Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752928Ab2JHBE4 (ORCPT ); Sun, 7 Oct 2012 21:04:56 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:48799 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355Ab2JHBEy (ORCPT ); Sun, 7 Oct 2012 21:04:54 -0400 Date: Sun, 7 Oct 2012 18:04:11 -0700 From: "Paul E. McKenney" To: Dave Jones , Dave Airlie , Frederic Weisbecker , Matthew Garrett , Kees Cook , Greg Kroah-Hartman , 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: <20121008010410.GL2485@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20121003200314.GR2527@linux.vnet.ibm.com> <20121004015539.GA19958@srcf.ucam.org> <20121004143150.GA2464@linux.vnet.ibm.com> <20121005164642.GA10711@linux.vnet.ibm.com> <20121007014447.GB2485@linux.vnet.ibm.com> <20121007163029.GG2485@linux.vnet.ibm.com> <20121007201854.GA6628@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121007201854.GA6628@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12100801-7408-0000-0000-0000091AE80D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2448 Lines: 50 On Sun, Oct 07, 2012 at 04:18:54PM -0400, Dave Jones wrote: > On Sun, Oct 07, 2012 at 09:30:29AM -0700, Paul E. McKenney wrote: > > > > I think Kconfig is mostly what distro would like to use the thing is > > > the Kconfig text needs to be there upfront when its merged, not two > > > months later, since then it too late for a distro to notice. > > > > > > I'd bet most distros would read the warnings, but in a lot of cases > > > the warning don't exist until its too late. > > > > In the case of CONFIG_RCU_USER_QS you are quite right, the warning > > should have been there from the beginning and was not. I suppose you > > could argue that the warning was not sufficiently harsh in the case of > > CONFIG_RCU_FAST_NO_HZ, but either way it did get ignored: > > Maybe if we had a universally agreed upon tag for kconfig, like > "distro recommendation: N" that would make things obvious, and also allow > those of us unfortunate enough to maintain distro kernels to have something > to easily grep for. This would also catch the case when you eventually (hopefully) > flip from an N to a Y. > > There will likely still be some distros that will decide they know better > (and I'm pretty sure eventually I'll find reason to do so myself), but it at least > gives the feature maintainer the "I told you so" clause. > > Something we do quite often for our in-development kernels is enable something > that's shiny, new and unproven, and then when we branch for a release, we turn > it back off. It would be great if a lot of this kind of thing could be more automated. One approach would be to have CONFIG_DISTRO, so that experimental features could use "depends on !DISTRO", but also to have multiple "BLEEDING" symbols. For example, given a CONFIG_DISTRO_BLEEDING_HPC and CONFIG_DISTRO_BLEEDING_RT, CONFIG_RCU_USER_QS might eventually use the following clause: depends on !DISTRO || DISTRO_BLEEDING_HPC || DISTRO_BLEEDING_RT A normal distro would define DISTRO, a distro looking to provide bleeding-edge HPC or real-time features would also define DISTRO_BLEEDING_HPC or DISTRO_BLEEDING_RT, respectively. Does that make sense, or am I being overly naive? Thanx, Paul -- 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/