From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755690Ab3A0EBJ (ORCPT ); Sat, 26 Jan 2013 23:01:09 -0500 Received: from rhlx01.hs-esslingen.de ([129.143.116.10]:42822 "EHLO rhlx01.hs-esslingen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753259Ab3A0EBG (ORCPT ); Sat, 26 Jan 2013 23:01:06 -0500 Date: Sun, 27 Jan 2013 05:01:04 +0100 From: Andreas Mohr To: Alexander Holler Cc: linux-kernel@vger.kernel.org, Linus Torvalds , Russell King , Thomas Gleixner , Ingo Molnar , Greg Kroah-Hartman , Andrew Morton , Dick Streefland Subject: Re: [PATCH 0/3] Include kernel config by default Message-ID: <20130127040104.GA5422@rhlx01.hs-esslingen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1359207268-9340-1-git-send-email-holler@ahsoftware.de> X-Priority: none 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 Hi, [CC'd extract-ikconfig creator] > I've seen too many systems where the config to build the used kernel got > lost and people were unable to diagnose problems or to rebuild a modified > or updated kernel. It's a subject which worries me since several years. I'm strongly in favour of such a change. The actual config is simply very important for traceability. In a recent case of mine I simply built the kernel on an external HDD and did not copy the config file on deployment (e.g. to /boot). With that kernel build tree then unavailable, I then realized that this kernel fortunately did have IKCONFIG_PROC enabled, thus configs.ko was available for (re-)use. However an argument could be made that the default setting should be the bare-minimum needed to provide this information source in emergency cases (i.e., a manual run of scripts/extract-ikconfig would be in order and easily acceptable). $ ls -l kernel/configs.ko -rw-r--r-- 1 root root 35788 Jan 25 18:43 kernel/configs.ko IMHO more than 32kB for the proc/config.gz module arguably is quite a bit of code for it to painlessly be enabled by default given availability of other methods of retrieval. However, now that I think of it ISTR that using extract-ikconfig on my bzImage did NOT work yet loading configs.ko of the same install successfully provided a /proc/config.gz. Huh?? If this is the case, then one or both of these things ought to be done: - make extract-ikconfig not fail in such a case - [failing the prior one] enable /proc/config.gz by default, too Aww wait: I was mistaken in thinking that the config data is statically included in the kernel and configs.ko then is about providing /proc only. This not being the case (config data itself is provided by *module*, too) explains both my extract-ikconfig failure on the static kernel image and the size of configs.ko, so additionally enabling /proc/config.gz in this module most likely is a non-issue. However, this means that extract-ikconfig is missing a user error message indicating that the reason for lookup failure perhaps is that the setting is module-based and thus cannot be found in image (extract-ikconfig's header comments don't fully document this fact either). Will be creating a commit for this eventually (or do you want to add such thing to your patchset now? ;). Thanks for your effort, Andreas Mohr