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Date: Wed, 08 Aug 2007 20:15:32 +0200
From: Martin Wilck <martin.wilck@...itsu-siemens.com>
To: "vgoyal@...ibm.com" <vgoyal@...ibm.com>
Cc: Chip Coldwell <coldwell@...hat.com>,
Haren Myneni <hbabu@...ibm.com>,
"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: PATCH/RFC: [kdump] fix APIC shutdown sequence
Vivek Goyal wrote:
> But the issue here seems to be that LAPIC state got clear but IRR bit
> at IOAPIC bit is not cleared because IOAPIC vector information was deleted
> in first kernel and now upon receiving EOI, it does not know this EOI belongs
> to which vector.
I am making another experiment right now. I check the LAPIC ISR flags in
machine_crash_shutdown() before disabling the LAPIC, trying to send EOI if
I find one ISR bit set. So far, I haven't seen a single case where an ISR bit
was set, but several (9) where the IO-APIC IRR bit was set. OTOH, I know that if
I'd re-enable IRQs, IRQ 225 would be raised. The whole thing is done before
disable_IO_APIC().
Don't ask me for an explanation why I don't see the ISR bits.
The arch/x86_64/kernel/crash.c portion of the patch I am using is attached for
your reference. The rest is the same as for the original patch.
Martin
--
Martin Wilck
PRIMERGY System Software Engineer
FSC IP ESP DE6
Fujitsu Siemens Computers GmbH
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Email: mailto:martin.wilck@...itsu-siemens.com
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View attachment "kdump_23.diff" of type "text/x-patch" (3926 bytes)
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