Yeah, I understand. Actually, my development OS options are Linux and DOS
(where I know I could just handle interrupts from userspace, because
everything is userspace :). Guess which one I chose ... ;)
> > > normally, a user-level process
> > > would just do a blocking read or ioctl, and the driver would sleep
> > > the process until an interrupt comes in.
> >
> > The problem with that is that you're assuming there is already a driver
> > for this specific device. I'm trying to write a HW test application that
>
> no, I'm making no such assumption. I'm stating that this could be done
> with a new driver that was completely generic: you'd tell it to register
> to handle a particular interrupt, then make some blocking call like
> read or ioctl. the driver simply catches the interrupt, and wakes you up.
> this is extremely simple, probably ~20 LOC. what's tricky is figuring out
> how to do it usefully, handling things like interrupt masking/ack, etc.
Yes. How to clear the interrupt is a especially interesting one, because:
- each device has its own way of clearing it (how would you define the
driver interface so that the application is able to tell, from
userspace, how to clear the interrupt, and it's general enough to work
with _any_ device??).
- you would have to clear it _before_ you actually service it, otherwise
you'll be stuck on the driver intr. handler and, thus, it'll be
impossible to service it from userspace. But since you haven't serviced
it, the interrupt would probably happen again, and then ... :)
> > does _not_ depend on a specific driver to work, an application that can
> > access the specific HW directly and test it. I already know how to access
> > MMIO, the PCI bus and such, but I don't know how to handle interrupts from
> > userspace.
> >
> > Suggestions ?!?!
>
> a dummy interrupt driver.
Let's say we have this driver. How should the application and the driver
interface ?? You've mentioned a blocking call. Could you give an example
of that for this particular (hypothetic) case ?? I've also heard of using
a task queue for that. Do you know anything about how to use it ?!?!
Thanks much for your comments so far.
Regards,
Ivan
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