From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752781AbaINSF4 (ORCPT ); Sun, 14 Sep 2014 14:05:56 -0400 Received: from forward2l.mail.yandex.net ([84.201.143.145]:47568 "EHLO forward2l.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752533AbaINSFz (ORCPT ); Sun, 14 Sep 2014 14:05:55 -0400 X-Yandex-Uniq: a15e2561-effd-4f03-8674-7c1585e9d163 Authentication-Results: smtp16.mail.yandex.net; dkim=pass header.i=@yandex.ru Message-ID: <5415D8FA.8040305@yandex.ru> Date: Sun, 14 Sep 2014 22:05:46 +0400 From: Kirill Tkhai Reply-To: tkhai@yandex.ru User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.0 MIME-Version: 1.0 To: Greg KH CC: mmarek@suse.cz, arnd@arndb.de, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, oleg@redhat.com, grant.likely@secretlab.ca, ebiederm@xmission.com, akpm@linux-foundation.org, ktkhai@parallels.com, sam@ravnborg.org Subject: Re: [PATCH 0/3] Implement /proc/built-in file similar to /proc/modules References: <20140914100545.3745.23394.stgit@localhost> <20140914153832.GC4064@kroah.com> <5415D10E.90809@yandex.ru> <20140914173919.GA10059@kroah.com> In-Reply-To: <20140914173919.GA10059@kroah.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14.09.2014 21:39, Greg KH wrote: > On Sun, Sep 14, 2014 at 09:31:58PM +0400, Kirill Tkhai wrote: >> On 14.09.2014 19:38, Greg KH wrote: >>> On Sun, Sep 14, 2014 at 02:18:13PM +0400, Kirill Tkhai wrote: >>>> This series implements a possibility to show the list of built-in drivers >>>> to userspace. The names of drivers will be the same as when they are modules. >>> >>> Have you looked at /sys/modules/ ? Doesn't that show what you want >>> here? >> >> There are only the drivers in "/sys/module" which have parameters. >> Drivers without parameters do not appear there. > > Ah, didn't realize that. Should be easy to fix though, if you really > wanted to list the modules. Much better than a random proc file that > you have to parse :) But it looks like one file is better than many new directories. Furthermore some utils already may consider /sys/module directory as a directory where all drivers have parameters. Is it good if we add new ones of different type there? >>>> So, if your system has "loop" driver then it appears either in /proc/modules >>>> or in /proc/built-in and userspace will be able to know about this. >>>> >>>> Now this is impossible. The only way to get kernel configuration is >>>> /proc/config.gz, but CONFIG_* names can change from time to time. Module >>>> names are more or less standardized. >>> >>> Module names aren't "standardized", we change them at times when needed, >>> just like CONFIG_ names. >>> >>> What is your end goal here? As you say, config.gz is the real kernel >>> configuration, just having a list of modules built in isn't going to >>> help much in getting a working kernel config without it. >> >> It looks like userspace applications oriented on modules names rather >> than on CONFIG_XXX parameters. /proc/config.gz is optional and userspace >> applications can't base on it. >> >> For example, when I compile "loop" module built-in and "loop" is in >> /etc/modules, init script warns about this module is not present and >> can't be autoloaded. The script does not store CONFIG_XXX <-> module_xxx >> conformity. And nobody stores it. >> >> When iptables wants extra functionality, it requests a module. Etc. >> >> Nobody is oriented on CONFIG_XXX parameters. It would be simple for >> userspace to add a support of /proc/built-in analysing. It's very >> similar to /proc/modules. > > Shouldn't userspace focus on the functionality a module provides, not > the module name itself? Can't a test for the loop "module" just test to > see if the loop control device is present? Same for iptables (there's > modprobe rules for iptable modules I think...) > > In other words, don't focus on the module names, focus on the userspace > function a module provides, there should always be a way to check that > at run time (if not, then the module doesn't actually do much...) Hm, I'm not sure that anybody stores CONFIG_XXX <-> module_xxx conformity. Everybody bases on module name. If application is seeing CONFIG_XXX=m, but the functionality, which it want's, is not available, what it has to do? How should it convert CONFIG_XXX to module name? So, many applications want module name instead of CONFIG_XXX, I believe. Kirill