Date: Tue, 20 Jun 2000 16:56:31 -0700 From: Paul Saab <paul@mu.org> To: Matthew Jacob <mjacob@feral.com> Cc: Dave Preece <dave.preece@kbgroup.co.nz>, Marc Nicholas <marc@netstor.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: IP checksum offloading with intel 82559 fast ethernet. Message-ID: <20000620165630.A61265@elvis.mu.org> In-Reply-To: <Pine.BSF.4.05.10006201637470.12031-100000@semuta.feral.com>; from mjacob@feral.com on Tue, Jun 20, 2000 at 04:42:12PM -0700 References: <67B808B0DD93D211ABEE0000B498356B02BCD2@internet.kbgroup.co.nz> <Pine.BSF.4.05.10006201637470.12031-100000@semuta.feral.com>
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The checksome off loading for the Intel gigabit card is broken. All you get is the checksum of the frame, so it really isn't all that useful. paul Matthew Jacob (mjacob@feral.com) wrote: > > > (I'm the wx author)... I want to do checksum offloading too at some point. > > There's been some work done on this by Andrew Gallatin and Ken Merry amongst > others insofar as I recall, but I don't believe it's been checked in. Let me > see if I can dig up the mail.. > > Everyone's at Usenix this week && next, so don't expect too much of a > response. > > -matt > > > On Wed, 21 Jun 2000, Dave Preece wrote: > > > > Don't some of the Gigabit FreeBSD drivers actually utilize > > > the on-board > > > checksum processing??? > > > > Hmmmm, can't see anything specific.... Looking at if_wx.c we have a function > > wx_start(ifp) where ifp is an ifnet pointer. ifnet has a member if_snd, of > > type ifqueue (according to the man page). And ifqueue is a safe looking > > memory buffer, but no actual statement as to whether we are expected to put > > raw packets on the queue or.... what. Presumably entire ethernet frames are > > put on the queue so we can spoof ethernet mac addresses occasionally - but > > no real way of indicating to the card that we have put an IP packet on with > > no checksum (and could you calculate it for me please). > > > > As an aside, if checksum calculations were offloadable via a call across PCI > > (i.e. send raw packet, get packet back with tcp calculated, queue packet for > > delivery), then it's a bit touch and go as to whether this is actually a > > good idea - given that we'll start to load up PCI quite badly doing this. > > > > > Nice to see someone keeping our drivers fresh :-) > > > > Oh, no. I wish. I'm well off the end of my abilities here, but clearly into > > what I 'owe' the community in general. Hopefully I'll get there at some > > time. > > > > > -marc > > > > Dave > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-hackers" in the body of the message > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message -- Paul Saab Technical Yahoo paul@mu.org - ps@yahoo-inc.com - ps@freebsd.org Do You .. uhh .. Yahoo!? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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