Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753278AbYGYPBU (ORCPT ); Fri, 25 Jul 2008 11:01:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750729AbYGYPBK (ORCPT ); Fri, 25 Jul 2008 11:01:10 -0400 Received: from nf-out-0910.google.com ([64.233.182.191]:43729 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750706AbYGYPBJ (ORCPT ); Fri, 25 Jul 2008 11:01:09 -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=dsNDVawwR1E5alpuRN/af2HVEZxsyv8JSKFPkT1wUUjn9D9qtDJ51ck7SBzDoiB+CV 8ixOwXvogrHmjIo8GHUp9g4q2y/Uzg2/AUsu8DGLGXJuV9/opSDUDd6f+ISt0E+GvV2H dhVkF5OfvWPRZ16xGUObZ4ClCAXMJyM7Jzbu8= Date: Fri, 25 Jul 2008 19:01:04 +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 3) Message-ID: <20080725150104.GD28466@lenovo> References: <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> <20080725134831.GB28466@lenovo> <4889DCA4.4010800@fujitsu-siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4889DCA4.4010800@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: 1527 Lines: 38 [Martin Wilck - Fri, Jul 25, 2008 at 04:01:08PM +0200] > Cyrill Gorcunov wrote: > >> Martin, if I understood you right - this means your patch is not >> needed? > > The patch would still be needed. Just the reported failure of my > simplified patch on the old kernel would not have occurred in the > current kernel. IOW, the patch is fine for the current kernel, but not > for the old one. > >> 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? > > The problem was not that the divisor 16 was used for the counter speed > (APIC_TDR_DIV_16), but that the old code set the counter start value to > (250000000/16) rather than just 250000000. That means the counter will > underflow earlier. > > I am attaching a "take 3" patch which minimizes the risk of an underflow > by using the maximum possible initial value for the APIC timer. > > Martin > Martin, it seems you forgot to attach the patch :) (since it was continious tense I thought I would see patch in minute but... it was not eventually apeeared :) - 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/