From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754374AbdGNOh5 (ORCPT ); Fri, 14 Jul 2017 10:37:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:33614 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754026AbdGNOhz (ORCPT ); Fri, 14 Jul 2017 10:37:55 -0400 Date: Fri, 14 Jul 2017 16:37:52 +0200 From: Petr Mladek To: "Fabio M. Di Nitto" Cc: Sergey Senozhatsky , Steven Rostedt , Andrew Morton , Peter Zijlstra , Matt Redfearn , Greg Kroah-Hartman , Jiri Slaby , "David S. Miller" , Alan Cox , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: [PATCH 0/2] Avoid crashes by early (boot) consoles using init memory Message-ID: <20170714143751.GB32632@pathway.suse.cz> References: <1500036673-7122-1-git-send-email-pmladek@suse.com> <956ce40c-1640-387a-0ec9-9045c7d8af4b@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <956ce40c-1640-387a-0ec9-9045c7d8af4b@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 2017-07-14 14:57:45, Fabio M. Di Nitto wrote: > Hi Petr, > > On 7/14/2017 2:51 PM, Petr Mladek wrote: > > Some early consoles have code and data in the init section. It makes some > > sense but this might cause problems when they are not replaced by > > the real console in time. The two patches fix the safequard and > > help to avoid the problems. > > > > I though about removing keep_bootcon option completely. But it is useful > > at least for now. > > Letīs just keep in mind that keep_bootcon was introduced only to debug > issues (read crashes or hangs) that could happen between disabling > bootconsole and enabling the real console. It shouldnīt be used for > anything else really. This was my initial replay as well. But then I realized that it was a bad idea to use a freed code and data to debug any other issue. It would just create crazy issues on its own. I tried to google 'keep_bootcon'. It found several links to strange crashes related to this option. Maybe I was not patient enough but I did not find any page where this option was suggested and helped. I still think that the option makes some sense but only when it does not cause more breakages on its own. > If the new code can replace keep_bootcon, by all mean, go for it :-) keep_bootcon stays usable for most early consoles. We print a warning when an unusable console is disabled too early. Also there is a comment how to fix it. Best Regards, Petr