total hang when cu -l /dev/cuaa0

Bernd Walter ticso at
Sat Oct 4 01:36:16 PDT 2003

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      
ticso at                                  info at

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