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Date:      Mon, 21 Jun 1999 10:37:27 +0100 (BST)
From:      Doug Rabson <dfr@nlsystems.com>
To:        Peter Wemm <peter@netplex.com.au>
Cc:        cvs-committers@freebsd.org, cvs-all@freebsd.org
Subject:   Re: cvs commit: src/sys/isa sio.c 
Message-ID:  <Pine.BSF.4.05.9906211035360.80685-100000@herring.nlsystems.com>
In-Reply-To: <19990621071211.988BB75@overcee.netplex.com.au>

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On Mon, 21 Jun 1999, Peter Wemm wrote:

> Doug Rabson wrote:
> > On Sun, 20 Jun 1999, Peter Wemm wrote:
> > 
> > > peter       1999/06/20 06:10:11 PDT
> > > 
> > >   Modified files:
> > >     sys/isa              sio.c 
> > >   Log:
> > >   Use the proper interfaces to find if a device is enabled, don't dig into
> > >   the bus mechanism's private internals!
> > 
> > Well spotted. For future reference, bus_private.h may not be included by
> > any drivers. Any driver which includes this header should be considered
> > broken.
> 
> Well, I wouldn't go quite that far..  Usually this would be the case, the
> whole point of the bus interface system is to avoid structures for this
> sort of thing and diving in severely impairs binary upwards compatability.
> If a driver or bus genuinely *does* need to get to the internals, then
> either the programmer is attacking the problem the wrong way or the public
> interfaces are inadequate.  For actual bus devices, it is not all that
> unlikely that there are weaknesses.

I would rather that people tackle these weaknesses by asking me how to
solve their problem or by suggesting new functionality for the 'approved'
api. I really think its a bad idea for drivers to use bus_private.h at
all.

--
Doug Rabson				Mail:  dfr@nlsystems.com
Nonlinear Systems Ltd.			Phone: +44 181 442 9037




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