From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753397AbbJSIQV (ORCPT ); Mon, 19 Oct 2015 04:16:21 -0400 Received: from mx2.suse.de ([195.135.220.15]:53278 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753350AbbJSIQR (ORCPT ); Mon, 19 Oct 2015 04:16:17 -0400 Date: Mon, 19 Oct 2015 10:16:10 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: x86-ml , Peter Zijlstra , Steven Rostedt , lkml Subject: Re: [RFC PATCH] x86: Kill notsc Message-ID: <20151019081610.GB20028@pd.tnic> References: <20151018142007.GA11294@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 18, 2015 at 09:47:21PM -0700, Andy Lutomirski wrote: > I'm a bit confused. Is it currently the case that, if you boot a > normal kernel on a TSC-less machine without notsc, it fails? No, it shouldn't fail because we're checking CPUID flags. The point of this patch is purely cleaning up stuff and getting rid of all the notsc/tsc_disabled logic. What is more tempting, however, is getting rid of the static key in native_sched_clock. It is almost pointless complexity and we don't really need it. AFAIK, only some early 486s and 586s don't have TSC and they can disable CONFIG_X86_TSC. Which they do, actually, if you choose M486 or M586 in Kconfig. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --