linux-kernel - Re: 2.6.27-rc3: 'APIC error on CPU1: 00(40)', but only on resume!

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Message-ID: <19f34abd0808210520q60357776xbfcf288018e04161@mail.gmail.com>
Date:	Thu, 21 Aug 2008 14:20:26 +0200
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, "Frans Pop" <elendil@...net.nl>,
	linux-kernel@...r.kernel.org, "Andi Kleen" <andi@...stfloor.org>,
	"Ingo Molnar" <mingo@...e.hu>
Subject: Re: 2.6.27-rc3: 'APIC error on CPU1: 00(40)', but only on resume!

On Thu, Aug 21, 2008 at 1:51 PM, Maciej W. Rozycki <macro@...ux-mips.org> wrote:
>  Otherwise there is no correlation between the sequence of APIC writes and
> an error triggering -- a bad vector in a LVT or interrupt redirection
> entry will be reported whenever its associated interrupt line gets active
> even though the entry might have been initialised long ago.  Depending on
> the device signalling hardware interrupts may quite often be ignored for a
> long time without affecting the stability of the rest of the system.

Ah, right. Here is a dump of the LVT registers:

[00000320] = 000100ef
[00000330] = 00000200
[00000340] = 00010000
[00000350] = 00010700
[00000360] = 00000400
[00000370] = 000000fe

Maybe I've misunderstood something (again), but should those vectors
really be 0 for 330-360? (At least 330 + 360, which are not masked.)

Intel manual says: "Receive Illegal Vector : Set when the local APIC
detects an illegal vector in the message it received, including an
illegal vector code in the local vector table interrupts or in a
self-interrupt."

And 0 is clearly an illegal value for the vector code: "When an
interrupt vector in the range 0 to 15 is sent or received through the
local APIC, the APIC indicates an illegal vector in its Error Status
Register [...]".

But I still find the whole thing slightly confusing. Will play a bit
with the LVT, maybe I can learn something more :-) Thanks for the
help!


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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