From owner-freebsd-hackers Tue Jun 20 16:35:58 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from kbgroup.co.nz (gateway.kbgroup.co.nz [203.96.151.81]) by hub.freebsd.org (Postfix) with ESMTP id EA3C037B5A5 for ; Tue, 20 Jun 2000 16:35:54 -0700 (PDT) (envelope-from dave.preece@kbgroup.co.nz) Received: from kb_exchange.kbgroup.co.nz ([202.202.203.10]) by gateway.kbgroup.co.nz with ESMTP id <115201>; Wed, 21 Jun 2000 11:53:02 +1200 Received: by internet.kbgroup.co.nz with Internet Mail Service (5.5.2650.21) id ; Wed, 21 Jun 2000 11:45:28 +1200 Message-ID: <67B808B0DD93D211ABEE0000B498356B02BCD2@internet.kbgroup.co.nz> From: Dave Preece To: Marc Nicholas Cc: freebsd-hackers@freebsd.org Subject: RE: IP checksum offloading with intel 82559 fast ethernet. MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset="iso-8859-1" Date: Wed, 21 Jun 2000 11:53:00 +1200 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > 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