linux-kernel - Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX

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Message-ID: <20080305153520.GB19300@elte.hu>
Date:	Wed, 5 Mar 2008 16:35:20 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Stephan Diestelhorst <langer_mann@....de>
Cc:	davej@...emonkey.org.uk, cpufreq@...ts.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX


* Stephan Diestelhorst <langer_mann@....de> wrote:

> @@ -184,7 +184,7 @@ static void speedstep_set_state (unsigne
>  		__asm__ __volatile__(
>  			"movl $0, %%edi\n"
>  			"out %%al, (%%dx)\n"
> -			: "=b" (new_state), "=D" (result)
> +			: "=b" (new_state), "=D" (result), "=c" (ecx_clobber)
>  			: "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
>  			);

stupid suggestion: why not do a pusha/popa around those instructions, to 
make sure everything is restored? This isnt a fastpath and being 
conservative about SMI side-effects cannot hurt ...

	Ingo
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