From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755730Ab2IQK65 (ORCPT ); Mon, 17 Sep 2012 06:58:57 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:35712 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755642Ab2IQK64 convert rfc822-to-8bit (ORCPT ); Mon, 17 Sep 2012 06:58:56 -0400 Message-Id: <50571E8B020000780009BBB2@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Mon, 17 Sep 2012 11:58:51 +0100 From: "Jan Beulich" To: "Ingo Molnar" Cc: , , , Subject: Re: [tip:x86/asm] x86: Prefer TZCNT over BFS References: <504DEA1B020000780009A277@nat28.tlf.novell.com> <5056F04B020000780009BAF9@nat28.tlf.novell.com> <20120917100046.GA32463@gmail.com> In-Reply-To: <20120917100046.GA32463@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 17.09.12 at 12:00, Ingo Molnar wrote: > Linus's suggestion is to introduce CONFIG_X86_TZCNT as an add-on > patch that cleans up and documents what this is all about. It wasn't just this he complained about. Plus I don't think the suggested name fits the current scheme - it would imply the instruction to be available when set, yet that's explicitly _not_ a requirement. So X86_USE_TZCNT would seem a better fit to me. > Would you be willing to do such a patch? If that was the only change needed, yes (hesitantly, as I personally don't think introducing Kconfig options that have only a single usage point is really useful). But the complaint regarding this also getting enabled for old CPUs (which in my understanding is the purpose of the GENERIC options) is something that I wouldn't be willing to address (unless I'm told these two options have another purpose), and thus I would expect the resulting patch to still get vetoed by Linus (which in essence means it would be wasted time to try to address the other complaint). Jan