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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 49BDAC2BB1D for ; Sat, 11 Apr 2020 01:02:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1BE74206A1 for ; Sat, 11 Apr 2020 01:02:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="G4wIcfT8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726827AbgDKBCI (ORCPT ); Fri, 10 Apr 2020 21:02:08 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:38737 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726791AbgDKBCI (ORCPT ); Fri, 10 Apr 2020 21:02:08 -0400 Received: by mail-qk1-f194.google.com with SMTP id h14so3944747qke.5; Fri, 10 Apr 2020 18:02:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=uCHZQqzsLUSZfwsYBU0j4Lk4ekCfYpHpyDR1Ei7qxqo=; b=G4wIcfT8Z/Y1ZgJCtGYPuYhSlZLb1wrNJjTWWGR45FGFVdtNXDf694qgDwG2EvyElL WOHEKt2sDQ13H5pYgJh94jg67eIQx2VyBimNt4TdmPyMggb0VtHPjqOwJ5t0RTNLFfhh LrE3F/IFtiJt7jEFheaOQQfNmeXIvg51orHRUN+VhwHGPhhQKIT1fEVFKp0/92osVCiA 8TF7PaYY39ScC4V9fl6ZSDQZRCDxaFF94bzW6bquOWWdcJBxUgw4iYD3g2X9iw416Lpc yMXU9iPTMbvf8qhT+hfF48vPz/HrJkBrPZVUiis85Exntlaa6qboiWwLw4FqXOlsTsSL S2ZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=uCHZQqzsLUSZfwsYBU0j4Lk4ekCfYpHpyDR1Ei7qxqo=; b=QvAzXsYz5gIyho6lxZAzBoYWyk+ERPIfMNjA+YlDwSItUeHeiJzcZ6luE0yL+IhKDG /2T2Q1KJvIxoeFC9j4Ntr8n5hvKkd3L0tZfZiTb1iDSZtTOhgBeSajRrUbZAE5nNHBSe 48zuhGtUGjqg5HTRCfACT7DCiYXv5DnIyq4YIWwl2vYu1dj27/P3TmdGs+Q5/XCsDqaf DI2Q1VuFf89zqiEpgVD7BicSss0Et0V0HmFtkCrOGBZeldxTnI0z2AfUVxcmSqYI0zy/ XKEpWBiN5yaljm4gbv2aRkxMA3LU02pjTiHxsgzNwbS/hsvK3zw/crI/3cSbJIrElo2y utKg== X-Gm-Message-State: AGi0PuYqhsaFscmVUTvbDPha8fqlw6nNK19B2ujnlSkm/aPTWfsvFEJO Gzvwj3OrlngwF82YS/Ei6gIbGzo+hC985A== X-Google-Smtp-Source: APiQypLy/o8e2yqRpsVXjOUFdLb6fmuFf4eiE2mr3OLlRD8EXOunNa1Djc3NiAa4fPjPpHdOHzunTw== X-Received: by 2002:a05:620a:c0b:: with SMTP id l11mr6513457qki.270.1586566926628; Fri, 10 Apr 2020 18:02:06 -0700 (PDT) Received: from darkstar ([177.89.165.183]) by smtp.gmail.com with ESMTPSA id y9sm2504142qkb.41.2020.04.10.18.02.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Apr 2020 18:02:06 -0700 (PDT) Date: Fri, 10 Apr 2020 22:02:01 -0300 From: Cristian Souza To: linux-kernel@vger.kernel.org Cc: linux-doc@vger.kernel.org, corbet@lwn.net, willy@infradead.org Subject: [PATCH v4] docs: admin-guide: Clarify sentences Message-ID: <20200411010201.GA22706@darkstar> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Changes to make the text more formal and organized. The reasons are now cited and described at the same time. Minor grammatical problems have also been fixed. Signed-off-by: Cristian Souza --- Changes in v2: - Text more formal and organized Changes in v3: - Authors at the top of the file - Removal of the source file in which the message is located - All lines under 80 characters Changes in v4: - Diff against mainline Documentation/admin-guide/init.rst | 76 ++++++++++++++---------------- 1 file changed, 36 insertions(+), 40 deletions(-) diff --git a/Documentation/admin-guide/init.rst b/Documentation/admin-guide/init.rst index e89d97f31eaf..41f06a09152e 100644 --- a/Documentation/admin-guide/init.rst +++ b/Documentation/admin-guide/init.rst @@ -1,52 +1,48 @@ -Explaining the dreaded "No init found." boot hang message +Explaining the "No working init found." boot hang message ========================================================= +:Authors: Andreas Mohr + Cristian Souza -OK, so you've got this pretty unintuitive message (currently located -in init/main.c) and are wondering what the H*** went wrong. -Some high-level reasons for failure (listed roughly in order of execution) -to load the init binary are: - -A) Unable to mount root FS -B) init binary doesn't exist on rootfs -C) broken console device -D) binary exists but dependencies not available -E) binary cannot be loaded - -Detailed explanations: - -A) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE) - to