From: Arnd Bergmann <arnd@arndb.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: x86: Is 'volatile' necessary for readb/writeb and friends?
Date: Fri, 4 Dec 2009 17:00:39 +0100
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Cc: "Ahmed S. Darwish" <darwish.07@gmail.com>, x86@kernel.org,
       Rusty Russell <rusty@rustcorp.com.au>, Ingo Molnar <mingo@redhat.com>,
       "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
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On Friday 04 December 2009, Segher Boessenkool wrote:
> If you want to get all language-lawyery, if the object pointed to by
> "addr" is volatile, the volatile here is needed: accessing volatile
> objects via a not volatile-qualified lvalue is undefined.  But since
> this is GCC-specific code anyway, do you care?  :-)

I think the real reason for having it is to avoid a warning when
device drivers pass volatile objects. Not sure if that's a good
thing or if we should better actually warn about it.

	Arnd <><
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