linux-kernel - Re: [patch] disable NMI watchdog by default

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Date:	Thu, 08 Mar 2007 21:44:38 +0200
From:	Avi Kivity <avi@...o.co.il>
To:	Bill Davidsen <davidsen@....com>
Cc:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch] disable NMI watchdog by default

Bill Davidsen wrote:
>>
>> there's a new NMI watchdog related problem: KVM crashes on certain 
>> bzImages because ... we enable the NMI watchdog by default (even if 
>> the user does not ask for it) , and no other OS on this planet does 
>> that so KVM doesnt have emulation for that yet. So KVM injects a #GP, 
>> which crashes the Linux guest:
>>
> I'm missing something, what limits this to systems running under kvm?
>

Most likely kvm doesn't implement the msrs which drive the nmi 
watchdog.  That makes it a kvm bug, not a problem with the nmi 
watchdog.  Emulating it correctly is fairly difficult, though, 
especially if we want to migrate virtual machines between different 
processor models, so I hope this goes in.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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