From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030225AbWFJEh7 (ORCPT ); Sat, 10 Jun 2006 00:37:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030256AbWFJEh7 (ORCPT ); Sat, 10 Jun 2006 00:37:59 -0400 Received: from mail.kroah.org ([69.55.234.183]:44778 "EHLO perch.kroah.org") by vger.kernel.org with ESMTP id S1030225AbWFJEh7 (ORCPT ); Sat, 10 Jun 2006 00:37:59 -0400 Date: Fri, 9 Jun 2006 21:37:52 -0700 From: Greg KH To: "Antonino A. Daplas" Cc: Andrew Morton , Linux Fbdev development list , Linux Kernel Development Subject: Re: [PATCH 2/5] VT binding: Add sysfs support Message-ID: <20060610043752.GA20088@suse.de> References: <448933D7.6040301@gmail.com> <20060609220803.GB7636@suse.de> <448A147A.3030108@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <448A147A.3030108@gmail.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 10, 2006 at 08:38:18AM +0800, Antonino A. Daplas wrote: > Greg KH wrote: > > On Fri, Jun 09, 2006 at 04:39:51PM +0800, Antonino A. Daplas wrote: > >> Add sysfs attributes for binding and unbinding VT console drivers. The > >> attributes are located in /sys/class/tty/console and are namely: > >> > >> A. backend - list registered drivers in the following format: > >> > >> "I C: Description" > > > > No, this violates the "one value per file" issue with sysfs. How do you > > know you will not overflow the buffer passed to you? > > I was wondering about this. I just want a way to show what are the currently > loaded drivers, so it's a read-only attribute. It's using snprintf (though > I haven't added a check for possible overflows, should be a 2-liner). Maximum > number of lines is 16, and there are examples of this rule-breakage in the > current sysfs tree. > > /sys/class/usb_host/usb_hostx/device/pools Ah, thanks for pointing this out. Those files should go to debugfs, they do NOT belong in sysfs at all. > Yes, none are valid excuses. Anyway, what would be the best way? I was > considering creating another class for vt_console, but that would entail > the creation of a new device major number just for this. No, you don't need a major to create a new class in sysfs at all. Look at usb_host for an example of that :) And even if you did, we have loads of free major numbers now, it's not a big deal to get a new one. I vote for this, it would make things much easier. > >> Where: I = ID number of the driver > >> C = status of the driver which can be: > >> > >> S = system driver > >> B = bound modular driver > >> U = unbound modular driver > >> > >> Description - text description of the driver > >> > >> B. bind - binds a driver to the console layer > >> > >> echo > /sys/class/tty/console/bind > >> > >> C. unbind - unbinds a driver from the console layer > >> > >> echo > /sys/class/tty/console/unbind > >> > >> The tty layer does nothing to these attributes except create them and punt all > >> requests to the VT layer. > > > > Why is this needed? What is wrong with the current scheme of binding > > ttys to the console? > > > > The binding part, maybe none, but that's still debatable. It's the unbinding > feature that people are requesting. Note the longish threads on "the future > of graphics subsystem". It would also ease the life of console driver > developers, and it would stop people from pestering me on why they cannot unload > their beloved framebuffer console and drivers and go back to VGA console. Ok, I also read the 0/5 in this series which describes this in detail, sorry for not seeing that (hint, cc: everyone on the series that one too, so they get a bit of detail in the future.) thanks, greg k-h