Date: Mon, 9 Apr 2007 15:26:19 +0900 From: Pyun YongHyeon <pyunyh@gmail.com> To: Harald Schmalzbauer <harry@schmalzbauer.de> Cc: freebsd-bugs@FreeBSD.org Subject: Re: kern/111384: msk hw checksum problem Message-ID: <20070409062618.GA41379@cdnetworks.co.kr> In-Reply-To: <200704082120.l38LKA3v058525@freefall.freebsd.org> References: <200704082120.l38LKA3v058525@freefall.freebsd.org>
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On Sun, Apr 08, 2007 at 09:20:10PM +0000, Harald Schmalzbauer wrote: > The following reply was made to PR kern/111384; it has been noted by GNATS. > > From: Harald Schmalzbauer <harry@schmalzbauer.de> > To: FreeBSD-gnats-submit@freebsd.org, freebsd-bugs@freebsd.org > Cc: > Subject: Re: kern/111384: msk hw checksum problem > Date: Sun, 8 Apr 2007 22:58:12 +0200 > > I did a quick check on 6.2-stable and couldn't see the symptom (no connection > to freeshports). But I haven't captured traffic, so I can't guarantee that > the "TCP checksum mismatch" doesn't aplly to 6.2-stable as well. > Hmm, it's odd that STABLE works wihtout issues. msk(4) in STABLE takes the same code path so it shoud have the issue too if msk(4) in HEAD also has checksum offload issues. The reason of sending Winwdos probe message comes from the other party' zero window advertisement in SYN + ACK packet. As you know TCP can't send more data except window probing message if it recevied zero window advirtisement. Maybe the other party(www.freshports.org) advertise its window update packet if it received correct window probe message from msk(4). Since msk(4) failed to generate correct TCP cheksum the other party didn't receive the probe message and you've lost connection here. Anyway I was able to reproduce the issue on HEAD but I have no idea atm. Just padding with zeros to make it 60 bytes frame didn't work and I wonder how it could work in STABLE. > -Harry > -- Regards, Pyun YongHyeon
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