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From: Terry Lambert <terry@lambert.org>
Message-Id: <199611032100.OAA03152@phaeton.artisoft.com>
Subject: Re: ed0 timeouts
To: smp@csn.net (Steve Passe)
Date: Sun, 3 Nov 1996 14:00:34 -0700 (MST)
Cc: dg@Root.COM, hackers@freefall.freebsd.org, smp@freefall.freebsd.org,
        bde@zeta.org.au
In-Reply-To: <199611030900.CAA25770@clem.systemsix.com> from "Steve Passe" at Nov 3, 96 02:00:44 am
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> >   Yes, you can get another interrupt while servicing one. The driver loops
> >until all interrupts are serviced, but there would be a window between when it
> >thinks there are no more interrupts to service and returning to vector.s to
> >unmask the interrupts. This window will exist in all ISA drivers.
> 
> bummer...
> 
> Intel says:
> 
> It is strongly recommended that first 82489 (ie APIC) should be unmasked
> and then the device interrupt should be enabled.  By this sequence software
> can ensure that always an edge will occur at the APIC input only after
> the interrupt is unmasked.

Or: "Don't ack the thing until fater it's unmasked".


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.