Re: PCI driver in userspace

[Stelian Pop <stelian.pop@fr.alcove.com>]

On Tue, Feb 26, 2002 at 07:52:39PM -0500, Pete Zaitcev wrote:

[Interrupts in userspace...]

> >> Although I dont know if this is a good idea in the first place.
> > 
> > I think it depends on the interrupt frequency, and other things.
> > 
> This is why purely
> user level interrupts are IMPOSSIBLE (regardless of interrupt
> frequency).
[...]
> 2. Write a small driver that deactivates interrupts and queues
> interrupt events (with SIGIO and some other means).

This is what I meant too, and I was talking about the interrupt 
frequency because if there are too many IT, continuous polling might
be more efficient than interrupt handling with the kernel driver + 
userspace signal sending.

> Very many people are psychologically afraid of drivers
> (even though it's quite simple), and they wank those userspace
> approaches, until they hit some brick wall (interrupts being
> most common). By that time they invest so much into their code
> that they are loth to abandon broken userland drivers and
> start grappling about desperately for a way out.

It depends on the driver. If moving _all_ the driver in kernelspace
involves putting policy and other stuff into the kernel, then no. 

Stelian.
-- 
Stelian Pop <stelian.pop@fr.alcove.com>
Alcove - http://www.alcove.com