Upcall handler

Peter Naulls peter at chocky.org
Mon Dec 17 04:40:05 PST 2001


In message <m3heqqvyog.fsf at nick.ws.noc.dsvr.net>
          Nick Burrett <nick at dsvr.net> wrote:

> Peter Naulls <peter at chocky.org> writes:
> 
> > Reply from Kevin Bracey:
> > 
> > "There were added in RISC OS 3 a number of buffer UpCalls that are
> > actually called from interrupt routines. This is a Bad Thing(TM) - they
> > should have been events. As a result, an UpCall handler may be being
> > called from interrupts - I suggest you take care.
> > 
> > Apart from that, I can't think of any other reason why UpCalls are a bad
> > thing per se."
> 
> If we are in an interrupt, then do you think exiting the upcall handler
> without doing anything could be a suitable workaround.
> 
> We could perhaps exit the upcall handler early, if we are in an interrupt.

If I understand what you're saying correctly, then we've always exited
our upcall handler ASAP, if it's not for us.  i.e. not 256.
This doesn't really help though, as our handler simply might not be
paged in at the time when getting an upcall from buffer manager.   Hence
my module solution.

Peter

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 Peter Naulls - peter at chocky.org
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