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Date: Wed, 20 Mar 2002 12:24:01 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Cc: Martin Wilck <Martin.Wilck@fujitsu-siemens.com>,
        Ingo Molnar <mingo@elte.hu>,
        Linux Kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Severe IRQ problems on Foster (P4 Xeon) system
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	"Maciej W. Rozycki" <macro@ds2.pg.gda.pl>,
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On Tue, Mar 19, 2002 at 03:32:22PM +0100, Maciej W. Rozycki wrote:
>  The value is correct as after issuing the poll i8259 command the next
> read cycle to the PIC returns an IRQ level (0x07 = no IRQ active; it
> shouldn't happen here -- 0x80 is expected for active IRQ 0). 

On Wed, 13 Mar 2002, Martin Wilck wrote:
>> inb(0x20) call is not captured in our protocol, it must occur long after
>> the error. (We saw normal execution of the above code fragment where
>> there is ~1us between the outb and inb, where it is >120us here).


There is/was at least one simulator that shoots the kernel (and
everything else) dead in response to frobbing the PIC while the local
APIC timer etc. are going, and I wouldn't be surprised if there were
some real hardware that did so as well.

(this is the code under if (timer_ack) in do_timer_interrupt())


Cheers,
Bill
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