netdev - Re: [PATCH net v5 1/2] net: ethernet: cortina: Drop software checksum and TSO

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Date: Thu, 4 Jan 2024 02:24:49 +0200
From: Vladimir Oltean <olteanv@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Hans Ulli Kroll <ulli.kroll@...glemail.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Household Cang <canghousehold@....com>,
	Romain Gantois <romain.gantois@...tlin.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net v5 1/2] net: ethernet: cortina: Drop software
 checksum and TSO

Hi Linus,

On Tue, Jan 02, 2024 at 09:34:25PM +0100, Linus Walleij wrote:
> That begs the question why large TCP or UDP packets also have to
> bypass the checksumming (like e.g. ICMP does). If the hardware is
> splitting it into smaller packets per-MTU setting, and checksumming
> them, why is this happening then? I don't know. I know it is needed,
> from tests: the OpenWrt webserver uhttpd starts sending big skb:s (up
> to 2047 bytes, the max MTU) and above 1514 bytes it starts to fail
> and hang unless the bypass bit is set: the frames are not getting
> through.

This uhttpd traffic is plain TCP, or TCP wrapped in DSA?