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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 04A8DC41604 for ; Tue, 6 Oct 2020 16:35:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 98DA8206F7 for ; Tue, 6 Oct 2020 16:35:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Pe6WPbvO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726396AbgJFQfR (ORCPT ); Tue, 6 Oct 2020 12:35:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:46622 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725947AbgJFQfR (ORCPT ); Tue, 6 Oct 2020 12:35:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602002115; h=from:from:reply-to:subject:subject: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=otPJ9dbCjuwwNchIDB5rytsiy123wjN6QIlkbo3Pfqw=; b=Pe6WPbvO8ij8x+wxHXCsvtjCuCFVuYPU0KjCN8QudcYOpQBTUShifOyAggE5NeuaSib4MH iWoPUM/XagOmqR5GYnPt3Y4umhS3QH2ZIIXDcyyZfRrt0/av7pjhdXI71QqizFUP31/3rc fb8elwSiCvp4mbCrkXtlVdwM6XE3Gyo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 410E7AE79; Tue, 6 Oct 2020 16:35:15 +0000 (UTC) Date: Tue, 6 Oct 2020 18:35:14 +0200 From: Petr Mladek To: Guenter Roeck Cc: Sergey Senozhatsky , Shreyas Joshi , rostedt@goodmis.org, shreyasjoshi15@gmail.com, linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Linus Torvalds Subject: Re: [PATCH] printk: handle blank console arguments passed in. Message-ID: <20201006163514.GE32369@alley> References: <20200522065306.83-1-shreyas.joshi@biamp.com> <20200522100046.GH3464@linux-b0ei> <20201006025935.GA597@jagdpanzerIV.localdomain> <20201006095226.GB32369@alley> <24f7a6bc-c917-2bb7-0e86-9d729c18e812@roeck-us.net> <20201006134328.GD32369@alley> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201006134328.GD32369@alley> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2020-10-06 15:43:28, Petr Mladek wrote: > On Tue 2020-10-06 03:45:00, Guenter Roeck wrote: > > On 10/6/20 2:52 AM, Petr Mladek wrote: > > > And it makes perfect sense to disable all consoles or drop all defined > > > by dts. But I would prefer to make it more obvious way, for > > > example by parameters like: > > > > > > + console=none > > > + no-console > > > + no-dtd-console > > > + no-default-console > > > > > Again, the problem isn't limited to dts provided consoles, or at least > > that was my understanding. I am still trying to understand how default > > consoles are defined, so I may get something wrong. Anyway, personally I > > liked "console=", but that is just me. Anything else should work for us > > as long as it is backward compatible (which excludes the no-xxx options). > > Here is my understanding: > > The consoles can be defined by scpr, dts, and on the command line. It > is anyone calling add_preferred_console(). > > Then the various devices call register_console(). They are registered > only when they match any console in console_cmdline[] array, see > try_enable_new_console(). > > > Whatever is decided, I'd like to have it made official and documented to > > avoid a similar problem in the future. Sigh, it is even bigger mess than I expected. There is a magic variable "console_set_on_cmdline". It used, for example, in of_console_check() to prevent using the default console from dts. It is used on few more locations to prevent the default console. But there are other locations when add_preferred_console() is called without checking this variable. As a result, "console=" has different effect on different systems. I tend to revert the problematic patch now. And I would try to clean up this mess for-5.11. There is a big chance that people used the empty console= only on systems where it disabled all default consoles. I would try to make it the official global behavior. But this would need some longer testing in linux-next, ... Best Regards, Petr