Date: Sun, 03 Nov 1996 15:10:33 -0700 From: Steve Passe <smp@csn.net> To: Terry Lambert <terry@lambert.org> Cc: dg@Root.COM, hackers@freefall.freebsd.org, smp@freefall.freebsd.org, bde@zeta.org.au Subject: Re: ed0 timeouts Message-ID: <199611032210.PAA29444@clem.systemsix.com> In-Reply-To: Your message of "Sun, 03 Nov 1996 14:28:30 MST." <199611032128.OAA03249@phaeton.artisoft.com>
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Hi,
>> Huh? forgive me, not enough sleep... Is this sarcasm or a suggestion that
>> is going over my head?
>
> I think if you don't ack it, it will not allow another one in.
^^^
are you refering to the EOI sequence?
it is complicated by the fact that you mask an INT in the IO APIC, but you send
the EOI only to the local APIC, where the IRR & ISR bits are kept. So
delaying the EOI will prevent it from getting to this CPU, but another CPU
could then grab it, which is what we DON'T want. ( the "focus processor"
feature might be a way around this problem ).
>in the long run. From what David said, it looks like this is a
>generic ISA problem; I'd be surprised if it hasn't bit people without
>APIC's.
the big difference is that the 8259 latches INTs when masked, the APIC ignores
them.
>I think the patch Bruce posted is a move in this direction (or at least
>that's what it looked like to me).
me too, but I need to apply the patch and look at it as a complete work, it
touches on areas that have already changed to accommidate the APIC.
there are also (undefined) macros in there that hide details (Bruce: hint,
hint).
--
Steve Passe | powered by
smp@csn.net | FreeBSD
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