Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754712AbcLOTJI (ORCPT ); Thu, 15 Dec 2016 14:09:08 -0500 Received: from mail.skyhub.de ([78.46.96.112]:44984 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754508AbcLOTJG (ORCPT ); Thu, 15 Dec 2016 14:09:06 -0500 Date: Thu, 15 Dec 2016 20:09:02 +0100 From: Borislav Petkov To: hpa@zytor.com Cc: Linus Torvalds , "Kirill A. Shutemov" , Andrew Morton , the arch/x86 maintainers , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , Andi Kleen , 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: <20161215190902.tdle4uj27xkc3x4i@pd.tnic> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 594 Lines: 20 On Thu, Dec 15, 2016 at 09:52:12AM -0800, hpa@zytor.com wrote: > This really is only worthwhile if it ends up producing better code, > but I doubt it. Nah, the most it does is drops those ifnc lines in there on newer gccs. They will appear only on gcc-4 and earlier and if we're -fPIC and if we're -m32 and if we have enough register pressure to force gcc to use the PIC register It was a good exercise for me to see in detail how would I go about doing a gcc-specific workaround. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.