A problem has arisen in the USB device framework that
I'm working on:

USB device can be plugged and unplugged on the fly.
Doing that is not a problem, but the device probing
and attachment can take quite some time (several
hundred milliseconds) so it cannot be do in an interrupt
routine.  They way I'm doing it now is to have a demon
that does the necessary system calls to do the device
exploration.

This works well, except for one thing.  If you have 
a USB keyboard and boot in single user mode no keyboard
will be found since the exploration demon is not running.

I can see two solutions, none of which appeal to me:
1) Make an exploration pass during normal device probe
   and attachment.  I dislike this because it would mean
   operating the USB controller without the interrupts
   on, and that would be painful.
2) Make the USB exploration demon "magic" so that it is
   always running, even in single user mode.  Well, this
   is obviously unappealing.

Any suggestions?

        -- Lennart