Re: userspace drivers

[Niels Möller]

Robert Millan <zeratul2@wanadoo.es> writes:

> well, from my tiny experience on writing a parallel port driver i can say
> that userspace drivers for GNU are very portable. The only system resources
> one needs (besides Hurd's fs libraries of course) is a working ioperm(), which
> is a portable function, and a way to wait for interrupts, ala
> intwait(unsigned short), which should be portable too.

You make it sound easy. That's nice.

Thinking about L4, I have no idea how ioperm should work, but intwait
should be fairly easy to implement, it just needs to wait for a
message from the kernel.

Besides functions like ioperm and intwait, I guess it would be nice
with some other more frameworkish things, like managing who can and
will serve each interrupt, but you don't need any of that until there
are a dozen or so of different drivers that need to cooperate, so that
can be an independent project.

> is such work welcome then? i mean, if i write a decent driver will it be
> included in the Hurd now or in a later term?

To me, it sounds like what you're doing will be useful both in the
shorter term (getting some more drivers), and as a way to get
experience in user level drivers, which will be needed when designing
whatever libraries and frameworks will be needed with L4.

As a final question, are there any parts of the oskit that are useful
for your driver?

/Niels