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

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Date: Fri, 5 Jan 2024 01:00:38 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Vladimir Oltean <olteanv@...il.com>
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

On Thu, Jan 4, 2024 at 1:24 AM Vladimir Oltean <olteanv@...il.com> wrote:
> 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?

Wrapped in DSA, rtl_a_4.

Yours,
Linus Walleij