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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 2D9C8C4360F for ; Fri, 5 Apr 2019 12:33:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3162217D4 for ; Fri, 5 Apr 2019 12:33:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731077AbfDEMdU (ORCPT ); Fri, 5 Apr 2019 08:33:20 -0400 Received: from mout.kundenserver.de ([212.227.126.131]:58785 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726663AbfDEMdU (ORCPT ); Fri, 5 Apr 2019 08:33:20 -0400 Received: from [192.168.1.110] ([95.114.101.225]) by mrelayeu.kundenserver.de (mreue012 [212.227.15.167]) with ESMTPSA (Nemesis) id 1M8C8J-1hFyf20I3H-005HF2; Fri, 05 Apr 2019 14:32:43 +0200 Subject: Re: [PATCH] tty: Add NULL TTY driver To: Vincent Whitchurch Cc: Greg KH , jslaby@suse.com, linux-kernel@vger.kernel.org References: <20190403113327.3628-1-vincent.whitchurch@axis.com> <20190403131213.GA4246@kroah.com> <20190403141109.3mdmqbt3mjxrie6k@axis.com> <20190405090043.vnsftwpdm56cx2hr@axis.com> From: "Enrico Weigelt, metux IT consult" Organization: metux IT consult Message-ID: Date: Fri, 5 Apr 2019 14:32:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190405090043.vnsftwpdm56cx2hr@axis.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:kycUXfgYd7q21EdW2ZVJXFslpqyKKrR9n7N3uQ3jC0Aq4ohFfkg C5v9QmVq0zt8nkoalB1T7tiXQyScNTYqesXpKA6so7XOnLIiXCL82yADBhuEhk85/8Q6MOo dCB5I3VED7pkitSnVS+NHTkobhr2+DjQ4Y0fFgySP91hk5Jjg3LedO+X2LEG81IAgm62kk9 hb2xlujnfRcExGGbbQ3JA== X-UI-Out-Filterresults: notjunk:1;V03:K0:tb7VGjqjxU8=:oXUBqTQaAvYC0j8aRk3+EZ jKJERXb/ZBf1+xWRSPdcmBf+eCfS/d2EoYg/NnPshE+R6/J06J6qdbCFqM8RA5LljOLY02vC3 EjNQdGc0L3ePPt1rggjbfcEk6FV0/W5pT6DQABOsM8HDcTYopxfdM6JRtqNnPzLGbPSubTvra bl65L6baZYEBDhpez/fbfRclN8zN/mrnOyI72WH1dTOSU+roPKAmpQcHhGt17nq6h+lDa6lWM VlNo/LFCOXZ2uywMvqVhlcXm/3Acs9RHpaI1UZMx6RBXeC6f24Ef19qp1NXlJWVIgqmyWQ5+N 27CfN2rSxNh66HTRUtQURRsecIxscyCLGq6T/JJAuH9xkbsMHkPQkJYe/DAeVDptiNXknV2zV LceTTzubDe+FVzSfzLjeLzSEPHxhl3wVP0Lr+x4AmRU6e7EmongRYp5mvryvencXWjO8nVckW amkKTTPiAnNL/DVYbG0Z5Y5JDfhxjhzVxVMQeXAWs7S8gJhXufYECgbjWIMPjYfpRGRbLbnWe hjAjkGdMLKCiLlCAcCKbovTP5GcfMc47NioZvIUtjddsMPyEhs999fQH1TqXmkKUWfZq0IuDE AuP2ldTn5NBGWjvAEmZL4fWq+RwPxOXbjXe+Uf7I8cnaFRVADQLu+42J3QwILgwnU40C00JQk 7pR+K86X/IUlrO3NV2/JB/rXIf+wO0hGVGV0N6tZkm4N8C7Hcy6ZZMu9HAkZV8JTYZ8p4BlyX mT7HHbTkKEqSUEkeEfjoB1VH/MPul9wVDxiAyC2EDnPCBMhUljt3kAOdF8Y= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.04.19 11:00, Vincent Whitchurch wrote: > On Fri, Apr 05, 2019 at 10:39:43AM +0200, Enrico Weigelt, metux IT consult wrote: >> On 03.04.19 16:11, Vincent Whitchurch wrote: >> >>> Especially on embedded systems, it would be convenient to have a simple >>> way to disable the console (both for kernel and userspace) on a system >>> which normally uses it, to free up the UART for other things. >> >> Just symlinking to /dev/null does not work ? > > No, /dev/null does not support the TTY ioctls. hmm, wo (which programs) do you need, that really need them ? >> OTOH, if you're introducing a dummy console, wouldn't a ringbuffer that, >> can be read out later, a better option ? > > There is already a ttyprintk driver in mainline to send these messages > to the printk ring buffer if one is actually intrested in what is > written to the console. There's no option to enable it via console= in > mainline but I have a patch for that too. Great. IMHO, that would be the better way. --mtx -- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287