Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756814AbZDVVKk (ORCPT ); Wed, 22 Apr 2009 17:10:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754089AbZDVVK2 (ORCPT ); Wed, 22 Apr 2009 17:10:28 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:47358 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752596AbZDVVK1 (ORCPT ); Wed, 22 Apr 2009 17:10:27 -0400 Date: Wed, 22 Apr 2009 22:08:53 +0100 From: Alan Cox To: David VomLehn Cc: Alan Stern , Jamie Lokier , Ingo Molnar , Arjan van de Ven , "H. Peter Anvin" , Thomas Gleixner , Linus Torvalds , Linux Kernel Mailing List , Linux USB Mailing List , Linux Embedded Mailing List , Andrew Morton Subject: Re: Wait for console to become available, v3.2 Message-ID: <20090422220853.0af12ece@lxorguk.ukuu.org.uk> In-Reply-To: <20090422205427.GA28435@cuplxvomd02.corp.sa.net> References: <20090421230849.GA29555@cuplxvomd02.corp.sa.net> <20090422205427.GA28435@cuplxvomd02.corp.sa.net> X-Mailer: Claws Mail 3.7.0 (GTK+ 2.14.7; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1633 Lines: 33 > Alright, I know you (Alan (Stern)) know about USB. I think someone else > mentioned Firewire. What other hotpluggable buses do we need to worry about > and how can we get them interested? In theory any console can be hot pluggable - PCI-X hotplug video cards, hotplug serial ports. In fact right now bad things occur if you hot-unplug consoles. > 2. All devices have been probed > If we exit for reason 2, it means that no such device is present, > and we go on to the do the appropriate thing for that device class. USB has no notion of #2 really > Yes, I think we absolutely exclude devices plugged in after boot. I think such > usage, if it needs to be supported, can be handled with hot plugging. I'm a > little squishy on whether we might to be able to hot plug USB consoles as I > have a request to support this, but I think it's a separate issue from > supporting hot pluggable boot devices and I'm not worrying about it now. This still assumes you can tell the difference, but USB in particular is rather like undergraduate students - they turn up when they feel like it at some point after they get kicked into life. I don't think that is a big problem because our bus model is basically that all devices are discovered asynchronously (increasingly so with Arjan's speed up patches). A console model therefore has to deal with console addition and removal being dynamic. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/