From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757447Ab2GMUiG (ORCPT ); Fri, 13 Jul 2012 16:38:06 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:55700 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755334Ab2GMUiD (ORCPT ); Fri, 13 Jul 2012 16:38:03 -0400 MIME-Version: 1.0 From: Linus Torvalds Date: Fri, 13 Jul 2012 13:37:41 -0700 X-Google-Sender-Auth: -8qxUGjKVYHc5JfcqQYn2TuJ_o0 Message-ID: Subject: [RFC] Simplifying kernel configuration for distro issues To: Dave Jones , Greg Kroah-Hartman , Ubuntu Kernel Team , Debian Kernel Team , OpenSUSE Kernel Team Cc: Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So this has long been one of my pet configuration peeves: as a user I am perfectly happy answering the questions about what kinds of hardware I want the kernel to support (I kind of know that), but many of the "support infrastructure" questions are very opaque, and I have no idea which of the them any particular distribution actually depends on. And it tends to change over time. For example, F14 (iirc) started using TMPFS and TMPFS_POSIX_ACL/XATTR for /dev. And starting in F16, the initrd setup requires DEVTMPFS and DEVTMPFS_MOUNT. There's been several times when I started with my old minimal config, and the resulting kernel would boot, but something wouldn't quite work right, and it can be very subtle indeed. Similarly, the distro ends up having very particular requirements for exactly *which* security models it uses and needs, and they tend to change over time. And now with systemd, CGROUPS suddenly aren't just esoteric things that no normal person would want to use, but are used for basic infrastructure. And I remember being surprised by OpenSUSE suddenly needing the RAW table support for netfilter, because it had a NOTRACK rule or something. The point I'm slowly getting to is that I would actually love to have *distro* Kconfig-files, where the distribution would be able to say "These are the minimums I *require* to work". So we'd have a "Distro" submenu, where you could pick the distro(s) you use, and then pick which release, and we'd have something like - distro/Kconfig: config DISTRO_REQUIREMENTS bool "Pick minimal distribution requirements" choice DISTRO prompt "Distribution" depends on DISTRO_REQUIREMENTS config FEDORA config OPENSUSE config UBUNTU ... endchoice and then depending on the DISTRO config, we'd include one of the distro-specific ones with lists of supported distro versions and then the random config settings for that version: - distro/Kconfig.suse: config OPENSUSE_121 select OPENSUSE_11 select IP_NF_RAW # .. - distro/Kconfig.Fedora: config FEDORA_16 select FEDORA_15 select DEVTMPFS # F16 initrd needs this select DEVTMPFS_MOUNT # .. and expects the kernel to mount DEVTMPFS automatically ... config FEDORA_17 select FEDORA_16 select CGROUP_xyzzy ... and the point would be that it would make it much easier for a normal user (and quite frankly, I want to put myself in that group too) to make a kernel config that "just works". Sure, you can copy the config file that came with the distro, but it has tons of stuff that really isn't required. Not just in hardware, but all the debug choices etc that are really a user choice. And it's really hard to figure out - even for somebody like me - what a minimal usable kernel is. And yes, I know about "make localmodconfig". That's missing the point for the same reason the distro config is missing the point. Comments? It doesn't have to start out perfect, but I think it would *really* help make the kernel configuration much easier for people. In addition to the "minimal distro settings", we might also have a few "common platform" settings, so that you could basically do a "hey, I have a modern PC laptop, make it pick the obvious stuff that a normal person needs, like USB storage, FAT/VFAT support, the core power management etc". The silly stuff that you need, and that "localyesconfig" actually misses because if you haven't inserted a USB thumb drive, you won't necessarily have the FAT module loaded, but we all know you do want it in real life. But that's really independent issue, so let's keep it to just distro core things at first, ok? Would something like this make sense to people? I really think that "How do I generate a kernel config file" is one of those things that keeps normal people from compiling their own kernel. And we *want* people to compile their own kernel so that they can help with things like bisecting etc. The more, the merrier. Linus