From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756111Ab0JODED (ORCPT ); Thu, 14 Oct 2010 23:04:03 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:36536 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755644Ab0JODEB (ORCPT ); Thu, 14 Oct 2010 23:04:01 -0400 Date: Fri, 15 Oct 2010 05:03:36 +0200 From: Ingo Molnar To: "H. Peter Anvin" Cc: Andrew Morton , Pekka Enberg , David Rientjes , Ingo Molnar , Thomas Gleixner , Casey Dahlin , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [patch] x86: allow ZONE_DMA to be configurable Message-ID: <20101015030336.GB9640@elte.hu> References: <4CB688F4.9040706@zytor.com> <4CB7240E.9000905@zytor.com> <4CB7418C.7010505@zytor.com> <20101014183448.GA3187@elte.hu> <20101014123511.d628f873.akpm@linux-foundation.org> <1bdcb8fa-d858-4a79-ae28-de8c94d13f5f@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1bdcb8fa-d858-4a79-ae28-de8c94d13f5f@email.android.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * H. Peter Anvin wrote: > I don't like the CONFIG_EXPERT prefix, just because it makes it hard > to move things into and out of this rubric, and that's bad... Hm, i'm not sure i agree. > (consider: "oh, that would mean this *huge* patch) ... If config options are present in many places in the source that's an independent problem already. Typically kconfig variables are used in a few places and any rename patch makes it clear in all those places what happened: either a config variable became obscure (moved into CONFIG_EXPERT's scope), *or* a config variable became much less obscure (moved out of that scope) - both important pieces of information, which i dont mind to see happen in every place that gets affected. Put differently: if we have a CONFIG_EXPERT_ kconfig variable in so many places in the kernel that it creates a huge patch then we have some other kind of problem: it either should not be an expert option (it's too common or too important), or it should not be an option at all (it's a perpetual build failure risk). Also, historically we have not been moving kconfig variables in and out of CONFIG_EMBEDDED all that often for this to be an issue in the future. > [...] not to mention that what is CONFIG_EXPERT on one platform may > not be for another! [...] Dunno, that i'd consider more of a bug. If an architecture absolutely needs to configure in or out a kernel feature then it should not be under CONFIG_EXPERT on other architectures either: it only sets us up for cross-arch build failures if say the CONFIG_EXPERT dependency is present on x86. Or, if an architecture still wants it that way, it better be explicitly aware that it's configuring in a little-tested kconfig switch of the kerenl. I.e. something being an 'expert option' is synonymous with obscurity and potential weirdness on at least one arch - which i dont see as inherently wrong to be visible (via the name) on other architectures either. Thanks, Ingo