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[209.132.180.67]) by mx.google.com with ESMTP id r24si2239829pls.398.2019.04.18.07.39.06; Thu, 18 Apr 2019 07:39:21 -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=@gmail.com header.s=20161025 header.b=CyOlkmdI; 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; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389390AbfDROgq (ORCPT + 99 others); Thu, 18 Apr 2019 10:36:46 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:51919 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388907AbfDROgo (ORCPT ); Thu, 18 Apr 2019 10:36:44 -0400 Received: by mail-wm1-f65.google.com with SMTP id 4so3040185wmf.1; Thu, 18 Apr 2019 07:36:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kZebXCDZh23oSVAps9/qDaV/3OsIk6+l4osGFKchiqk=; b=CyOlkmdIy7KxwPiBuHtn3v4aJgge89+1g38yBJ0r+jNLyNMUiSthGM+OBocfMsB3Ew Y/uqmjoxAHH3XqmufrGHCNii7qiIRInlV7Q17nQSXLUtqpjdFV/Jb21ZCLdxg14vPjU3 ZROAisMMcZgB13ty3o0OSD4zDK6dQadZ3RWSKVdl1WlHKpaGADm2kRGApuIHIYkb37xd qd9reVuVFjoFMmxfvXx2bUymNplsgdm1sYGi17vnXrF8vEynj3scJ0W50ie1AEeyFABj ZgeM/Av97qyV1p28qF22G68VAUoIax071wpvB4gbOpWjsPzSlf/+n6awJQgzY84m3PZ7 D6cg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kZebXCDZh23oSVAps9/qDaV/3OsIk6+l4osGFKchiqk=; b=oybjx0vMMcTuk4WxQf1wrfR/1wdhnX8h9iQevDqt2UXUagd3iZVqqTDFiLYbJ7V3Av 0NGgogMjIo1bl1c8mAY9L3dXawPdQLWOxQcF7p0FvonaeaMhqvx8Y3pIeCJNJGLpxlb7 H1Xxk+j+ivx6In32RJcKgGIy7uUsS8DZLpW+fkC0o/JeDBpoC+JrBK60xsLxPTdWjBnB N2JmCnGM21wq2JJBl4mV0UOlyRHk7mp+ghb7NowCqAYjSVCYXueGZtNRnqV7NWi2lfTz 0qvaMhVevqqZtlp7lVHUsbv3bpv1iSGuoT5e+Gq8bgjVkdR0WkmzbBatWAORAo0zNz2+ GNNQ== X-Gm-Message-State: APjAAAUxQbKajZXMTEEHfe2Wa+uJYQN7WbsYqdklzP21fsO6n7NQmoP4 MIfu5U9LM0i8VI+5h8EbbIRw7DZgFU0jtR9kb+w= X-Received: by 2002:a1c:dc84:: with SMTP id t126mr3252812wmg.143.1555598202270; Thu, 18 Apr 2019 07:36:42 -0700 (PDT) MIME-Version: 1.0 References: <20190406121447.GB4047@localhost.localdomain> <20190418135238.GA5626@linux-8ccs> In-Reply-To: <20190418135238.GA5626@linux-8ccs> From: Lucas De Marchi Date: Thu, 18 Apr 2019 07:36:25 -0700 Message-ID: Subject: Re: [PATCH v2] moduleparam: Save information about built-in modules in separate file To: Jessica Yu Cc: Masahiro Yamada , Alexey Gladkov , Linux Kernel Mailing List , Linux Kbuild mailing list , linux-api@vger.kernel.org, linux-modules , "Kirill A . Shutemov" , Gleb Fotengauer-Malinovskiy , "Dmitry V. Levin" , Michal Marek , Dmitry Torokhov , Rusty Russell 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 6:52 AM 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 I agree with modules.builtin.modinfo > names consistent with what is already there? 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. I think it's ok with the current format. It's simple enough. I would delay merging it until the userspace counterpart is implemented though. So to make sure we have everything we need. I can work on that in ~1 or 2 weeks. thanks Lucas De Marchi > > Also, I think this file needs to be documented in Documentation/kbuild/kbuild.txt. > > Thanks, > > Jessica -- Lucas De Marchi