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[209.132.180.67]) by mx.google.com with ESMTP id u10si2073929pga.205.2019.04.18.08.28.38; Thu, 18 Apr 2019 08:28:54 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@nifty.com header.s=dec2015msa header.b=RcGv2MsV; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388888AbfDRP1a (ORCPT + 99 others); Thu, 18 Apr 2019 11:27:30 -0400 Received: from conssluserg-02.nifty.com ([210.131.2.81]:28274 "EHLO conssluserg-02.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731317AbfDRP1a (ORCPT ); Thu, 18 Apr 2019 11:27:30 -0400 X-Greylist: delayed 15376 seconds by postgrey-1.27 at vger.kernel.org; Thu, 18 Apr 2019 11:27:28 EDT Received: from mail-vs1-f49.google.com (mail-vs1-f49.google.com [209.85.217.49]) (authenticated) by conssluserg-02.nifty.com with ESMTP id x3IFRAI1000644; Fri, 19 Apr 2019 00:27:10 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-02.nifty.com x3IFRAI1000644 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1555601231; bh=IZhFShJ6jDiysCuABWEkQgQvv5e4ZaTURElBN4UyQy8=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=RcGv2MsVY9871J747cWMrMvVAJrvKtzcous8CoBAOH4ZTw1RFFdKfWrhFUSZs+BTA MmmKd26RRXLeHHXpiDeemnE4mXrz4jf4EQvts5p1S0lp76qkgMZA8erHdGzvlgF9/o MZgWYw8eqvoYsU05enUbPD283kbMm0+pZvw3f7UQrlkGIRkHJieJv6Dw+lN5dpQxPz wXpWFp7pL9wgqFK7XByS8mB7wNG3JNfv/d2U5C+QruqfoNzzIK5A9STYxsAQhXa1/3 7+7DTGLksLJPOGX/4NXJbh1Bm2/wdrayx77fWLzS0eSnlduC5HR60LTCzcQLKq2K4j N2YyM0n/VDP7w== X-Nifty-SrcIP: [209.85.217.49] Received: by mail-vs1-f49.google.com with SMTP id g127so1372552vsd.6; Thu, 18 Apr 2019 08:27:10 -0700 (PDT) X-Gm-Message-State: APjAAAVcEdLFwvv0T5BDNutyiKtQ5wpSc7y1nZCJNMrW6gN5e0cZZvzb J61Gj8W+MeccAEdtO8uWdSeWDspZ2Hq51snpcjc= X-Received: by 2002:a67:f948:: with SMTP id u8mr9436544vsq.179.1555601229490; Thu, 18 Apr 2019 08:27:09 -0700 (PDT) MIME-Version: 1.0 References: <20190406121447.GB4047@localhost.localdomain> <20190418135238.GA5626@linux-8ccs> In-Reply-To: <20190418135238.GA5626@linux-8ccs> From: Masahiro Yamada Date: Fri, 19 Apr 2019 00:26:33 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] moduleparam: Save information about built-in modules in separate file To: Jessica Yu Cc: Alexey Gladkov , Linux Kernel Mailing List , Linux Kbuild mailing list , linux-api@vger.kernel.org, linux-modules@vger.kernel.org, "Kirill A . Shutemov" , Gleb Fotengauer-Malinovskiy , "Dmitry V. Levin" , Michal Marek , Dmitry Torokhov , Rusty Russell , Lucas De Marchi Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 18, 2019 at 10:52 PM Jessica Yu wrote: > > +++ Masahiro Yamada [18/04/19 20:10 +0900]: > >On Sat, Apr 6, 2019 at 9:15 PM Alexey Gladkov wrote: > >> > >> Problem: > >> > >> When a kernel module is compiled as a separate module, some important > >> information about the kernel module is available via .modinfo section of > >> the module. In contrast, when the kernel module is compiled into the > >> kernel, that information is not available. > >> > >> Information about built-in modules is necessary in the following cases: > >> > >> 1. When it is necessary to find out what additional parameters can be > >> passed to the kernel at boot time. > >> > >> 2. When you need to know which module names and their aliases are in > >> the kernel. This is very useful for creating an initrd image. > >> > >> Proposal: > >> > >> The proposed patch does not remove .modinfo section with module > >> information from the vmlinux at the build time and saves it into a > >> separate file after kernel linking. So, the kernel does not increase in > >> size and no additional information remains in it. Information is stored > >> in the same format as in the separate modules (null-terminated string > >> array). Because the .modinfo section is already exported with a separate > >> modules, we are not creating a new API. > >> > >> It can be easily read in the userspace: > >> > >> $ tr '\0' '\n' < kernel.builtin > >> ext4.softdep=pre: crc32c > >> ext4.license=GPL > >> ext4.description=Fourth Extended Filesystem > >> ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others > >> ext4.alias=fs-ext4 > >> ext4.alias=ext3 > >> ext4.alias=fs-ext3 > >> ext4.alias=ext2 > >> ext4.alias=fs-ext2 > >> md_mod.alias=block-major-9-* > >> md_mod.alias=md > >> md_mod.description=MD RAID framework > >> md_mod.license=GPL > >> md_mod.parmtype=create_on_open:bool > >> md_mod.parmtype=start_dirty_degraded:int > >> ... > >> > >> v2: > >> * Extract modinfo from vmlinux.o as suggested by Masahiro Yamada; > >> * Rename output file to kernel.builtin; > > > >Sorry, I do not get why you renamed > >"kernel.builtin.modinfo" to "kernel.builtin". > > > >If you drop "modinfo", we do not understand > >what kind information is contained in it. > > > >I think "kernel" and "builtin" have > >a quite similar meaning here. > > > >How about "builtin.modinfo" for example? > > > > > >It is shorter, and it is clear enough > >that it contains module_info. > > I agree that the name kernel.builtin is unclear in what kind of > information it contains. Apologies for not having clarified this in > the previous review. > > Since kbuild already produces "modules.order" and "modules.builtin" > files, why not just name it "modules.builtin.modinfo" to keep the > names consistent with what is already there? Is it consistent? If we had "modules.order" and "modules.builtin.order" there, I would agree with "modules.builtin.modinfo", and also "modules.alias" vs "modules.builtin.alias". We already have "modules.builtin", and probably impossible to rename it, so we cannot keep consistency in any way. "modules.builtin" is a weird name since it actually contains "order", but its extension does not express what kind of information is in it. Hence, I doubt "modules.builtin" is a good precedent. IMHO, "modules" and "builtin" are opposite to each other. "modules.builtin" sounds iffy to me. > It clearly conveys that > this file contains modinfo for builtin modules. > > I'll leave it up to Lucas to decide if the file format is OK for kmod. > With the modinfo dump, kmod could then decide what to do with the > information, append to modules.alias{,.bin}, etc. > > Also, I think this file needs to be documented in Documentation/kbuild/kbuild.txt. > > Thanks, > > Jessica -- Best Regards Masahiro Yamada