From: "H. Peter Anvin" <hpa@zytor.com>
To: Jan Beulich <jbeulich@novell.com>
Cc: mingo@elte.hu, tglx@linutronix.de, linux-kernel@vger.kernel.org
Subject: Re: [RFC] x86: bitops asm constraint fixes
Date: Fri, 14 Mar 2008 08:51:11 +0100 [thread overview]
Message-ID: <47DA2E6F.5080907@zytor.com> (raw)
In-Reply-To: <47D8FD33.76E4.0078.0@novell.com>
Jan Beulich wrote:
>
> I'd really like understand, though, what the policy of (not) having a
> "memory" clobber in these operations is - currently, this appears to
> be totally inconsistent. Also, many comments of the non-atomic
> functions say those may also be re-ordered - this contradicts the use
> of "asm volatile" in there, which again I'd like to understand.
>
In general, proper "m" constraints are better than "memory" clobbers,
since they give gcc more information. Note that the "m" constraint
doesn't actually have to be *manifest* in the assembly string.
-hpa
next prev parent reply other threads:[~2008-03-14 7:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-13 9:08 [RFC] x86: bitops asm constraint fixes Jan Beulich
2008-03-14 7:51 ` H. Peter Anvin [this message]
2008-03-14 8:09 ` Jan Beulich
2008-03-14 18:56 ` Jeremy Fitzhardinge
2008-03-17 9:08 ` Jan Beulich
2008-03-14 21:07 ` Chuck Ebbert
2008-03-17 9:16 ` Jan Beulich
2008-03-19 13:19 ` H. Peter Anvin
2008-03-21 13:54 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2008-03-27 8:12 Jan Beulich
2008-03-27 8:41 ` Ingo Molnar
2008-04-14 12:53 ` Jan Beulich
2008-03-28 19:55 Jan Beulich
2008-04-14 13:31 Jan Beulich
2008-04-14 16:21 ` Jeremy Fitzhardinge
2008-04-15 7:03 ` Jan Beulich
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