From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161055AbWFJXo5 (ORCPT ); Sat, 10 Jun 2006 19:44:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161057AbWFJXo5 (ORCPT ); Sat, 10 Jun 2006 19:44:57 -0400 Received: from nz-out-0102.google.com ([64.233.162.203]:57030 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S1161055AbWFJXo5 (ORCPT ); Sat, 10 Jun 2006 19:44:57 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=pOEqB/aYk4WAb2qxMgGk16gRaj2iA6GEl+jmG6bvzJsZuNWGkKGjq0qqGy5KGtG/HITnNPl05LL+sveUEFUYxftmsYpXYbelEEJsn26/Sx9TAFQvlXCW+xCm4edSlHZKGy5sAgXUCXUO34CqEQk2doqJR7Tu6ZGnBYBAPApZJN4= Message-ID: <9e4733910606101644j79b3d8a5ud7431564f4f42c7f@mail.gmail.com> Date: Sat, 10 Jun 2006 19:44:56 -0400 From: "Jon Smirl" To: "Antonino A. Daplas" Subject: Re: [PATCH 5/5] VT binding: Add new doc file describing the feature Cc: "Andrew Morton" , "Linux Fbdev development list" , "Linux Kernel Development" , "Greg KH" In-Reply-To: <448B38F8.2000402@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <44893407.4020507@gmail.com> <9e4733910606092253n7fe4e074xe54eaec0fe4149f3@mail.gmail.com> <448AC8BE.7090202@gmail.com> <9e4733910606100916r74615af8i34d37f323414034c@mail.gmail.com> <448B38F8.2000402@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 6/10/06, Antonino A. Daplas wrote: > > I may be looking at the problem a little differently. I see the > > drivers like fb, vga, etc as registering with the console and saying > > they are capable of providing console services. I then see the console > > system as opening one of the registered devices. A driver is free to > > register/unregister whenever it wants to as long as it isn't open by > > the console system. Console can only open one driver at a time. > > No, this isn't true. You can have multiple console drivers active, > that's why you have a first and last parameter in take_over_console(). > Thus at boot time, the system driver will take consoles 0 - 63. > Later on when a driver loads, it can take over consoles 0 - 7, leaving > consoles 8 - 63 to the system driver. > > To put it another way, console drivers can register for consoles 0 - 63, > but the user may choose to use it only for consoles 0 - 7. > > This is another reason for the system driver, it makes the unbinding > behavior predictable. Without a system driver, guessing which driver > replaces the just unbound one may become just a tad bit confusing for > the typical user. I find the whole console/tty layer to be quite confusing to talk about. I am mixing up console as in where printk goes and console the video card login device. The part about making everything equal was directed towards the printk output device. I see now that you can have tty0-7 assigned to a different console driver than tty8-63. Why do I want to do this? Why do we need 64 predefined tty devices? Googling around the only example I could find was someone with a VGA card and a Hercules card. They setup 8 consoles on each card. > > Over time it would nice if these all merged to a single > > interchangeable interface. I would really like to be able to > > dynamically switch to serial/net while debugging a video driver. Is > > there some fundamental reason why these can't be merged? > > It's already possible to redirect the system messages to two different > console classes, ie with the boot parameter: > > console=tty0,ttyS0 /* direct output to VT and serial console */ > > And you can already choose the console you want by adjusting /etc/inittab. How can I change where printk are going at run-time? I didn't know you could do that. -- Jon Smirl jonsmirl@gmail.com