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,URIBL_RED 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 82A34C433E0 for ; Thu, 7 Jan 2021 19:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 476132343E for ; Thu, 7 Jan 2021 19:16:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728705AbhAGTQB (ORCPT ); Thu, 7 Jan 2021 14:16:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:42722 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725835AbhAGTQA (ORCPT ); Thu, 7 Jan 2021 14:16:00 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B75072343E; Thu, 7 Jan 2021 19:15:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610046920; bh=eVbf8+HJ1mj8sG5PUsuFmbQMq89wv8eiPNTQRTzGhQc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=08Nytn/LI4ieeCIDrw+lZcGhcDdz7u3YZBv5pHx0ShKjFDcmENZQiFBg6xfx3p2hy 0TVOdTb0hXWXzS3BpESvTzy6NqgTkUrMgLRiE34jGPfw5H9lXWk2z3cDJypG+yANzo uVYwjCZ17gsXn1dT3H2sruDGAs+gg6+hX+nIFXuQ= Date: Thu, 7 Jan 2021 20:16:39 +0100 From: Greg Kroah-Hartman To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , John Ogness , Linus Torvalds , Guenter Roeck , Shreyas Joshi , shreyasjoshi15@gmail.com, Sergey Senozhatsky , Greg Ungerer , Vineet Gupta , Thomas Meyer , David Gow , Brendan Higgins , Andy Shevchenko , 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: 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> 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. > > Signed-off-by: Petr Mladek Acked-by: Greg Kroah-Hartman Linus, can you take this directly, or is this going through some other tree? thanks, greg k-h