Date: Wed, 21 Jun 2000 11:53:00 +1200 From: Dave Preece <dave.preece@kbgroup.co.nz> To: Marc Nicholas <marc@netstor.com> Cc: freebsd-hackers@freebsd.org Subject: RE: IP checksum offloading with intel 82559 fast ethernet. Message-ID: <67B808B0DD93D211ABEE0000B498356B02BCD2@internet.kbgroup.co.nz>
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> 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
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