Re: Adding PCMCIA support to the kernel tree -- developers needed.

[David Brownell <david-b@pacbell.net>]

From Oliver:

> I have thought more about it.
> You cannot simply wait. In fact you need to cancel those requests to user
> space. If you simply replay the sequence of events you have scripts acting on
> device nodes that have already been reused. Simple waiting is even worse.
> You'd loose the defined order of events. The result wouldn't even be
> deterministic.

When I thought about this last year, my conclusion was that it SHOULD
be OK to have multiple event orderings so long as all were correctly
serialized with respect to essential criteria.  Just as if they were database
transactions that didn't interfere with each other.  The configuration of a
GNU/Linux operating environment is a transactable problem, and users
have no business caring which hotplug action is handled first ... so long
as each one is handled correctly.


> On the activation of user space hotplugging support plugging events must be
> faked and must reflect current hardware. Probably user space should be
> notified of the fact that these devices may already be in use.

I suspect there are solutions that don't involve faking, but there'd be a
price in extra complexity.  Userspace SHOULD be able to see if the
device has a driver bound to it ... I'm not quite so sure about "in use",
which I usually think of as meaning "opened".

- Dave



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