From owner-freebsd-net@FreeBSD.ORG  Sat Dec 20 21:31:43 2008
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 6D5261065673
	for <freebsd-net@freebsd.org>; Sat, 20 Dec 2008 21:31:43 +0000 (UTC)
	(envelope-from Michael.Tuexen@lurchi.franken.de)
Received: from mail-n.franken.de (drew.ipv6.franken.de
	[IPv6:2001:638:a02:a001:20e:cff:fe4a:feaa])
	by mx1.freebsd.org (Postfix) with ESMTP id 0405B8FC17
	for <freebsd-net@freebsd.org>; Sat, 20 Dec 2008 21:31:42 +0000 (UTC)
	(envelope-from Michael.Tuexen@lurchi.franken.de)
Received: from [IPv6:2002:508f:c392::21e:c2ff:fe00:76c8] (unknown
	[IPv6:2002:508f:c392:0:21e:c2ff:fe00:76c8])
	by mail-n.franken.de (Postfix) with ESMTP id 220E71C0C0BD4
	for <freebsd-net@freebsd.org>; Sat, 20 Dec 2008 22:31:40 +0100 (CET)
Message-Id: <FE14F235-917E-4B3C-A7DB-55E26E0BB9E4@lurchi.franken.de>
From: =?ISO-8859-1?Q?Michael_T=FCxen?= <Michael.Tuexen@lurchi.franken.de>
To: FreeBSD Net <freebsd-net@freebsd.org>
Content-Type: text/plain; charset=US-ASCII; format=flowed
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0 (Apple Message framework v930.3)
Date: Sat, 20 Dec 2008 22:31:39 +0100
X-Mailer: Apple Mail (2.930.3)
Subject: Checksum offloading
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: Sat, 20 Dec 2008 21:31:43 -0000

Dear all,

I'm currently analyzing how TCP/UDP checksum offloading works
to find the best way to add SCTP checksum offloading.

sys/mbuf.h has constants:
#define	CSUM_IP			0x0001		/* will csum IP */
#define	CSUM_TCP		0x0002		/* will csum TCP */
#define	CSUM_UDP		0x0004		/* will csum UDP */
which are used to signal which offloading is supported by the drive.
But, if I understand the code correctly, this only
applies to UDP/IPv4 and TCP/IPv4.
What about IPv6? Would this require flags like CSUM_TCP6 and CSUM_UDP6
to signal that also offloading of UDP/IPv6 and TCP/IPv6 is supported?

I'm asking this because we want to add CRC offloading for SCTP/IPv4
and SCTP/IPv6. We could only add one flag CSUM_SCTP and use it
for IPv4 and IPv6 ar two flags CSUM_SCTP4 and CSUM_SCTP6...

Best regards
Michael