In message <9512090904.AA00970@bunya.awadi> you write: 
> According to Travis Hassloch:
> The granuality of the I/O permission map is on a byte level.  Each bit

> I think a system call would be the best way - not sure if you want to
> make the caller specify the entire permission map they want or have a

Anyone feel strongly either way about adding this?
I think allowing user-level procs to do I/O would be way cool, allowing neat
things like developing "device drivers" while the system is running - using
normal tools.  E.G. an audio server that talks to other procs via IPC.  This
leaves the OS developers to concentrate on more important things, and
simplifies dd development.  Of course, it's not exactly clear how to handle
interrupts.  Guess you'd have to have some kind of reservation system, like
in Exo-kernels.

Does Mach support user-space device drivers?