Date: Thu, 29 Oct 2020 14:36:23 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Kristof Provost <kp@FreeBSD.org> Cc: Carsten =?iso-8859-1?Q?B=E4cker?= <carbaecker@gmx.de>, freebsd-hackers@freebsd.org, freebsd-arm@freebsd.org Subject: Re: Problem with checksum offloading on RPi3 (PF + Jails involved) Message-ID: <20201029213622.GM31099@funkthat.com> In-Reply-To: <A3890336-BE8F-438C-8C3E-7B21FB729FCA@FreeBSD.org> References: <748edc3d-4ef7-c4de-291f-7c0b460a6052@gmx.de> <D8CE4762-4D94-47C7-A8D1-6C537766813B@FreeBSD.org> <5130ee46-5832-d4df-d774-c6bd32e10b30@gmx.de> <A3890336-BE8F-438C-8C3E-7B21FB729FCA@FreeBSD.org>
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Kristof Provost wrote this message on Thu, Oct 29, 2020 at 21:30 +0100:
> On 29 Oct 2020, at 16:30, Carsten Bäcker wrote:
> > Sure, i am willing to help.
> >
> > Device is a Raspberry Pi 3B (not +), using the onboard-ethernet.
> > I attached a bunch of information.
> >
> > Configuration is stripped down to the minimum required to reproduce
> > the
> > problem.
> >
> Okay, so that???s an SMC2 LAN9514_ETH device.
> That???s the dev/usb/net/if_smsc.c driver.
>
> However, before we dig into that driver we should make sure that we???re
> really looking at a checksum problem.
> It???s entirely normal for TX checksums to be incorrect when logged on
> the sending host itself (if the hardware does checksum offloading the
> checksum in the packet sent to the MAC is incorrect, and left to the
> hardware to fix).
>
> So, can you confirm that the `"[bad udp cksum 0xe58a -> 0x482d!]` you
> reported was on an inbound packet? And let???s be safe: try to capture
> packets on a different machine. That???ll give us the true packet, after
> the hardware has done checksum calculations.
One interesting point is that the smsc driver claims to not do TX offload,
and a brief check shows that it doesn't allow a user to set the TXCSUM.
I was thinking that the bad checksum might be due to tcpdump just
complaining.
does netstat -s show packets being received w/ bad checksums?
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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