Date: Sat, 4 Oct 2003 10:35:55 +0200 From: Bernd Walter <ticso@cicely12.cicely.de> To: "Christoph P. Kukulies" <kuku@physik.rwth-aachen.de> Cc: ticso@cicely.de Subject: Re: total hang when cu -l /dev/cuaa0 Message-ID: <20031004083554.GP886@cicely12.cicely.de> In-Reply-To: <20031004082548.GA9168@gilberto.physik.rwth-aachen.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>
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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
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