Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753060Ab2JCTzt (ORCPT ); Wed, 3 Oct 2012 15:55:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14259 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752049Ab2JCTzr (ORCPT ); Wed, 3 Oct 2012 15:55:47 -0400 Date: Wed, 3 Oct 2012 15:36:53 -0400 From: Dave Jones To: Frederic Weisbecker Cc: Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , linux-kernel@vger.kernel.org, "Eric W. Biederman" , Serge Hallyn , "David S. Miller" , Andrew Morton Subject: Re: [PATCH] make CONFIG_EXPERIMENTAL invisible and default Message-ID: <20121003193653.GB30477@redhat.com> Mail-Followup-To: Dave Jones , Frederic Weisbecker , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , linux-kernel@vger.kernel.org, "Eric W. Biederman" , Serge Hallyn , "David S. Miller" , Andrew Morton References: <20121002195042.GA16087@www.outflux.net> <20121003132538.GE13192@linux.vnet.ibm.com> <20121003161702.GA22008@kroah.com> <20121003164712.GF2527@linux.vnet.ibm.com> <20121003172142.GA5061@kroah.com> <20121003174606.GB637@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121003174606.GB637@somewhere> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2024 Lines: 40 On Wed, Oct 03, 2012 at 07:46:18PM +0200, Frederic Weisbecker wrote: > > it in the kernel tree, unless we wanted people to use the option? > > A solution could be to add that option under CONFIG_DEBUG_KERNEL and specify > that it must only be enabled by developers for specific reasons (overhead, > security). CONFIG_PROVE_LOCKING falls into that category, right? > > We have CONFIG_RCU_USER_QS that is a specific case. It's an intermediate state > before we implement a true CONFIG_NO_HZ_FULL. But the option is useless on its > own for users. Worse, it introduces a real overhead. OTOH we want it to be upstream > to make the development of full tickless feature more incremental. > > Perhaps we should put that under CONFIG_DEBUG_KERNEL. Overloading an existing config option for something unrelated seems unpleasant to me. It will only take a few people to start doing this, before it turns into a landslide where everyone ends up with DEBUG_KERNEL set. And what of people who already have DEBUG_KERNEL set ? Just state what you wrote above in the kconfig. Currently, RCU_USER_QS says nothing about the fact that it's work in progress. The missing part that I don't have an answer for however, is what happens when you deem this production ready? Distro maintainers won't notice the kconfig text changing. But perhaps that's a good thing, and will lead to things only being enabled when people explicitly ask for them in distros. Alternatively, if you really do want to go the path of a new config option, perhaps CONFIG_NOT_DISTRO_READY would spell things out more clearly. EXPERIMENTAL is such a wasteland it would take too much manpower to audit every case, and update accordingly, but scorching the earth and starting afresh might be feasible. Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/