disabling LRO when combined with ip forwarding or bridging can be
> +low throughput or even a kernel panic.

Please could you tell us more. Is this a hardware/firmware issue? A
know bug in your driver you cannot find?

And why is it a compile time option, not ethtool -k?

> +ethtool
> +-------
> +The driver utilizes the ethtool interface for driver configuration and
> +diagnostics, as well as displaying statistical information. The latest
> +ethtool version is required for this functionality.

And will this still be true in 5 years time?

> +Disable GRO when routing/bridging
> +---------------------------------
> +Due to a known kernel issue, GRO must be turned off when routing/bridging. GRO
> +can be turned off via ethtool::

What kernel issue?

     Andrew