> -----Original Message-----
Samuel Tardieu [mailto:[EMAIL PROTECTED]] writes:
> Sent: Thursday, March 30, 2000 11:46 AM
> To: Eric Peterson
> Cc: '[EMAIL PROTECTED]'
> Subject: Re: Deferred procedure call available?
>
>
> >>>>> "Eric" == Eric Peterson <[EMAIL PROTECTED]> writes:
>
> Eric> Sometimes called "task queues" or "deferred callbacks", they
> Eric> allow an interrupt handler to schedule a (possibly predefined)
> Eric> function to be called outside the context of the interrupt.
>
> (not an answer, just a suggestion) Is there anything you cannot do
> with a userland program, that will be resumed by the interrupt
> handler? Doing this even gives you the possibility of choosing the
> priority of the deferred handler relative to other handler and regular
> processes (as eCos does).
Sam,
Thanks for the response. With regard to your suggestion (my
ignorance of
FreeBSD drivers certainly shows through here, but...):
1. I'm porting an existing driver, so am trying to keep its
basic
structure intact. I don't believe that a user-mode entity
has
access to the memory/device address space I need to get to.
2. I suspect that going from kernel to (even high priority)
user
mode entails a non-trivial performance penalty (somebody
please correct
me if not!)
One other approach I was thinking about was to have a sleeping
kernel thread
that I could wakeup when I needed to schedule a function to be
called.
I'm going to try out the timeout(9) routine that Mike Smith
suggested, looks like
just the ticket (thanks again, Mike).
Regards,
Eric
--
Eric Peterson WB6PYK
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