get more detailed kernel messages. -B) make sure you have the correct root FS type - (and ``root=`` kernel parameter points to the correct partition), - required drivers such as storage hardware (such as SCSI or USB!) - and filesystem (ext3, jffs2 etc.) are builtin (alternatively as modules, - to be pre-loaded by an initrd) -C) Possibly a conflict in ``console= setup`` --> initial console unavailable. - E.g. some serial consoles are unreliable due to serial IRQ issues (e.g. - missing interrupt-based configuration). +This document provides some high-level reasons for failure +(listed roughly in order of execution) to load the init binary. + +1) **Unable to mount root FS**: Set "debug" kernel parameter (in bootloader + config file or CONFIG_CMDLINE) to get more detailed kernel messages. + +2) **init binary doesn't exist on rootfs**: Make sure you have the correct + root FS type (and ``root=`` kernel parameter points to the correct + partition), required drivers such as storage hardware (such as SCSI or + USB!) and filesystem (ext3, jffs2, etc.) are builtin (alternatively as + modules, to be pre-loaded by an initrd). + +3) **Broken console device**: Possibly a conflict in ``console= setup`` + --> initial console unavailable. E.g. some serial consoles are unreliable + due to serial IRQ issues (e.g. missing interrupt-based configuration). Try using a different ``console= device`` or e.g. ``netconsole=``. -D) e.g. required library dependencies of the init binary such as - ``/lib/ld-linux.so.2`` missing or broken. Use - ``readelf -d |grep NEEDED`` to find out which libraries are required. -E) make sure the binary's architecture matches your hardware. - E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware. - In case you tried loading a non-binary file here (shell script?), - you should make sure that the script specifies an interpreter in its shebang - header line (``#!/...``) that is fully working (including its library - dependencies). And before tackling scripts, better first test a simple - non-script binary such as ``/bin/sh`` and confirm its successful execution. - To find out more, add code ``to init/main.c`` to display kernel_execve()s - return values. + +4) **Binary exists but dependencies not available**: E.g. required library + dependencies of the init binary such as ``/lib/ld-linux.so.2`` missing or + broken. Use ``readelf -d |grep NEEDED`` to find out which libraries + are required. + +5) **Binary cannot be loaded**: Make sure the binary's architecture matches + your hardware. E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM + hardware. In case you tried loading a non-binary file here (shell script?), + you should make sure that the script specifies an interpreter in its + shebang header line (``#!/...``) that is fully working (including its + library dependencies). And before tackling scripts, better first test a + simple non-script binary such as ``/bin/sh`` and confirm its successful + execution. To find out more, add code ``to init/main.c`` to display + kernel_execve()s return values. Please extend this explanation whenever you find new failure causes (after all loading the init binary is a CRITICAL and hard transition step -which needs to be made as painless as possible), then submit patch to LKML. +which needs to be made as painless as possible), then submit a patch to LKML. Further TODOs: - Implement the various ``run_init_process()`` invocations via a struct array which can then store the ``kernel_execve()`` result value and on failure log it all by iterating over **all** results (very important usability fix). -- try to make the implementation itself more helpful in general, - e.g. by providing additional error messages at affected places. +- Try to make the implementation itself more helpful in general, e.g. by + providing additional error messages at affected places. -Andreas Mohr -- 2.25.1