Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755633Ab1CMRGh (ORCPT ); Sun, 13 Mar 2011 13:06:37 -0400 Received: from one.firstfloor.org ([213.235.205.2]:58115 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755367Ab1CMRGg (ORCPT ); Sun, 13 Mar 2011 13:06:36 -0400 Date: Sun, 13 Mar 2011 18:06:32 +0100 From: Andi Kleen To: Thomas Gleixner Cc: Dave Jones , x86@kernel.org, Andi Kleen , Arjan van de Ven , Linux Kernel Subject: Re: RFC: Bogus setting of CONSTANT TSC ? Message-ID: <20110313170632.GK2499@one.firstfloor.org> References: <20110311212418.GA14784@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 824 Lines: 18 > This was initially introduced with commit 39b3a7 ([PATCH] i386/x86-64: > Generalize X86_FEATURE_CONSTANT_TSC flag), though the changelog is > utterly useless. Andi ?? Only Nehalem and beyond set the 8000_0007 flag, but Intel has had a constant TSC since Yonah. That is what this logic implements. However on Nehalem and beyond if the 8000_0007 is clear the BIOS wants to tell us that it knows the system doesn't have a synchronized TSC. This is currently still broken, but the timer watchdog usually catches it later. It only affects a few relatively obscure systems. -Andi -- 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/