linux-kernel - Re: v2.6.27-rc7: x86: #GP on panic?

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Date:	Sat, 27 Sep 2008 20:43:44 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Vegard Nossum <vegard.nossum@...il.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: v2.6.27-rc7: x86: #GP on panic?


* H. Peter Anvin <hpa@...or.com> wrote:

> Vegard Nossum wrote:
>> On Thu, Sep 25, 2008 at 10:49 PM, H. Peter Anvin <hpa@...or.com> wrote:
>>>> Seems like an external interrupt happened and was delivered after the sti?
>>>>
>>>> Hm. I guess it smells like a qemu bug since it's rather easily
>>>> reproducible here and sounds strange that nobody else saw it. Is qemu
>>>> 0.9.1.
>>>>
>>> Yes, but there shouldn't be any external interrupts that could turn into  a
>>> divide error.  It really smells like a Qemu problem -- possibly even a Qemu
>>> miscompile -- to me.
>>>
>>> Does it reproduce in KVM?
>>
>> I have no computer that can do KVM, sorry :-(
>>
>> Stack trace contains IO_APIC functions, so it seems that maybe the
>> emulated IOAPIC is trying to (erroneously) deliver an int 0 (for some
>> reason)? But I don't know, that's just speculation which can be done
>> better by others, so I will stop now :-)
>>
>
> I suspect it's a problem in Qemu's IOAPIC model, but it's hard to know  
> for sure.

yes - it smells like it tries to deliver vector 0, after the panic code 
has deinitialized the lapic / ioapic.

	Ingo
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