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From: keith@uport.UUCP (Keith Hankin)
Newsgroups: comp.unix.microport,comp.sys.att,comp.databases
Subject: Re: (386) Unix (In)compatibilities Summary
Summary: Writing modular device drivers can be tricky
Message-ID: <448@uport.UUCP>
Date: 31 Aug 88 23:50:11 GMT
References: <1988Aug26.220549.14910@gpu.utcs.toronto.edu> <1061@apt.UUCP> <1988Aug30.232449.15486@gpu.utcs.toronto.edu>
Reply-To: keith@uport.UUCP (Keith Hankin)
Distribution: comp
Organization: Microport Systems, Scotts Valley, CA
Lines: 32

In article <1988Aug30.232449.15486@gpu.utcs.toronto.edu> woods@gpu.utcs.Toronto.EDU (Greg Woods) writes:
|Tricky things, those device drivers!
|
|One note that especially caught my eye today was something about
|Microport mucking with the internal interfaces of device drivers and the
|kernel.  Microport's drivers won't link with the ISC kernel and
|vice-versa, so it was implied.
|
|Sounds like someone is trying to throw their weight around.  This is
|just going to discourage people from supporting both systems.  Why I
|sure wouldn't want to maintain drivers for two VERY similar but
|definitely different systems!
|
|						Greg Woods
|
|UUCP: utgpu!woods, utgpu!{ontmoh, ontmoh!ixpierre}!woods
|VOICE: (416) 242-7572 [h]		LOCATION: Toronto, Ontario, Canada

Yes, writing modular device drivers can be tricky.  Problems do crop up
including multiply defined variable names, externals that are defined in
one place and used elsewhere, etc.  These problems are not by design 
(or at least not here at Microport) but rather by oversight during the
original development of the driver.

We have been working to eliminate such interdependencies through renaming,
puting variables used in 2 places into the space.c and documenting them,
etc...  Whatever is necessary to make the modules independent.  However
it is not always easy.

-- 
Keith Hankin	keith@uport
Microport Systems