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Date:      Fri, 22 Jan 1999 11:41:58 -0800
From:      Mike Smith <mike@smith.net.au>
To:        Nate Williams <nate@mt.sri.com>
Cc:        Mike Smith <mike@smith.net.au>, "Gary T. Corcoran" <garycor@home.com>, mobile@FreeBSD.ORG
Subject:   Re: Reclaiming irqs for unsupported PCI hardware? 
Message-ID:  <199901221941.LAA00993@dingo.cdrom.com>
In-Reply-To: Your message of "Fri, 22 Jan 1999 12:40:04 MST." <199901221940.MAA22323@mt.sri.com> 

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> > > 
> > > Sure it does.  IRQ's are no longer generated on that piece of hardware,
> > > but it's possible that the IRQ routine was in the middle of processing
> > > the previous (valid) IRQ that was generated 'just prior' to the removal.
> > 
> > Uh, it's also possible for the removal itself to generate an interrupt 
> > - I had this 100% repeatable on the Sharp I used to use.
> 
> Right, but this does not work reliably on all PCIC controllers.  It
> works on mine, but I know a number of controllers it does not work on
> (for whatever reason).

Sorry, you're missing my point - the removal causes a *card* interrupt, 
not a PCIC interrupt.

> > > > In other words, just make sure mobile users know they _must_
> > > > shutdown a card before removing it, and forget about trying to handle
> > > > stupid (or accidental) user actions.
> > > 
> > > The use of the IRQ makes it less painful *IF* the user yanks their
> > > card.  Is it worth making it easier?  I don't know.
> > 
> > That's it in a nutshell.
> 
> You got it.  If we've got the IRQ, we *can* make it safer.  But, it
> doesn't work reliably on some hardware, and it 'wastes' an interrupt
> that might otherwise be used for something else.  (I'm using the term
> 'waste' loosely here, since I think it makes the system more robust..)

Understood.  Hmm.
-- 
\\  Sometimes you're ahead,       \\  Mike Smith
\\  sometimes you're behind.      \\  mike@smith.net.au
\\  The race is long, and in the  \\  msmith@freebsd.org
\\  end it's only with yourself.  \\  msmith@cdrom.com



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