(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
>
>
>
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