From owner-freebsd-net@FreeBSD.ORG  Wed Jul  9 21:26:54 2008
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C909B1065671
	for <net@freebsd.org>; Wed,  9 Jul 2008 21:26:54 +0000 (UTC)
	(envelope-from gnn@neville-neil.com)
Received: from proxy.meer.net (proxy.meer.net [64.13.141.13])
	by mx1.freebsd.org (Postfix) with ESMTP id A2FC28FC14
	for <net@freebsd.org>; Wed,  9 Jul 2008 21:26:54 +0000 (UTC)
	(envelope-from gnn@neville-neil.com)
Received: from mail.meer.net (mail.meer.net [64.13.141.3])
	by proxy.meer.net (8.14.2/8.14.2) with ESMTP id m69LQqjQ076213
	for <net@freebsd.org>; Wed, 9 Jul 2008 14:26:54 -0700 (PDT)
	(envelope-from gnn@neville-neil.com)
Received: from mail2.meer.net (mail2.meer.net [64.13.141.16])
	by mail.meer.net (8.13.3/8.13.3/meer) with ESMTP id m69LPqfd086756
	for <net@freebsd.org>; Wed, 9 Jul 2008 14:25:52 -0700 (PDT)
	(envelope-from gnn@neville-neil.com)
Received: from minion.local.neville-neil.com
	(209.249.190.254.available.above.net [209.249.190.254] (may be
	forged)) (authenticated bits=0)
	by mail2.meer.net (8.14.1/8.14.1) with ESMTP id m69LPqgm040183
	for <net@freebsd.org>; Wed, 9 Jul 2008 14:25:52 -0700 (PDT)
	(envelope-from gnn@neville-neil.com)
Date: Wed, 09 Jul 2008 17:25:51 -0400
Message-ID: <m2fxqilpgg.wl%gnn@neville-neil.com>
From: gnn@freebsd.org
To: net@freebsd.org
User-Agent: Wanderlust/2.15.5 (Almost Unreal) SEMI/1.14.6 (Maruoka)
	FLIM/1.14.9 (=?ISO-8859-4?Q?Goj=F2?=) APEL/10.7 Emacs/22.1.50
	(i386-apple-darwin8.11.1) MULE/5.0 (SAKAKI)
MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka")
Content-Type: text/plain; charset=US-ASCII
X-Canit-CHI2: 0.50
X-Bayes-Prob: 0.5 (Score 0, tokens from: )
X-Spam-Score: 0.10 () [Tag at 5.00] COMBINED_FROM
X-CanItPRO-Stream: default
X-Canit-Stats-ID: 902236 - a23f3521c173
X-Scanned-By: CanIt (www . roaringpenguin . com) on 64.13.141.13
Cc: 
Subject: What's the deal with hardware checksum and net.inet.udp.checksum?
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 09 Jul 2008 21:26:54 -0000

I would assume that if a card, say the em, has hardware TX checksum
that the UDP checksum could be calculated by the hardware, but this
seems not to be the case.  The manual pages are unhelpful in this regard.

Thanks,
George