Subject: Re: Interrupt, interrupt threads, continuations, and kernel lwps
To: None <tech-kern@netbsd.org>
From: Andrew Doran <ad@netbsd.org>
List: tech-kern
Date: 06/25/2007 13:51:37
On Thu, Jun 21, 2007 at 08:07:24AM +0100, David Laight wrote:

> On Wed, Jun 20, 2007 at 10:54:14PM +0100, Andrew Doran wrote:
> > What I mean is that from a hardware ISR that does not have thread context
> > (like at IPL_NET) it wouldn't be possible to call callout_reset() or similar
> > functions. That would need to be deferred to a soft interrupt or a kernel
> > thread.
> 
> Uggg...  wouldn't it be possible to be able to specify a PL level at
> which a callout function will run?
> That would allow such callouts to be used from WH interrupts.
> SPL locking the callout table shouldn't be a problem.

It will still need to be spinlocked as the clock interrupt wants to play
about with the callout tables. Specifying the priority level seems too
complicated. I'd rather that the callouts always ran with thread context.
 
Andrew