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From: pete@ohm.york.ac.uk (-Pete French.)
Newsgroups: comp.os.minix
Subject: Re: Lance (ethernet) driver
Message-ID: <1991Jun13.101205.5127@ohm.york.ac.uk>
Date: 13 Jun 91 10:12:05 GMT
References: <91162.122856RON@psuvm.psu.edu>
Organization: Electronics Department, University of York, UK
Lines: 31

in article <91162.122856RON@psuvm.psu.edu>, RON@psuvm.psu.edu (Ron McCarty) says:
> 
> In article <3133@redstar.dcs.qmw.ac.uk>, zawada@dcs.qmw.ac.uk (Simpson) says:
> 
> 
> The Lance chip is also at the heart of the DEC DEMCA ethernet card which is
> used to connect PS2s to an ethernet. I have received the literature on the
> Lance chip (it is made by Advanced Micro Devices), and hope to convert
> the Minix ethernet driver this summer when I get to it.

Ive written LANCE device drivers before now and they are not too hard - except
that there are certain things you have to do which arent mentioned in the
documentation. The most important of these is that when you are freeing
the ring buffers you must do so in REVERSE order (anticlockwise round the ring).

This also applies when marking the ring buffers as containing a packet for
transmission - do it in reverse order. The reason behind this is obvious if
you think about it, but if not you get a driver which woirkes 80% of the time
but falls over occasionally for no apparent reason. These are the hardest
bugs to fix.

Have fun....

-bat.

PS: My code was written in OCCAM and so is not really portable.
-- 
-Pete French. (the -bat. )         /  "Two wrongs don't make a right,
Adaptive Systems Engineering      /    - but three lefts do !"

"Look here, a Brit who has obviously been driving in California!"