From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932780AbcG1Hpl (ORCPT ); Thu, 28 Jul 2016 03:45:41 -0400 Received: from mout.kundenserver.de ([212.227.126.134]:61716 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753258AbcG1Hpc (ORCPT ); Thu, 28 Jul 2016 03:45:32 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Masahiro Yamada , Peter Hurley , Greg Kroah-Hartman , Linux Kernel Mailing List , Rob Herring , linux-serial@vger.kernel.org Subject: Re: debug tip after earlycon is closed? Date: Thu, 28 Jul 2016 09:44:53 +0200 Message-ID: <7034241.kLArk8ex69@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-28-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: References: <3860396.RT1mlU0LAT@wuerfel> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:+SXqvH32MqiLoMgKGHmtJBb0VsdmJcz5L1GLnk2rak7bt9Fr1yG gMBiSV+Yj/xZ2pwsrYBOmvZkpoyDCfJUXgK2j+l2KqyaVHeQNxTHEzOGgOdLCKZ+ArSo29b gXJzx8rJRrsXF5cXhsIHEGJ+zZI3AgtYOZH7zJP6bba6rUfo3kGJh46I90K1peTQorAzobL 3nZmCLulmBK2qHz6Y8ehg== X-UI-Out-Filterresults: notjunk:1;V01:K0:OjQZxFeI8U0=:U3MPRnOGsfmFZl5iBn0FJN mSQdjnJNutRBb8o+rlCYSWTuLoQymKtay8omUO4GDdv18xVS0AM4Oc+S4uQuFVByoOHvh4KSq XH/8EUkKt1nDSP9awYNWrTLnojnWFcKSRLFTOrIdGen5KoCppBi2XYACOfrQhISUg9hvL0Eiy EEyL71MRuKKA9VOb/YifwcMap9xR0vjn32cEuYOJToR+gm610eb3kCtjv7OIuzE85A4x1vGWW sYeYXj7jHvR7gNIaR6PtAXW/D/j2DT2PRSh6VJ6rZL2wl759EWFC4tBYShZ9IZGW0ngS1+JO4 eipSq1IY6+C+t4ZWse1AOZP1j4Maqi3W9mJw5LegZOC+zDgpSTGGUeN+uWRz0QIynbSlUu9T2 jO5tXvGMrsLjSTJynE6wri4hAREg3jFZRLBWUHUzxV1xRkmZJ+pLA+T0nEnX9zXiyWoxL3jUy AZx00y09Rw2G8ZXEEYlJXCEkwceJ4YA9h3VI4Zt56NlbxCDttsTLPWb7Bv7JwBM1KaMTl5xix H14hNivZc2CF9BHmjlML5DbQ8BSlr4dlS10Hy4NDFzgh+cmCGwhVCL2M2d2FyEh+xX/S6CKYR GCh4d+sitp6kEvORSvsmCThTswvEMW1nf1KckrmcnPh1PV1q4wnh2Ns+cqWOJFZaNsROv87ka 9zf0y4DMf3aV2+Hyvy0HpKNC0//r7+EJzoazCvUz5LO/dRz57PHIsuNvJLOPfbVdsh2agRLoq qVHTbK5G3NnV82R6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, July 28, 2016 11:08:13 AM CEST Masahiro Yamada wrote: > Hi Arnd, > > > 2016-07-27 16:32 GMT+09:00 Arnd Bergmann : > > On Wednesday, July 27, 2016 10:23:09 AM CEST Masahiro Yamada wrote: > >> [ 0.000004] sched_clock: 56 bits at 50MHz, resolution 20ns, wraps > >> every 4398046511100ns > >> [ 0.008254] Console: colour dummy device 80x25 > >> [ 0.012700] console [tty0] enabled > >> [ 0.016110] bootconsole [uniphier0] disabled > > > > I assume that the original console is on a uart, while the new console > > appears to be on the framebuffer. Maybe you have no screen attached? > > > > > I use 8250-compat serial console for both. > > > The following is the full boot log when success. > > > I am not sure about: > [ 0.000141] Console: colour dummy device 80x25 > [ 0.000550] console [tty0] enabled > > > > This is the UART console I am really using. > [ 0.234743] 54006800.serial: ttyS0 at MMIO 0x54006800 (irq = 6, > base_baud = 3676470) is a 16550A > [ 0.994393] console [ttyS0] enabled I think the problem is that you have three consoles: - the boot console that stays active until a real console comes up - the framebuffer console that is initialized early and goes on to disable the bootconsole - the serial console that you are looking at but which doesn't get initialized until much later Clearly something is wrong in this setup and we don't want to disable the boot console before the serial console is up. I guess you could work around it by disabling the framebuffer console at compile time, or by having the serial console initialized earlier than the framebuffer, but I wonder if this is something that could use a more general solution. Arnd