From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754300Ab3JXJIj (ORCPT ); Thu, 24 Oct 2013 05:08:39 -0400 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:34648 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396Ab3JXJIh (ORCPT ); Thu, 24 Oct 2013 05:08:37 -0400 X-Originating-IP: 77.221.165.98 Date: Thu, 24 Oct 2013 10:08:30 +0100 From: Josh Triplett To: Richard Weinberger Cc: "linux-doc@vger.kernel.org" , LKML , Linus Torvalds , Rob Landley , Tao Ma , Andrew Morton , Greg Kroah-Hartman , "H. Peter Anvin" Subject: Re: [PATCH] Documentation/ABI: Document the non-ABI status of Kconfig and symbols Message-ID: <20131024090825.GA3217@leaf> References: <20131024084104.GA2861@leaf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 On Thu, Oct 24, 2013 at 10:57:11AM +0200, Richard Weinberger wrote: > On Thu, Oct 24, 2013 at 10:41 AM, Josh Triplett wrote: > > Discussion at Kernel Summit made it clear that the presence or absence > > of specific Kconfig symbols are not considered ABI, and that no > > userspace (or bootloader, etc) should rely on them. > > > > In addition, kernel-internal symbols are well established as non-ABI, > > per Documentation/stable_api_nonsense.txt. > > > > Document both of these in Documentation/ABI/README, in a new section for > > notable bits of non-ABI. > > > > Signed-off-by: Josh Triplett > > --- > > Documentation/ABI/README | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/Documentation/ABI/README b/Documentation/ABI/README > > index 1006982..1fafc4b 100644 > > --- a/Documentation/ABI/README > > +++ b/Documentation/ABI/README > > @@ -72,3 +72,16 @@ kernel tree without going through the obsolete state first. > > > > It's up to the developer to place their interfaces in the category they > > wish for it to start out in. > > + > > + > > +Notable bits of non-ABI, which should not under any circumstances be considered > > +stable: > > + > > +- Kconfig. Userspace should not rely on the presence or absence of any > > + particular Kconfig symbol, in /proc/config.gz, in the copy of .config > > + commonly installed to /boot, or in any invocation of the kernel build > > + process. > > + > > +- Kernel-internal symbols. Do not rely on the presence, absence, location, or > > + type of any kernel symbol, either in System.map files or the kernel binary > > + itself. See Documentation/stable_api_nonsense.txt. > > And what about the kernel make "interface", is it considered also as non-ABI? > > E.g. > Before ffee0de (x86: Default to ARCH=x86 to avoid overriding CONFIG_64BIT) > "make defconfig ARCH=x86" produced a i386 defconfig. Now it produces a > x86_64 defconfig. > I'm sure some build scripted failed badly. I seriously considered including that, but I could imagine that some parts of that interface might be considered more stable than others (the names of targets, for instance), and I wanted to stick to completely uncontroversial items. If there's consensus that part or all of the invocation of "make" to build the kernel is non-ABI, we can easily enough add that to the non-ABI list, but let's start with Kconfig and symbols. - Josh Triplett