From: Arnd Bergmann <arnd@arndb.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
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
Subject: Re: x86: Is 'volatile' necessary for readb/writeb and friends?
Date: Fri, 4 Dec 2009 17:00:39 +0100 [thread overview]
Message-ID: <200912041700.39564.arnd@arndb.de> (raw)
In-Reply-To: <8B1FEF0C-5D71-4D64-ADC3-1EE60F50779F@kernel.crashing.org>
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 <><
next prev parent reply other threads:[~2009-12-04 16:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-04 9:21 x86: Is 'volatile' necessary for readb/writeb and friends? Ahmed S. Darwish
2009-12-04 14:39 ` Segher Boessenkool
2009-12-04 16:00 ` Arnd Bergmann [this message]
2009-12-04 17:30 ` H. Peter Anvin
2009-12-04 19:54 ` Segher Boessenkool
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