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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 4F8FAC4338F for ; Fri, 30 Jul 2021 11:00:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3042260FE7 for ; Fri, 30 Jul 2021 11:00:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238569AbhG3LAz (ORCPT ); Fri, 30 Jul 2021 07:00:55 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:49500 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238403AbhG3LAy (ORCPT ); Fri, 30 Jul 2021 07:00:54 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 5B9DB221A1; Fri, 30 Jul 2021 11:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1627642849; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vPU3VuVhAbVURPSkKGj0V9r87XsRlWqlHWR0ID/bNdw=; b=fL0XBylx5JiM+eWq7EdF4OmuBFZ/ENTjuXnaPABRpmz3EynS69AiaojvrEavO1jnELpyYm YDH/Y5KBINWs+tY3QQN5LL+J8wqsD48Hl+AzT/uymkUTraG5jeQHXhd5+SWHAPsEviTNtL nVvGbBfCl7DKk8f59uauHbJMfmI+cGE= Received: from suse.cz (unknown [10.100.224.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 3E98FA3B88; Fri, 30 Jul 2021 11:00:49 +0000 (UTC) Date: Fri, 30 Jul 2021 13:00:48 +0200 From: Petr Mladek To: Dmitry Safonov Cc: linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Andrew Morton , John Ogness , Sergey Senozhatsky , Steven Rostedt Subject: Re: [PATCH v2 2/2] printk: Add printk.console_verbose boot parameter Message-ID: References: <20210713011511.215808-1-dima@arista.com> <20210713011511.215808-3-dima@arista.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210713011511.215808-3-dima@arista.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2021-07-13 02:15:11, Dmitry Safonov wrote: > console_verbose() increases console loglevel to CONSOLE_LOGLEVEL_MOTORMOUTH, > which provides more information to debug a panic/oops. > > Unfortunately, in Arista we maintain some DUTs (Device Under Test) that > are configured to have 9600 baud rate. While verbose console messages > have their value to post-analyze crashes, on such setup they: > - may prevent panic/oops messages being printed > - take too long to flush on console resulting in watchdog reboot > > In all our setups we use kdump which saves dmesg buffer after panic, > so in reality those extra messages on console provide no additional value, > but rather add risk of not getting to __crash_kexec(). > > Provide printk.console_verbose boot parameter, which allows to switch off > printk being verbose on oops/panic/lockdep (making it boot parameter > instead of compile-option suggested-by Petr). > > Cc: Andrew Morton > Cc: John Ogness > Cc: Petr Mladek > Cc: Sergey Senozhatsky > Cc: Steven Rostedt > Signed-off-by: Dmitry Safonov Reviewed-by: Petr Mladek Tested-by: Petr Mladek Best Regards, Petr