From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B2DEC43219 for ; Mon, 29 Apr 2019 15:09:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD9ED205ED for ; Mon, 29 Apr 2019 15:09:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="BErTn8Ec" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728366AbfD2PJd (ORCPT ); Mon, 29 Apr 2019 11:09:33 -0400 Received: from conssluserg-04.nifty.com ([210.131.2.83]:57877 "EHLO conssluserg-04.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728253AbfD2PJd (ORCPT ); Mon, 29 Apr 2019 11:09:33 -0400 Received: from mail-ua1-f51.google.com (mail-ua1-f51.google.com [209.85.222.51]) (authenticated) by conssluserg-04.nifty.com with ESMTP id x3TF9KC8006419; Tue, 30 Apr 2019 00:09:21 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-04.nifty.com x3TF9KC8006419 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1556550561; bh=MW1aGUukyb5H+fRSy4kTMiPDEchWe4IFhiW9Utfmjp8=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=BErTn8EcfVgazUjgbaVzOqESVQn3n51PzT0778Socc5TcBBrGZCGGohxkDq1MgW94 Iwks6bwmTwbSefpQCRrYtxUGmPNmLDWmawEgSuOCXQIu2NqSNjfNOXwB3qPLuovE5r HTyQlkNgtqOkgTdgc81A3LEEyeOFBe/Hq+/dNZYFp48oXh9cPOdc2viG3hTo9XpT+Q Q7O76I7aO1I5eifl23gZDP/9SKNBGwhp0a80C7kLTc1tYJjHbPWkgF7IE085JWGfk1 cqpTAEzKnCD3l0ZK9uWFCNtwYFjPopBJRcxdjFtRIDVfXpytay+74JV1UMqWzcKdZl 9MFy48RqhW29g== X-Nifty-SrcIP: [209.85.222.51] Received: by mail-ua1-f51.google.com with SMTP id h4so3600107uaj.9; Mon, 29 Apr 2019 08:09:21 -0700 (PDT) X-Gm-Message-State: APjAAAUUyfzvK6dJ5qZQNqmenek2T77Nr7Ki/2UJqoqi2753KDptmy3W tfGlZW3hnhF9LybE5wRFM157C8pVO4pClv1HLzQ= X-Google-Smtp-Source: APXvYqxkwcGqg1dUxJR5uNJzQww6ku12Zq9V2fnR5+weRvJDt+V0L3rkBfD0KFczMq29mFbSW64iIFLza3fW+6g0ZaI= X-Received: by 2002:ab0:3058:: with SMTP id x24mr6928895ual.95.1556550560107; Mon, 29 Apr 2019 08:09:20 -0700 (PDT) MIME-Version: 1.0 References: <20190429090854.GU9023@dhcp129-178.brq.redhat.com> In-Reply-To: <20190429090854.GU9023@dhcp129-178.brq.redhat.com> From: Masahiro Yamada Date: Tue, 30 Apr 2019 00:08:44 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3] moduleparam: Save information about built-in modules in separate file To: Alexey Gladkov Cc: 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 , Jessica Yu , Lucas De Marchi Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-modules@vger.kernel.org Precedence: bulk List-ID: On Mon, Apr 29, 2019 at 6:09 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; > * Add MODULE_VERSION to modinfo that is saved to the kernel.builtin; > * Fix build warnings on powerpc. > > v3: > * Rename output file to modules.builtin.modinfo as suggested by Masahiro Yamada; > * Update Documentation/dontdiff, Documentation/kbuild/kbuild.txt. > > Co-Developed-by: Gleb Fotengauer-Malinovskiy > Signed-off-by: Gleb Fotengauer-Malinovskiy > Signed-off-by: Alexey Gladkov > --- > .gitignore | 1 + > Documentation/dontdiff | 1 + > Documentation/kbuild/kbuild.txt | 5 +++++ > Makefile | 2 ++ > include/asm-generic/vmlinux.lds.h | 1 + > include/linux/module.h | 1 + > include/linux/moduleparam.h | 12 +++++------- > scripts/link-vmlinux.sh | 4 ++++ > 8 files changed, 20 insertions(+), 7 deletions(-) > > diff --git a/.gitignore b/.gitignore > index a20ac26aa2f5..8ef2c87703b3 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -45,6 +45,7 @@ > *.xz > Module.symvers > modules.builtin > +modules.builtin.modinfo > > # > # Top-level generic files Let me repeat the same comments as in v2 (https://patchwork.kernel.org/patch/10888207/#22595563) as you ignored them. This file is generated only in the top of the tree. Please add '/' prefix and move it to the "# Top-level generic files" section. # # Top-level generic files # /tags /TAGS /linux /vmlinux /vmlinux.32 /vmlinux-gdb.py /vmlinuz /System.map /Module.markers /modules.builtin.modinfo > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index c8cf45362bd6..41ef7cb043c1 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -226,6 +226,10 @@ modpost_link vmlinux.o > # modpost vmlinux.o to check for section mismatches > ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o > > +info MODINFO modules.builtin.modinfo > +"${OBJCOPY}" -j .modinfo -O binary vmlinux.o modules.builtin.modinfo > +chmod 444 modules.builtin.modinfo Why is this 'chmod 444' necessary? > + > kallsymso="" > kallsyms_vmlinux="" > if [ -n "${CONFIG_KALLSYMS}" ]; then -- Best Regards Masahiro Yamada