From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992793AbXDDJsQ (ORCPT ); Wed, 4 Apr 2007 05:48:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992794AbXDDJsQ (ORCPT ); Wed, 4 Apr 2007 05:48:16 -0400 Received: from adicia.telenet-ops.be ([195.130.132.56]:34560 "EHLO adicia.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992793AbXDDJsP (ORCPT ); Wed, 4 Apr 2007 05:48:15 -0400 Date: Wed, 4 Apr 2007 11:48:11 +0200 (CEST) From: Geert Uytterhoeven To: Russell King Cc: Brad Boyer , Paul Mackerras , David Woodhouse , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org Subject: Re: [PATCH] Stop pmac_zilog from abusing 8250's device numbers. In-Reply-To: <20070404085159.GB13134@flint.arm.linux.org.uk> Message-ID: References: <1175610345.2665.15.camel@shinybook.infradead.org> <17938.57292.870224.132415@cargo.ozlabs.ibm.com> <1175642916.10567.24.camel@shinybook.infradead.org> <20070403212928.GA12951@cynthia.pants.nu> <1175644642.10567.31.camel@shinybook.infradead.org> <20070403221002.GA13210@cynthia.pants.nu> <1175648051.10567.61.camel@shinybook.infradead.org> <20070403230908.GA13471@cynthia.pants.nu> <20070404085159.GB13134@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 4 Apr 2007, Russell King wrote: > On Tue, Apr 03, 2007 at 04:09:08PM -0700, Brad Boyer wrote: > > The availability of the specific chip in question is a red herring in > > my opinion. I do understand that 8250 compatible chips are very common > > and are the most likely serial chips to be used with Linux. However, I > > will point out that the define is TTY_MAJOR, not 8250_MAJOR. It seems > > to me that whoever named it was thinking in more generic terms. > > You're reading too much into the name. It's historical, and the reason > can still be seen in LANANA: > > 4 char TTY devices > 0 = /dev/tty0 Current virtual console > > 1 = /dev/tty1 First virtual console > ... > 63 = /dev/tty63 63rd virtual console > 64 = /dev/ttyS0 First UART serial port > ... > 255 = /dev/ttyS191 192nd UART serial port > > UART serial ports refer to 8250/16450/16550 series devices. > > When the drivers/char/serial.c driver was written, it was in the very > early days of Linux. I'd guess that the major/minor numbers were similar > to Minix, thereby allowing a minixfs to be used as the initial filesystem > type. > > Anyway, as you can see, defining chardev major 4 to be "8250_MAJOR" would > also be a misnomer because it's used for the virtual consoles, and it's > _that_ use for which it (probably) was called TTY_MAJOR. > > (Note that in the very early days, this major also got used for PTY > devices. Since then they've moved to major 2/3 and then we got Unix98 > PTY support.) Oh, and I always thought PTYs were moved to free up more minors for our zillions of serial ports... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds