Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756889AbYGYNso (ORCPT ); Fri, 25 Jul 2008 09:48:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752678AbYGYNsg (ORCPT ); Fri, 25 Jul 2008 09:48:36 -0400 Received: from nf-out-0910.google.com ([64.233.182.190]:36011 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750934AbYGYNsf (ORCPT ); Fri, 25 Jul 2008 09:48:35 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=o500tzHsmDS7qnhzV8R0AA0ODYmKN0kM2UBRHle5ACisKuABR0+j1624v58XOcXuaf BQN76LBpeo1hBLyCuDk8OO8g5Ng6FRkiYtocQ4j45Z/kI767nRHKY1Zva2zLflMRUfmk a5SESDOLKwmHHk1CS/D5teYC3KySxrEf5JXlo= Date: Fri, 25 Jul 2008 17:48:31 +0400 From: Cyrill Gorcunov To: Martin Wilck Cc: Thomas Gleixner , "linux-kernel@vger.kernel.org" , "H. Peter Anvin" , "Wichert, Gerhard" , "Maciej W. Rozycki" Subject: Re: [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe (take 2) Message-ID: <20080725134831.GB28466@lenovo> References: <20080724120512.GA21804@lenovo> <488889B6.9070707@fujitsu-siemens.com> <20080724143151.GA32422@lenovo> <20080724150116.GC32422@lenovo> <48889C14.4070408@fujitsu-siemens.com> <4889968E.6020000@fujitsu-siemens.com> <20080725100844.GA16698@lenovo> <4889C723.7050402@fujitsu-siemens.com> <20080725125950.GA28466@lenovo> <4889D767.5050709@fujitsu-siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4889D767.5050709@fujitsu-siemens.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1314 Lines: 31 [Martin Wilck - Fri, Jul 25, 2008 at 03:38:47PM +0200] > I wrote: > >> I have to say that my simplified patch failed to do the calibration >> correctly on our test system (the original patch worked well). Please >> stay tuned, we are investigating this currently. > > Please forget that. It was observed on an old "enterprise" kernel with > which we are currently testing the backported patch with, and it was due > to the fact that the initial counter value on that kernel was divided by > APIC_DIVISOR (=16). The resulting initial counter value was too low in a > "SMI flood" case, the counter could overlap. APIC_DIVISOR is no longer > used in the current kernel. > > Martin > > -- Martin, if I understood you right - this means your patch is not needed? Actually on 64bit mode APIC_DIVISOR is a bit hidden in __setup_APIC_LVTT - you may see it as APIC_TDR_DIV_16 while setting up divisor register. I was proposing patch for that but it leaded to potetntial overflow (thanks Ingo for catching) so we leave it as is. Maybe I miss something? - Cyrill - -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/