Received: by 2002:a25:1506:0:0:0:0:0 with SMTP id 6csp1773690ybv; Fri, 14 Feb 2020 05:50:48 -0800 (PST) X-Google-Smtp-Source: APXvYqyqMkSSpAL9nY03+erHsXmyVnLQnHrOS+Kp/eLRIWOA0JfN4BWHWOHz4UsmKfKxtSqGrQEj X-Received: by 2002:aca:c401:: with SMTP id u1mr1923358oif.62.1581688247941; Fri, 14 Feb 2020 05:50:47 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1581688247; cv=none; d=google.com; s=arc-20160816; b=xQLCtLbz7fQ8fPXIk+qyet9uVkzFWLi8FeBQczmBIaN5p2c5bSREwGtnAuGZfp7aj+ w9Dzte0h+woi9trlN3w/FCjORr6v2OUUqx+kdqJcbymg1L6yfXR902irrZPx6XH7CVq2 gfKNAL0WHYo/F9rYNkObRrxSWg0jtRz8cQ0oWJwWVAQEHHjkNfJjKulkN3lirHYWl5L9 JuipeVFMPabzPzZXo7N4EKqr3rCSp8vCFhNTC/nU1O8Lbb81KcAkHEMwRsb3sECie3Xn YY5xNAekN/fO7wxxa1MedRyM5zEiOFxlNwCeNPODoI2tYEHv2NFzvwBePpcRzJuAYnd7 ExQQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:user-agent:message-id :in-reply-to:date:references:subject:cc:to:from; bh=df+OvU+Pn7yKbIruXeUQ+iovj5KSaYPEu7kHxXF81qE=; b=JbacuLbM2kmlPztb6WJwZVKEyihj3v+QZ5RyTfpqWpbOW+11jJTJg4UpV4UFq5yuQz FmVxrzLp3EnHpNT0/hI7flElCFAN+1WVR4QycGwM9dz1C3Otk4yO9n6ym0+cHkuG1mhK UXJhLMrEhshHcRQUDvIbXMTCCdgmTIsaGRaN4A2XRPhhN+b8n7R06275T027SskShwzG epBTfhE69X3KRJTzcZ9CskAS4TSvkDAhb2fDOaokje6UoZFLS/4RgoWBrZ/sOYyFAb/m hXU/6A9SpkQV+rUIwPyg6CtpneGD5/8IFU0CgfQ0oAL4bsOhUINzXroFrNZNc/CtWAWf HB5g== ARC-Authentication-Results: i=1; mx.google.com; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y24si2795559oih.24.2020.02.14.05.50.35; Fri, 14 Feb 2020 05:50:47 -0800 (PST) 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; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729311AbgBNNuH (ORCPT + 99 others); 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