From owner-freebsd-net  Sat Nov 17 14:16:16 2001
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To: Julian Elischer <julian@elischer.org>
Cc: Peter Wemm <peter@wemm.org>,
	Julian Elischer <julian@vicor-nb.com>, current@FreeBSD.ORG,
	net@FreeBSD.ORG, wollman@FreeBSD.ORG
Subject: Re: re-entrancy and the IP stack. 
In-Reply-To: Message from Julian Elischer <julian@elischer.org> 
   of "Fri, 16 Nov 2001 16:13:41 PST." <Pine.BSF.4.21.0111161611270.6632-100000@InterJet.elischer.org> 
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Date: Sat, 17 Nov 2001 14:17:32 -0800
From: "George V. Neville-Neil" <gnn@neville-neil.com>
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X-Loop: FreeBSD.org

I recommend you all look at The Click Modular router

http://www.pdos.lcs.mit.edu/click/

which is a step in the right direction.

Of course given the current architecture it may be very hard
to adapt it to this kind of model.

I led/worked on a project at Wind River Systems to do a multi-instance
stack based off of the 4.4 BSD lite code.   I can tell you that without
quite a bit of rearchitecting what you get is always a hack.

There are (were?) over 100 global variables in the 4.4BSD lite code.  I've
not counted on 4.4 or -CURRENT so I can't say.  There are also the issues
of the locks though I suspect in -CURRENT (since the kernel is MP) you
have handled these in some way.

An extensible, multi-threaded TCP/IP would NOT look like the 4.4BSD-Lite code.

Is this a goal of FreeBSD now?  I am working on some things to make this 
possible
but it is independent of FreeBSD and very very early days as yet.

Later,
George



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