From owner-freebsd-hackers@FreeBSD.ORG Sat Oct 4 01:36:16 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 06A2616A4B3 for ; Sat, 4 Oct 2003 01:36:16 -0700 (PDT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 64FF843FCB for ; Sat, 4 Oct 2003 01:36:10 -0700 (PDT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de (cicely5.cicely.de [IPv6:3ffe:400:8d0:301:200:92ff:fe9b:20e7]) (authenticated bits=0) h948a0Fs094392 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Sat, 4 Oct 2003 10:36:07 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [IPv6:3ffe:400:8d0:301::12]) by cicely5.cicely.de (8.12.10/8.12.10) with ESMTP id h948ZuWZ057435 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 4 Oct 2003 10:35:57 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.10/8.12.10) with ESMTP id h948Zu2u010680; Sat, 4 Oct 2003 10:35:56 +0200 (CEST) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.10/8.12.10/Submit) id h948Zu1R010679; Sat, 4 Oct 2003 10:35:56 +0200 (CEST) (envelope-from ticso) Date: Sat, 4 Oct 2003 10:35:55 +0200 From: Bernd Walter To: "Christoph P. Kukulies" Message-ID: <20031004083554.GP886@cicely12.cicely.de> References: <200310031821.h93ILSVI001295@www.kukulies.org> <20031003201507.GK886@cicely12.cicely.de> <20031003212334.GA2076@gilberto.physik.rwth-aachen.de> <20031003213628.GN886@cicely12.cicely.de> <20031004082548.GA9168@gilberto.physik.rwth-aachen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031004082548.GA9168@gilberto.physik.rwth-aachen.de> X-Operating-System: FreeBSD cicely12.cicely.de 5.1-CURRENT alpha User-Agent: Mutt/1.5.4i cc: "C. Kukulies" cc: hackers@freebsd.org cc: ticso@cicely.de Subject: Re: total hang when cu -l /dev/cuaa0 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Oct 2003 08:36:16 -0000 On Sat, Oct 04, 2003 at 10:25:48AM +0200, Christoph P. Kukulies wrote: > On Fri, Oct 03, 2003 at 11:36:29PM +0200, Bernd Walter wrote: > > You can't expect anything reliable from a device which is broken. > > The kernel already warned you that something seems to be questionable. > > In the same way you can't expect getting an IO error if someone cuts > > into your computer with a chainsaw - you may get one, but nobody can > > predict. > > A device disabled by the BIOS should not be accessible in any way > by the kernel. It's not broken nor has anyone cut the devices with a chainsaw. > I don't read dmesg before I try to open /dev/cuaa0. > > So an open on /dev/cuaa0 when sio is disabled in the BIOS should not result > in a bad hangup. That's my point. If it really is disabled then you would not have a /dev/cuaa0 to open and you would see a correct error when trying to do. The point is that the kernel sees partially disabled hardware. A device that is something between enabled and disabled cause unpredicable behavour - it's a completely undefined situation. The easiest way is to disable the device in the kernel too. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de