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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 6C89EC433FF for ; Sat, 3 Aug 2019 13:55:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FDF521726 for ; Sat, 3 Aug 2019 13:55:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564840543; bh=4UmoDoYVdrWFjZ2tni2H5YosvR67LNdT3rchHwiQHEc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=fBL03iF/YbkjybSa0eaEURfqdnIUkiIDRBv5/hkF3bOC9RfmL8at2SR4qRLcOmNRv SAcAaoDMMtwJN8w/qh5c1aM8PjMPOR7xvDB+uDKdEqsrfT1iBad+Mo2DaWK4KmU2SY 117C85vGea54yFzZTtNaYfNNOo9k5JPGwbvXmkb0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390985AbfHCNzl (ORCPT ); Sat, 3 Aug 2019 09:55:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:44976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726340AbfHCNzk (ORCPT ); Sat, 3 Aug 2019 09:55:40 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A3EBA2166E; Sat, 3 Aug 2019 13:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564840540; bh=4UmoDoYVdrWFjZ2tni2H5YosvR67LNdT3rchHwiQHEc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DSjAwHm8J2w5ILHJh27mU4VqH+sajLtPJ20zxB9s76nP2Ha6J94z3zv0xJS/WtJ5J kukH2u6JKnBx0MhQQg+ExnlhH0JgM6jJ4GXbhbqPWgiZEMNQ0M/5LSBldpxxI3YqZa EhReTiKjhnDzuG+ZTDUzuJMRzBads4uKtCNU4YGc= Date: Sat, 3 Aug 2019 15:55:37 +0200 From: Greg Kroah-Hartman To: Adam Borowski Cc: Paul Menzel , linux-serial@vger.kernel.org, Linux Kernel Mailing List , Donald Buczek Subject: Re: Device to write to all (serial) consoles Message-ID: <20190803135537.GA1743@kroah.com> References: <32c2d26f-ec4a-b9a6-b42c-07b27f99ea28@molgen.mpg.de> <20190802160243.GA15484@kroah.com> <20190803132323.GB6703@angband.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190803132323.GB6703@angband.pl> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 03, 2019 at 03:23:23PM +0200, Adam Borowski wrote: > On Fri, Aug 02, 2019 at 09:59:06PM +0200, Paul Menzel wrote: > > On 02.08.19 18:02, Greg Kroah-Hartman wrote: > > > On Fri, Aug 02, 2019 at 03:23:08PM +0200, Paul Menzel wrote: > > > > On a lot of devices, like servers, you have more than one serial console, > > > > and you do not always know, how they are numbered. Therefore, we start a > > > > console on ttyS0 and ttyS1. > > > > Because the cable is always connected to the port on the back side, and > > sometimes the port in the front has ID 0, and the one in the back 1, and > > other times vice versa. We do not want to track that, and it would be > > convenient to just write to both ports. > > Sounds like an XY problem then: what you want is not writing to all ports, > but to have the port assignments stable (see also: disk device reordering). You can get that information from the symlinks in /dev/serial/ which udev creates.