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From: Vivek Goyal <vgoyal@in.ibm.com>
To: Neil Horman <nhorman@redhat.com>
Cc: kexec@lists.infradead.org
Subject: Re: Timer interrupt lost on some x86_64 systems
Date: Mon, 12 Nov 2007 10:19:03 +0530	[thread overview]
Message-ID: <20071112044903.GA6433@in.ibm.com> (raw)
In-Reply-To: <20071107140006.GC14371@hmsendeavour.rdu.redhat.com>

On Wed, Nov 07, 2007 at 09:00:06AM -0500, Neil Horman wrote:
> Hey all-
> 	I've been getting reports of some x86_64 systems that, on kdump kernel
> boot get stuck in calibrate_delay(),  in both RHEL kernels and upstream kernels.
> The current thinking is that the lapic timer interrupt is no longer getting
> delivered, likely because we handle a crash condition on a cpu that isn't the
> boot cpu.  One known offender is this motherboard:
> http://www.supermicro.com/Aplus/motherboard/Opteron8000/MCP55/H8QM8-2.cfm
> My current thought is that the TIMER_LVT entry is masked on all but the boot cpu
> on this system (which is strange, as I was under the impression that the timer
> interrupt was supposed to be enabled on all CPU's nominally.

I also thought that LAPIC timer interrupts are enabled on all cpus.

>  At any rate, I was
> going to try to read/write the TIMER_LVT on the crashing processor before we
> jump to purgatory, or in purgatory itself, to see if that fixes the problem, but

I think calibrate_dealy() depends on external timer interrupt coming and
not the local APIC timer interrupt. Generally it is 8254 timer chip. Now a
days motherboards seems to be having HPET and I know somebody has reported
problems with HPET where HPET interrupts are not coming in second kernel and
system hangs in second kernel. I suspect  that same might be the issue here.

Thanks
Vivek

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  reply	other threads:[~2007-11-12  4:49 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-07 14:00 Timer interrupt lost on some x86_64 systems Neil Horman
2007-11-12  4:49 ` Vivek Goyal [this message]
2007-11-12 15:17   ` Neil Horman
2007-11-12 15:41     ` Neil Horman
2007-11-13  7:31       ` Vivek Goyal
2007-11-13 14:33         ` Neil Horman
2007-11-14  6:39           ` Vivek Goyal
2007-11-14 11:51             ` Neil Horman
2007-11-22 20:04               ` Eric W. Biederman
2007-11-13  7:22     ` Vivek Goyal

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