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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 13091C2BA83 for ; Fri, 14 Feb 2020 13:50:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2EC2222C4 for ; Fri, 14 Feb 2020 13:50:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729320AbgBNNuH (ORCPT ); Fri, 14 Feb 2020 08:50:07 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:54654 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728405AbgBNNuH (ORCPT ); Fri, 14 Feb 2020 08:50:07 -0500 Received: from localhost ([127.0.0.1] helo=vostro.local) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1j2bM3-0006JK-SH; Fri, 14 Feb 2020 14:50:04 +0100 From: John Ogness To: lijiang Cc: Petr Mladek , 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: [PATCH 2/2] printk: use the lockless ringbuffer References: <20200128161948.8524-1-john.ogness@linutronix.de> <20200128161948.8524-3-john.ogness@linutronix.de> Date: Fri, 14 Feb 2020 14:50:02 +0100 In-Reply-To: (lijiang@redhat.com's message of "Fri, 14 Feb 2020 21:29:23 +0800") Message-ID: <87zhdle0s5.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 Hi Lianbo, On 2020-02-14, lijiang wrote: >> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c >> index 1ef6f75d92f1..d0d24ee1d1f4 100644 >> --- a/kernel/printk/printk.c >> +++ b/kernel/printk/printk.c >> @@ -1062,21 +928,16 @@ void log_buf_vmcoreinfo_setup(void) >> { >> VMCOREINFO_SYMBOL(log_buf); >> VMCOREINFO_SYMBOL(log_buf_len); > > I notice that the "prb"(printk tb static) symbol is not exported into > vmcoreinfo as follows: > > + VMCOREINFO_SYMBOL(prb); > > 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. John Ogness