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=-5.8 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 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 813E1C432BE for ; Wed, 1 Sep 2021 11:48:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 650FB61090 for ; Wed, 1 Sep 2021 11:48:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243876AbhIALtg (ORCPT ); Wed, 1 Sep 2021 07:49:36 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:52924 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233116AbhIALtf (ORCPT ); Wed, 1 Sep 2021 07:49:35 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id C18752252B; Wed, 1 Sep 2021 11:48:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1630496917; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=r86Qp0j14moY0c9BdKYGjByM22DynjsO0TI01C7umvY=; b=NFWHX/B1vAc6YABOInFrmYNw2eInR+iBHZ+VH/hfhirp+xm7GjTBx/NISkb2ooa2uSjh5a s4EIzX3Xs6dUu450J/riTS1Hb9Xv+U/PQEWkJec2MNxo/R37OjfBzKsagx6AGE0WpAZBO2 J8oI1aFhUvJgVpjnF/WFpRQ2p63RmUs= Received: from suse.cz (unknown [10.100.216.66]) (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 5ABE6A3B9F; Wed, 1 Sep 2021 11:48:37 +0000 (UTC) Date: Wed, 1 Sep 2021 13:48:33 +0200 From: Petr Mladek To: James Wang Cc: Sergey Senozhatsky , Linus Torvalds , Steven Rostedt , John Ogness , Linux Kernel Mailing List Subject: Re: kernel hang during reboot when cmdline include a non-exist console device Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2021-09-01 09:52:54, James Wang wrote: > > 在 2021/8/31 PM10:52, Petr Mladek 写道: > > On Tue 2021-08-31 22:38:42, James Wang wrote: > > > 在 2021/8/31 PM10:33, Petr Mladek 写道: > > > > On Tue 2021-08-31 21:45:05, James Wang wrote: > > > > > 在 2021/8/31 PM4:47, Sergey Senozhatsky 写道: > > > > > > And may I ask, just in case, if James can revert a revert of Petr's commit: > > > > > > > > > > > > revert a91bd6223ecd46addc71ee6fcd432206d39365d2 > > > > > > > > > > > > boot with wrong console argument and see if the kernel reboots without > > > > > > any problems. > > > > > After test, revert Petr's commit can work; reboot without any problem; > > > > Interesting, it looks like the panic() is really caused by missing > > > > stdout, stdin, and stderr, for the init process. > > > > > > > > Unfortunately, the fix is not easy, as described in the commit > > > > a91bd6223ecd46addc71e ("Revert "init/console: Use ttynull as > > > > a fallback when there is no console"). > > > OK. But I suppose you could find a quick workaround to mitigate this issue. > > You could either remove the invalid console=ttyUSB0,115200 > > parameter. As a result, tty0 will become the default console and > > it will be used by the init process. > > No，I just want to use a "invalid" console parameter for "boot up", because > It could help me "drop" kernel/systemd log, keep the kernel logo on the > screen; This looks like a hack. And it works just by chance. It is neither documented nor supported. The official way to hide kernel messages is using "quiet" or "loglevel=1" kernel parameters. If you really do not want the console then I suggest to use the ttynull driver mentioned in the previous mail. Best Regards, Petr