Date: Sat, 10 Jun 2000 09:41:34 -0700 From: Julian Elischer <julian@elischer.org> To: Roger Hardiman <roger@cs.strath.ac.uk> Cc: multimedia@freebsd.org, hackers@freebsd.org Subject: [Fwd: Re: Queries about Netgraph] Message-ID: <39426FBE.167EB0E7@elischer.org>
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I include an email from Benno Rice
who has done quite a bit of work on IrDA
using Netgraph.
You two should talk.
julian
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__--_|\ Julian Elischer
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( OZ ) World tour 2000
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Date: Wed, 31 May 2000 14:51:09 +1000
From: Benno Rice <benno@netizen.com.au>
To: Julian Elischer <julian@elischer.org>
Cc: Archie Cobbs <archie@whistle.com>
Subject: Re: Queries about Netgraph
Message-ID: <20000531145109.B411@netizen.com.au>
References: <200005301641.JAA32015@bubba.whistle.com> <3933F72A.41C67EA6@elischer.org>
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In-Reply-To: <3933F72A.41C67EA6@elischer.org>; from Julian Elischer on Tue, May 30, 2000 at 10:15:22AM -0700
On Tue, May 30, 2000 at 10:15:22AM -0700, Julian Elischer wrote:
> Archie Cobbs wrote:
> >
> > Benno Rice writes:
> > > I'm writing an IrDA stack using netgraph, and I was wanting to clarify
> > > a couple of small things.
>
> great. I was looking at doing similar.. I even have all the IrDA
> documentation on my machine here somewhere.
Yeah, I've downloaded all the specs. Should have IrLAP and part of
IrLMP working soon.
> > > Also, is it possible to pass such linked lists to other nodes?
> > >
> > > Basically one part of the IrLAP protocol is a process called "discovery"
> > > whereby a device discovers all the other devices within range. It then
> > > passes all the details of those devices to the IrLMP layer. I'd like to
> > > pass those details up as a linked list of structs.
> > >
> > > Is this doable in Netgraph or should I try another approach?
>
> I think I'd treat each discovered device as a separate message.
Yeah. Sounds best.
> I actually decided that IrDA wasn;t a very good fit
> for netgraph, but I can't remember why, maybe because IrDA
> has so many breakages of layering.
Doesn't seem so bad so far. There's just a lot of crosstalk between layers.
> > > (IrLAP == Infrared Link Access Protocol and IrLMP == Infrared Link Management
> > > Protocol btw)
> >
> > You can't pass a linked list in a control message because a linked
> > list implies pointers. A control message only contains a chunk of
> > data, i.e., 0 or more bytes (like a packet). So the thing to do in
> > this instance is to copy your linked list into a (variable sized)
> > array and put that array into the payload of the control message.
>
> or use a shower of individual 'discovery' messages.
> it doesn't happen that often..
Yeah. Sounds good.
--
Benno Rice "No, no. We're *sweet* and
XNFP Aries Dark Subculture- *innocent* evil bastards."
friendly Internet Geek
benno@netizen.com.au "Defend your joy"
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