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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 7A8E2C433E9 for ; Thu, 7 Jan 2021 17:47:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4AA68233FD for ; Thu, 7 Jan 2021 17:47:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728831AbhAGRr1 (ORCPT ); Thu, 7 Jan 2021 12:47:27 -0500 Received: from mga02.intel.com ([134.134.136.20]:53102 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726073AbhAGRr1 (ORCPT ); Thu, 7 Jan 2021 12:47:27 -0500 IronPort-SDR: rYwECGs3wX7dkg6Usi0/QnLZeWbeozH5uikpMeWiUGoZdj718wySGLi5Hq+ywQmOrazp8d44sa DgWx7VLjt1tw== X-IronPort-AV: E=McAfee;i="6000,8403,9857"; a="164535496" X-IronPort-AV: E=Sophos;i="5.79,329,1602572400"; d="scan'208";a="164535496" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jan 2021 09:45:39 -0800 IronPort-SDR: ZcrPIhtEdY5p2Oa7/7GfEhGWJ2eNA+sB1RalhfQ6IWja9h5VvV91BcXFyTymJXxCSMK+YryGeR T1IFXZtJvJYw== X-IronPort-AV: E=Sophos;i="5.79,329,1602572400"; d="scan'208";a="396032066" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jan 2021 09:45:36 -0800 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kxZMs-0050uv-6C; Thu, 07 Jan 2021 19:46:38 +0200 Date: Thu, 7 Jan 2021 19:46:38 +0200 From: Andy Shevchenko To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , John Ogness , Linus Torvalds , Guenter Roeck , Shreyas Joshi , shreyasjoshi15@gmail.com, Greg Kroah-Hartman , Sergey Senozhatsky , Greg Ungerer , Vineet Gupta , Thomas Meyer , David Gow , Brendan Higgins , Shuah Khan , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] Revert "init/console: Use ttynull as a fallback when there is no console" Message-ID: <20210107174638.GH4077@smile.fi.intel.com> References: <20210107164400.17904-1-pmladek@suse.com> <20210107164400.17904-2-pmladek@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210107164400.17904-2-pmladek@suse.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 07, 2021 at 05:44:00PM +0100, Petr Mladek wrote: > This reverts commit 757055ae8dedf5333af17b3b5b4b70ba9bc9da4e. > > The commit caused that ttynull was used as the default console > on many systems. It happened when there was no console configured > on the command line and ttynull_init() was the first initcall > calling register_console(). > > The commit fixed a historical problem that have been there for ages. > The primary motivation was the commit 3cffa06aeef7ece30f6 > ("printk/console: Allow to disable console output by using console="" > or console=null"). It provided a clean solution > for a workaround that was widely used and worked only by chance. > > This revert causes that the console="" or console=null command line > options will again work only by chance. These options will cause that > a particular console will be preferred and the default (tty) ones > will not get enabled. There will be no console registered at > all. As a result there won't be stdin, stdout, and stderr for > the init process. But it worked exactly this way even before. > > The proper solution has to fulfill many conditions: > > + Register ttynull only when explicitly required or as > the ultimate fallback. > > + ttynull must get associated with /dev/console but it must > not become preferred console when used as a fallback. > Especially, it must still be possible to replace it > by a better console later. > > Such a change requires clean up of the register_console() code. > Otherwise, it would be even harder to follow. Especially, the use > of has_preferred_console and CON_CONSDEV flag is tricky. The clean > up is risky. The ordering of consoles is not well defined. And > any changes tend to break existing user settings. > > Do the revert at the least risky solution for now. Shouldn't it have Fixes tag along with Reported-by ones and explanation what was the actual problem reported? -- With Best Regards, Andy Shevchenko