Date: Mon, 13 May 2002 13:09:24 -0700 From: David Greenman-Lawrence <dg@root.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: Matthew Dillon <dillon@apollo.backplane.com>, jamie@tridentmicrosystems.co.uk, freebsd-hackers@FreeBSD.ORG Subject: Re: Broadcom BCM5701 Chipset problems Message-ID: <20020513130924.W72322@nexus.root.com> In-Reply-To: <3CE01A3A.AAB85F64@mindspring.com>; from tlambert2@mindspring.com on Mon, May 13, 2002 at 12:55:38PM -0700 References: <20020513115600.A50967@mufuf.trident-uk.co.uk> <3CDFF60C.48A2EA65@mindspring.com> <20020513102526.H72322@nexus.root.com> <200205131758.g4DHwJFj068941@apollo.backplane.com> <3CE00B14.E8CA43A8@mindspring.com> <200205131901.g4DJ1U8s069604@apollo.backplane.com> <3CE01595.D045B70D@mindspring.com> <20020513124807.R72322@nexus.root.com> <3CE01A3A.AAB85F64@mindspring.com>
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>David Greenman-Lawrence wrote: >> >Was the result a rejected packet that didn't get transferred, or >> >transferred packets with bad checksums? >> > >> >If the latter, then it's workaroundable in software, which might >> >be worth doing... if only rechecking packets with bad checksums. >> >I fear the former makes more sense, though. 8-(. >> >> The chip would calculate the wrong checksum and basically say the packet >> was bad when it was good (and by inference, good when it was bad). I was not >> able to figure out what they got wrong in the algorithm, but if that were >> known, then it is conceivable that the problem could be fixed in software. > >Was the "bad packet" DMA'ed in anyway, or just dropped at the card? The card doesn't drop the packet if the IP/TCP checksum is wrong. In my tests, I did a software checksum on the supposedly bad packet, and found it to be good every time. So it DMA's correctly, the checksum is just calculated incorrectly by the hardware. -DG David Greenman-Lawrence Co-founder, The FreeBSD Project - http://www.freebsd.org President, TeraSolutions, Inc. - http://www.terasolutions.com President, Download Technologies, Inc. - http://www.downloadtech.com Pave the road of life with opportunities. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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