From: Andi Kleen <andi@firstfloor.org>
To: Stephan Diestelhorst <langer_mann@web.de>
Cc: Ingo Molnar <mingo@elte.hu>,
davej@codemonkey.org.uk, cpufreq@lists.linux.org.uk,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX
Date: 10 Mar 2008 17:46:37 +0100 [thread overview]
Message-ID: <87iqzu8r2q.fsf@basil.nowhere.org> (raw)
In-Reply-To: <200803101605.42251.langer_mann@web.de>
Stephan Diestelhorst <langer_mann@web.de> writes:
>
> New attempt with full clobbers, note that I deliberatly did not change
> the order of the output registers. Real output operands still preceede
> outputs used for potential clobbering.
>
> I'm not too sure about the EBP push/pop frame, but as folks pointed
> out already, we should not trust the SMI code too much.
Be careful -- older gcc versions tend to abort for inline asm
that clobbers too many registers. Especially when the register
is already used (like ebp in a frame pointer enabled kernel)
Make sure it at least works on the oldest supported gcc version
(gcc 3.2) and with frame pointer on.
For asms with so many clobbers explicit push/pop is usually safer.
-Andi
next prev parent reply other threads:[~2008-03-10 16:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-05 14:59 [PATCH 1/1] Speedfreq-SMI call clobbers ECX Stephan Diestelhorst
2008-03-05 15:35 ` Ingo Molnar
2008-03-05 16:02 ` H. Peter Anvin
2008-03-06 8:38 ` Stephan Diestelhorst
2008-03-06 8:51 ` Stephan Diestelhorst
2008-03-06 10:56 ` Ingo Molnar
2008-03-10 15:05 ` Stephan Diestelhorst
2008-03-10 16:46 ` Andi Kleen [this message]
2008-03-10 21:26 ` Stephan Diestelhorst
2008-03-10 21:51 ` Andi Kleen
2008-03-10 23:14 ` Stephan Diestelhorst
2008-03-11 9:39 ` Ingo Molnar
2008-03-12 15:04 ` Stephan Diestelhorst
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