From owner-freebsd-current@FreeBSD.ORG Fri May 23 11:34:19 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 618) id 0636037B401; Fri, 23 May 2003 11:34:19 -0700 (PDT) In-Reply-To: <200305230611.h4N6BUM7077910@gw.catspoiler.org> from Don Lewis at "May 22, 2003 11:11:30 pm" To: truckman@FreeBSD.org (Don Lewis) Date: Fri, 23 May 2003 11:34:18 -0700 (PDT) X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20030523183419.0636037B401@hub.freebsd.org> From: wpaul@FreeBSD.ORG (Bill Paul) cc: matt@hasta.se cc: drs@rucus.ru.ac.za cc: hrs@eos.ocn.ne.jp cc: current@FreeBSD.org Subject: Re: possible bug fix for 82550-based fxp packet truncation problem X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 May 2003 18:34:19 -0000 > > > > Just to let people know, I have been trying to investigate this, but > > my time has been somewhat limited lately. The original reason I turned > > off the IP checksumming on transmit was that there was one test case > > where the chip seemed to be generating improper checksums. That is, > > if you did something like: ping -s 1473 . This would result > > in a full sized frame, plus a small IP fragment containing just one > > byte of data. On the machine I used for testing, the small fragment > > was rejected by the host on the other side due to a bad header checksum. > > According to the second note in the Intel document that I cited, > hardware checksumming is unsupported in this case. Argh. No. IP checksumming == a checksum of the IP header only. The chip is perfectly capable of computing IP header checksums over fragments, and does so quite well, _except_ in this one bizarro case I encountered with tiny packets on this single P166 system. -Bill -- ============================================================================= -Bill Paul (510) 749-2329 | Senior Engineer, Master of Unix-Fu wpaul@windriver.com | Wind River Systems ============================================================================= "If stupidity were a handicap, you'd have the best parking spot." =============================================================================