From owner-freebsd-hackers  Tue May 29 13: 9:16 2001
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Date: Tue, 29 May 2001 22:11:07 +0200
From: Jesper Skriver <jesper@skriver.dk>
To: Bob Willcox <bob@immure.com>
Cc: hackers list <freebsd-hackers@freebsd.org>
Subject: Re: How to disable software TCP checksumming?
Message-ID: <20010529221107.C49875@skriver.dk>
References: <20010529144114.I19771@luke.immure.com>
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In-Reply-To: <20010529144114.I19771@luke.immure.com>; from bob@immure.com on Tue, May 29, 2001 at 02:41:14PM -0500
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On Tue, May 29, 2001 at 02:41:14PM -0500, Bob Willcox wrote:
> Hi,
> 
> I am working on a device driver for a GSN adapter that has hardware CRC
> checking and need to know if there is a way to disable the software CRC
> checking for TCP?  This is on a FreeBSD 4.2-stable system.

Not without modifying the source, the below should do it from a
quick look.

Index: src/sys/netinet/tcp_input.c
===================================================================
RCS file: /home/ncvs/src/sys/netinet/tcp_input.c,v
retrieving revision 1.130
diff -u -r1.130 tcp_input.c
--- src/sys/netinet/tcp_input.c	2001/05/29 19:54:45	1.130
+++ src/sys/netinet/tcp_input.c	2001/05/29 20:07:22
@@ -401,6 +401,7 @@
 	th = (struct tcphdr *)((caddr_t)ip + off0);
 	tlen = ip->ip_len;
 
+#if 0
 	if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
 		if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
                 	th->th_sum = m->m_pkthdr.csum_data;
@@ -423,6 +424,7 @@
 		tcpstat.tcps_rcvbadsum++;
 		goto drop;
 	}
+#endif
 #ifdef INET6
 	/* Re-initialization for later version check */
 	ip->ip_v = IPVERSION;

/Jesper

-- 
Jesper Skriver, jesper(at)skriver(dot)dk  -  CCIE #5456
Work:    Network manager   @ AS3292 (Tele Danmark DataNetworks)
Private: FreeBSD committer @ AS2109 (A much smaller network ;-)

One Unix to rule them all, One Resolver to find them,
One IP to bring them all and in the zone to bind them.

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