Messages in this thread | | | Date | Mon, 8 Oct 2012 15:59:39 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] make CONFIG_EXPERIMENTAL invisible and default |
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On Mon, Oct 08, 2012 at 03:40:57PM -0700, Kees Cook wrote: > On Mon, Oct 8, 2012 at 3:37 PM, Kees Cook <keescook@chromium.org> wrote: > > On Mon, Oct 8, 2012 at 3:29 PM, Paul E. McKenney > > <paulmck@linux.vnet.ibm.com> wrote: > >> On Mon, Oct 08, 2012 at 03:07:24PM -0700, Kees Cook wrote: > >>> On Sun, Oct 7, 2012 at 6:04 PM, Paul E. McKenney > >>> <paulmck@linux.vnet.ibm.com> wrote: > >>> > 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? > >>> > >>> I think we should avoid any global configs that disable things. We'll > >>> just end up in the same place with distros again. > >> > >> So you believe that we should taint the kernel or splat on boot to > >> warn distros off of features that might not be ready for 100 million > >> users? Or do you have some other approach in mind? > > > > Personally, I think taint+printk seems like the right way to go. > > Actually, I think printk is sufficient. I don't want kernel taint to > become the new CONFIG_EXPERIMENTAL. :)
OK, I'll bite...
Why would kernel taint be more likely to become the new CONFIG_EXPERIMENTAL than printk() would?
Thanx, Paul
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