linux-kernel - Re: [PATCH] x86: smpboot - check if we have ESR register in wakeup_secondary

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Date:	Mon, 15 Sep 2008 09:56:55 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yhlu.kernel@...il.com>
Subject: Re: [PATCH] x86: smpboot - check if we have ESR register in
	wakeup_secondary_cpu


* Cyrill Gorcunov <gorcunov@...il.com> wrote:

> We should check if we have ESR register before writting to it.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
> ---
> 
> Please review!
> it seems the same nit in do_boot_cpu - checking now.
> 
> Index: linux-2.6.git/arch/x86/kernel/smpboot.c
> ===================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/smpboot.c	2008-09-14 19:43:03.000000000 +0400
> +++ linux-2.6.git/arch/x86/kernel/smpboot.c	2008-09-14 21:49:36.000000000 +0400
> @@ -598,10 +598,12 @@ wakeup_secondary_cpu(int logical_apicid,
>  	 * Give the other CPU some time to accept the IPI.
>  	 */
>  	udelay(200);
> -	maxlvt = lapic_get_maxlvt();
> -	if (maxlvt > 3)			/* Due to the Pentium erratum 3AP.  */
> -		apic_write(APIC_ESR, 0);
> -	accept_status = (apic_read(APIC_ESR) & 0xEF);
> +	if (APIC_INTEGRATED(apic_version[phys_apicid])) {
> +		maxlvt = lapic_get_maxlvt();
> +		if (maxlvt > 3)			/* Due to the Pentium erratum 3AP.  */
> +			apic_write(APIC_ESR, 0);
> +		accept_status = (apic_read(APIC_ESR) & 0xEF);
> +	}
>  	pr_debug("NMI sent.\n");

hm, is there any non-integrated lapic that has more than 3 lvts? iirc 
lvts were introduced with the integrated lapic.

	Ingo
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