Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751179AbdCQLDn (ORCPT ); Fri, 17 Mar 2017 07:03:43 -0400 Received: from mail-lf0-f66.google.com ([209.85.215.66]:34377 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbdCQLDl (ORCPT ); Fri, 17 Mar 2017 07:03:41 -0400 Subject: Re: Does braille console work? To: Greg Kroah-Hartman References: <1bb67bee-b8f9-2835-725a-f36fda085216@linaro.org> <20170317005355.xwym3zpamym3rwp6@var.youpi.perso.aquilenet.fr> From: Aleksey Makarov Cc: Samuel Thibault , Aleksey Makarov , linux-serial@vger.kernel.org, Petr Mladek , Steven Rostedt , Joe Perches , linux-kernel@vger.kernel.org Message-ID: <6657242f-e4a9-f142-a6eb-f0c07a7d04f3@gmail.com> Date: Fri, 17 Mar 2017 12:00:02 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170317005355.xwym3zpamym3rwp6@var.youpi.perso.aquilenet.fr> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1941 Lines: 56 On 03/17/2017 03:53 AM, Samuel Thibault wrote: > Hello, > > Aleksey Makarov, on jeu. 16 mars 2017 17:02:53 +0300, wrote: >> There can be 3 outcomes from this function: >> 1) it returns NULL and does not set brl_options >> 2) it returns NULL and set the variable pointed by str to NULL >> 3) it returns non-NULL > > Uh, that's odd indeed, the intent was that it'd return an error code > only. > >> To register a braille console (i. e. to call __add_preferred_console() >> with non-NULL brl_options) function _braille_console_setup() should >> return NULL and initialize brl_options. > > return 0 (as in no error), actually, in the intent. > >> 1) in this case brl_options is NULL and non-braille console is registered >> 2) kernel produces oops later in console_setup(). I reproduced it >> passing "console=brl=aaa" parameter to kernel, see below. >> 3) no console is registered >> >> So braille console registration should not work. What do I miss? > > Nothing, the code transformation was broken :/ So the kernel contains seemingly unmaintained code that does not work for at least 3 years. Its parts in printk.c considerably complicate code support. >> So it looks like braille console has not been used for more than 3 years. >> Should we remote it? > > Please, no :) > > It is indeed not often useful, since one would usually use a userland > daemon to access the system, but when one's system does not boot > properly or something similar, it's useful to have the braille > console. That's just very not often useful. Why should we keep the code which does not work? And which is used more than 3 years ago and usage requires patching. I think removing it is a good idea Thank you Aleksey Makarov > Samuel > -- > To unsubscribe from this list: send the line "unsubscribe linux-serial" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >