From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www.linutronix.de ([62.245.132.108]:58507 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757876AbcEFJzM (ORCPT ); Fri, 6 May 2016 05:55:12 -0400 Date: Fri, 6 May 2016 11:53:25 +0200 (CEST) From: Thomas Gleixner To: Chen Yu cc: x86@kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , "H. Peter Anvin" , Bin Gao , Len Brown , "Rafael J. Wysocki" , "3 . 14+ # 3 . 14+" Subject: Re: [PATCH] x86, tsc: Fix tsc ratio calibration to avoid broken mdelay In-Reply-To: Message-ID: References: <1462505619-5516-1-git-send-email-yu.c.chen@intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: stable-owner@vger.kernel.org List-ID: On Fri, 6 May 2016, Thomas Gleixner wrote: > On Fri, 6 May 2016, yu.c.chen@intel.com wrote: > > From: Chen Yu > > > > Currently we fetch the tsc radio by: > > ratio = (lo >> 8) & 0x1f; > > thus get bit8~bit12 of the MSR_PLATFORM_INFO, however according > > to Intel 64 and IA-32 Architectures Software Developer Manual 35.5, > > the ratio bit should be bit8~bit15, otherwise we might get incorrect > > tsc ratio and cause system hang later(mdelay corrupted). > > The resulting issue is that both TSC frequency, which is used for udelay, and > the lapic timer frequency are wrong. mdelay is just the visible damage caused > by that. Aside of that: > Cc: 3.14+ # 3.14+ Please use: Fixes: commit '....' next time, which identifies the kernel version to which this needs to be backported and gives a reference to the commit which caused the issue. Thanks, tglx