Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756731AbcLOWQx (ORCPT ); Thu, 15 Dec 2016 17:16:53 -0500 Received: from mga06.intel.com ([134.134.136.31]:3243 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756634AbcLOWQv (ORCPT ); Thu, 15 Dec 2016 17:16:51 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,353,1477983600"; d="scan'208";a="42977593" Date: Thu, 15 Dec 2016 11:20:17 -0800 From: Andi Kleen To: Borislav Petkov Cc: hpa@zytor.com, Linus Torvalds , "Kirill A. Shutemov" , Andrew Morton , the arch/x86 maintainers , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , Dave Hansen , Andy Lutomirski , "linux-arch@vger.kernel.org" , linux-mm , Linux Kernel Mailing List Subject: Re: [RFC, PATCHv1 15/28] x86: detect 5-level paging support Message-ID: <20161215192017.GP8388@tassilo.jf.intel.com> References: <20161208162150.148763-1-kirill.shutemov@linux.intel.com> <20161208162150.148763-17-kirill.shutemov@linux.intel.com> <20161208200505.c6xiy56oufg6d24m@pd.tnic> <20161208202013.uutsny6avn5gimwq@pd.tnic> <20161215143944.ruxr6r3b2atg4tnf@pd.tnic> <20161215190902.tdle4uj27xkc3x4i@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161215190902.tdle4uj27xkc3x4i@pd.tnic> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 175 Lines: 6 The code is not calling CPUID in any performance critical path, only at initialization. So any discussion about saving a few instructions is a complete waste of time. -Andi