Date: Mon, 13 May 2002 10:25:26 -0700 From: David Greenman-Lawrence <dg@root.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: jamie@tridentmicrosystems.co.uk, freebsd-hackers@freebsd.org Subject: Re: Broadcom BCM5701 Chipset problems Message-ID: <20020513102526.H72322@nexus.root.com> In-Reply-To: <3CDFF60C.48A2EA65@mindspring.com>; from tlambert2@mindspring.com on Mon, May 13, 2002 at 10:21:16AM -0700 References: <20020513115600.A50967@mufuf.trident-uk.co.uk> <3CDFF60C.48A2EA65@mindspring.com>
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>Jamie Heckford wrote: >> I read in the mailling lists mentions of hardware checksum problems >> with the chipset.. did anyone know what the final outcome with >> this problem was and if any changes had been MFC'd? > >The problems were only when coupled with VLAN tagging. > >I'm not sure if the 5701 was succeptible to the problem, or not. > >The patches disabled hardware checksumming. To fix the problem >on the card would require changes to the card firmware, at least >(hardware assisted checksum, subtracting out the VLAN encapsulation >incrementally; assumes that hardware can run a partial checksum, >and it's not tied to the buffer shift registers directly). > >If you aren't using VLAN tagging, you shouldn't care. No, that is absolutely not correct. The checksum problems happend in many situations, depending on the chipset and other factors. The problem that resulted in the commit to disable the receive hardware checksum was caused by small packets with certain byte patterns, NOT VLAN ENCAPSULATION. -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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