Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933144Ab2JDAMJ (ORCPT ); Wed, 3 Oct 2012 20:12:09 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:50494 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932788Ab2JDAMH (ORCPT ); Wed, 3 Oct 2012 20:12:07 -0400 Date: Wed, 3 Oct 2012 17:11:59 -0700 From: "Paul E. McKenney" To: "Eric W. Biederman" Cc: Kees Cook , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Serge Hallyn , "David S. Miller" , Andrew Morton , Frederic Weisbecker Subject: Re: [PATCH] make CONFIG_EXPERIMENTAL invisible and default Message-ID: <20121004001159.GW2527@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20121002195042.GA16087@www.outflux.net> <20121003132538.GE13192@linux.vnet.ibm.com> <20121003161702.GA22008@kroah.com> <20121003164712.GF2527@linux.vnet.ibm.com> <20121003200314.GR2527@linux.vnet.ibm.com> <87k3v719gg.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k3v719gg.fsf@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12100400-7408-0000-0000-0000090245D2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4317 Lines: 87 On Wed, Oct 03, 2012 at 03:23:27PM -0700, Eric W. Biederman wrote: > "Paul E. McKenney" writes: > > > On Wed, Oct 03, 2012 at 11:43:32AM -0700, Kees Cook wrote: > >> On Wed, Oct 3, 2012 at 9:47 AM, Paul E. McKenney > >> wrote: > >> > On Wed, Oct 03, 2012 at 09:17:02AM -0700, Greg Kroah-Hartman wrote: > >> >> On Wed, Oct 03, 2012 at 06:25:38AM -0700, Paul E. McKenney wrote: > >> >> > On Tue, Oct 02, 2012 at 12:50:42PM -0700, Kees Cook wrote: > >> >> > > This config item has not carried much meaning for a while now and is > >> >> > > almost always enabled by default. As agreed during the Linux kernel > >> >> > > summit, it should be removed. As a first step, remove it from being > >> >> > > listed, and default it to on. Once it has been removed from all > >> >> > > subsystem Kconfigs, it will be dropped entirely. > >> >> > > > >> >> > > CC: Greg KH > >> >> > > CC: "Eric W. Biederman" > >> >> > > CC: Serge Hallyn > >> >> > > CC: "Paul E. McKenney" > >> >> > > CC: Andrew Morton > >> >> > > CC: Frederic Weisbecker > >> >> > > Signed-off-by: Kees Cook > >> >> > > --- > >> >> > > > >> >> > > This is the first of a series of 202 patches removing EXPERIMENTAL from > >> >> > > all the Kconfigs in the tree. Should I send them all to lkml (with all > >> >> > > the associated CCs), or do people want to cherry-pick changes from my > >> >> > > tree? I don't want to needlessly flood the list. > >> >> > > > >> >> > > http://git.kernel.org/?p=linux/kernel/git/kees/linux.git;a=shortlog;h=refs/heads/experimental > >> >> > > > >> >> > > I figure this patch can stand alone to at least make EXPERIMENTAL go > >> >> > > away from the menus, and give us a taste of what the removal would do > >> >> > > to builds. > >> >> > > >> >> > OK, I will bite... How should I flag an option that is initially only > >> >> > intended for those willing to take some level of risk? > >> >> > >> >> In the text say "You really don't want to enable this option, use at > >> >> your own risk!" Or something like that :) > >> > > >> > OK, so the only real hope for experimental features is to refrain from > >> > creating a config option for them, so that people wishing to use them > >> > must modify the code? Or is the philosophy that we keep things out of > >> > tree until we are comfortable with distros turning them on? > >> > >> I would expect a simple addition of "this is dangerous/buggy" to the > >> description and "default n" is likely the way to go for that kind of > >> thing. I think the history of CONFIG_EXPERIMENTAL has proven there > >> isn't a sensible way to create a global flag for this kind of thing. > >> To paraphrase Serge: my experimental options are not your experimental > >> options. > > > > That has not proven sufficient for me in the past, RCU_FAST_NO_HZ > > being a case in point. > > One option that does work is to add a negative Kconfig dependency such > as "depends on EXT4 = n". Where what you depend on is something that > distros want. > > Where I had a legitimate reason to do that with the user namespace > (aka the code that had not been converted did not compile and was not > safe to use) it worked very well in keeping distros from getting ahead > of them selves, and likewise it works very well for ensuring it got > itself removed as ultimately you want to the two kconfig options to work > together. Cute! ;-) > >> For example, some of the things that already had the experimental > >> config removed, they left the "(EXPERIMENTAL)" in their config title. > > > > Or I could just make it splat at boot time. ;-) > > Yes. Treating a truly experimental feature like a deprecated feature > and complaining to the world also seems reasonable, and it seems like > something that would ultimatley get removed as well. Either removed or fixed, as the case may be. 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/