linux-kernel - Re: [PATCH] x86: do_boot_cpu - add check if we have ESR register

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Date:	Mon, 22 Sep 2008 13:51:48 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Ingo Molnar <mingo@...e.hu>, Yinghai Lu <yhlu.kernel@...il.com>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: do_boot_cpu - add check if we have ESR register

[Cyrill Gorcunov - Mon, Sep 22, 2008 at 01:36:03PM +0400]
| We should touch ESR register if only we have one.
| Check its presence first.
| 
| Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
| CC: Yinghai Lu <yhlu.kernel@...il.com>
| ---
| 
| Index: linux-2.6.git/arch/x86/kernel/smpboot.c
| ===================================================================
| --- linux-2.6.git.orig/arch/x86/kernel/smpboot.c	2008-09-18 19:17:16.000000000 +0400
| +++ linux-2.6.git/arch/x86/kernel/smpboot.c	2008-09-22 13:30:36.000000000 +0400
| @@ -893,8 +893,10 @@ do_rest:
|  		/*
|  		 * Be paranoid about clearing APIC errors.
|  	 	*/
| -		apic_write(APIC_ESR, 0);
| -		apic_read(APIC_ESR);
| +		if (APIC_INTEGRATED(apic_version[phys_apicid])) {
| +			apic_write(APIC_ESR, 0);
| +			apic_read(APIC_ESR);
| +		}
|  	}
|  
|  	/*

Actually it's resend of the patch. On previous attempt
Yinghai was proposed to choose:

> one apic_version or boot_cpu_apic_version could be enough

but I think it should be different patch which does cleaning
up variables usage. So for now I think _this_ patch is enough
since idea is to prevent of touching nonexistant register rather
code cleaning (whci could be done later).

Yinghai?

		- Cyrill -
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