Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Jul 2002 18:16:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Jul 2002 18:16:43 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:54280 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Mon, 29 Jul 2002 18:16:10 -0400 Date: Mon, 29 Jul 2002 23:19:27 +0100 From: Matthew Wilcox To: Russell King Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.linuxppc.org Subject: Re: [parisc-linux] 3 Serial issues up for discussion (was: Re: Serial core problems on embedded PPC) Message-ID: <20020729231927.D3317@parcelfarce.linux.theplanet.co.uk> References: <20020729040824.GA2351@zax> <20020729100009.A23843@flint.arm.linux.org.uk> <20020729144408.GA11206@opus.bloom.county> <20020729181702.E25451@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20020729181702.E25451@flint.arm.linux.org.uk>; from rmk@arm.linux.org.uk on Mon, Jul 29, 2002 at 06:17:02PM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2766 Lines: 53 On Mon, Jul 29, 2002 at 06:17:02PM +0100, Russell King wrote: > 3. /dev/ttyS*, /dev/ttySA*, /dev/ttyCL*, /dev/ttyAM*, etc > --------------------------------------------------------- > > All the above are serial ports of various types. It has been expressed > several times that people would like to see all of them appear as > /dev/ttyS* (indeed, there was an, erm, rather heated discussion about > it a couple of years ago.) I'm going to be neutral on this point > here. I'm not. All the issues you mention below go away if we make the rule that _all_ serial ports are /dev/ttyS*. Userspace can have symlinks to ease the transition if necessary. > c. People with many serial ports. We _could_ change the device number > allocations such that ttyS gobbles up the ttySA, ttyCL, ttyAM, etc > device numbers so we end up with the same number of port slots > available for those with many many serial ports in their machines. Yep, there really are people with >256 serial ports. It'd be nice to support them. Does anything care about the mapping from device name to char minor? I suspect the MAKEDEV maintainer will come and squash me if i suggest moving the mapping for the first 192 serial devices, but we should be able to reclaim: Chase serial card (major 17/18), the Cyclades (major 19/20), Digiboard (major 22/23), Stallion (major 24/25), Specialix (32/33), isdn4linux (43/44), Comtrol (46/47), SDL RISCom (48/49), Hayes (57/58), Computone (71/72), Specialix (75/76), PAM (78/79), Comtrol VS (105/106), ISI (112/113), Technology Concepts (148/149), Specialix RIO (154/155/156/157), Chase Research (164/165), ACM (166/167), Moxa (172/173), SmartIO (174/175), USB (188/189), Low-density misc serial ports (204/205), userspace (208/209) BlueTooth (216/217), A2232 (224/225) ... holy crap, that's a lot of char dev space ;-) 52 majors.. think what those must be worth on the open market ;-) My only real objection (and it's a problem we have at the moment!) is that serial ports then become like ethernet interfaces. Add or remove a card and everything changes number. Somehow we already survive with this. I was very careful when adding a new SIIG 4-port serial card to my console server the other day to notice which card was first in PCI bus scan order and make sure all my existing machines were hooked up to that one. The solution to this has to be to name devices by PCI bus ID, but this is an argument for an entirely different thread ;-) -- Revolutions do not require corporate support. - 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/