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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 C8510C34022 for ; Mon, 17 Feb 2020 16:14:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9BEFA20718 for ; Mon, 17 Feb 2020 16:14:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728595AbgBQQO2 (ORCPT ); Mon, 17 Feb 2020 11:14:28 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:60203 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728138AbgBQQO2 (ORCPT ); Mon, 17 Feb 2020 11:14:28 -0500 Received: from localhost ([127.0.0.1] helo=vostro.local) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1j3j2N-0001Hx-Sj; Mon, 17 Feb 2020 17:14:23 +0100 From: John Ogness To: Petr Mladek Cc: lijiang , Peter Zijlstra , Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: crashdump: Re: [PATCH 2/2] printk: use the lockless ringbuffer References: <20200128161948.8524-1-john.ogness@linutronix.de> <20200128161948.8524-3-john.ogness@linutronix.de> <87zhdle0s5.fsf@linutronix.de> <20200217154026.7x2xyrklprgql4if@pathway.suse.cz> Date: Mon, 17 Feb 2020 17:14:22 +0100 In-Reply-To: <20200217154026.7x2xyrklprgql4if@pathway.suse.cz> (Petr Mladek's message of "Mon, 17 Feb 2020 16:40:26 +0100") Message-ID: <87zhdh9oo1.fsf@linutronix.de> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-02-17, Petr Mladek wrote: >>> Should the "prb"(printk tb static) symbol be exported into >>> vmcoreinfo? Otherwise, do you happen to know how to walk through >>> the log_buf and get all kernel logs from vmcore? >> >> You are correct. This will need to be exported as well so that the >> descriptors can be accessed. (log_buf is only the pure human-readable >> text.) I am currently hacking the crash tool to see exactly what >> needs to be made available in order to access all the data of the >> ringbuffer. > > I am not sure which parts you are working on. Are you going to provide > also patch for makedumpfile, please? I'm working on crash first. makedumpfile is on my list as well. > I get the following failure when creating the crashdump using: > > echo c >/proc/sysrq-trigger > > > The kernel version is not supported. > The makedumpfile operation may be incomplete. > dump_dmesg: Can't find variable-length record symbols > makedumpfile Failed. > Running makedumpfile --dump-dmesg /proc/vmcore failed (1). Yes, the symbols have changed (and some are missing). I will get this sorted out for v2. And I will provide some heavily hacked code for crash and makedumpfile to show that the necessary symbols are there and it works. John Ogness