From owner-freebsd-stable@FreeBSD.ORG Sun Feb 8 10:43:25 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5A74D1065672 for ; Sun, 8 Feb 2009 10:43:25 +0000 (UTC) (envelope-from peter@vk2pj.dyndns.org) Received: from mail36.syd.optusnet.com.au (mail36.syd.optusnet.com.au [211.29.133.76]) by mx1.freebsd.org (Postfix) with ESMTP id E0FC68FC19 for ; Sun, 8 Feb 2009 10:43:24 +0000 (UTC) (envelope-from peter@vk2pj.dyndns.org) Received: from test71.vk2pj.dyndns.org (c122-106-216-167.belrs3.nsw.optusnet.com.au [122.106.216.167]) by mail36.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id n18AgrQ6006603 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 8 Feb 2009 21:42:54 +1100 X-Bogosity: Ham, spamicity=0.000000 Received: from test71.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by test71.vk2pj.dyndns.org (8.14.3/8.14.3) with ESMTP id n18AgrXi064626; Sun, 8 Feb 2009 21:42:53 +1100 (EST) (envelope-from peter@test71.vk2pj.dyndns.org) Received: (from peter@localhost) by test71.vk2pj.dyndns.org (8.14.3/8.14.3/Submit) id n18Agrrk064625; Sun, 8 Feb 2009 21:42:53 +1100 (EST) (envelope-from peter) Date: Sun, 8 Feb 2009 21:42:53 +1100 From: Peter Jeremy To: Danny Braniss Message-ID: <20090208104253.GB31876@test71.vk2pj.dyndns.org> References: <20090208091656.GA31876@test71.vk2pj.dyndns.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ZoaI/ZTpAVc4A5k6" Content-Disposition: inline In-Reply-To: X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.18 (2008-05-17) Cc: freebsd-stable@freebsd.org Subject: Re: impossible packet length ... X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 Feb 2009 10:43:25 -0000 --ZoaI/ZTpAVc4A5k6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2009-Feb-08 11:31:45 +0200, Danny Braniss wrote: >Q: with rxcsum on, and a bad checksum packet is received, is it > dropped by the NIC? if not, then it somewhat explains the behaviour If checksum offloading is working correctly then a bad packet should be dropped by the NIC. If checksum offloading isn't working correctly then you can wind up in the situation where both the NIC and the driver think the other party has verified the checksum. It's also possible that you may be running into corruption during DMA transfer =66rom the NIC to RAM. ISTR there have been some issues reported recently with checksum offloading on some NICs - though I don't have details to hand - you might like to search the lists. >changing the nic is tough, but if needed will be done.=20 If disabling checksum offloading fixes the problem and the additional CPU load is acceptable (at least until you find a real fix) then there's no need to change NICs. --=20 Peter Jeremy --ZoaI/ZTpAVc4A5k6 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (FreeBSD) iEYEARECAAYFAkmOty0ACgkQ/opHv/APuIecbgCeKUBqmqvYE/t/UJv/Z03h7ZaM KnUAn0yYadZJgChKjSUatT1NgPAAkYJk =YD1D -----END PGP SIGNATURE----- --ZoaI/ZTpAVc4A5k6--