Re: [patch] disable NMI watchdog by default

Bill Davidsen
2007-03-05T16:01:05Z

Ingo Molnar wrote:
> From: Ingo Molnar <mingo@elte.hu>
> Subject: [patch] disable NMI watchdog by default
>
> 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:
>
> general protection fault: 0000 [#1]
> PREEMPT SMP
> Modules linked in:
> CPU: 0
> EIP: 0060:[<c011a8ae>] Not tainted VLI
> EFLAGS: 00000246 (2.6.20-rc5-rt0 #3)
> EIP is at setup_apic_nmi_watchdog+0x26d/0x3d3
>
> and no, i did /not/ request an nmi_watchdog on the boot command line!
>
> Solution: turn off that darn thing! It's a debug tool, not a 'make life
> harder' tool!!
>
> with this patch the KVM guest boots up just fine.
>
> And with this my laptop (Lenovo T60) also stops its sporadic hard
> hanging (sometimes in acpi_init(), sometimes later during bootup,
> sometimes much later during actual use) as well. It hung with both
> nmi_watchdog=1 and nmi_watchdog=2, so it's generally the fact of NMI
> injection that is causing problems, not the NMI watchdog variant, nor
> any particular bootup code.
>
> The patch is unintrusive.

I'm missing something, what limits this to systems running under kvm?

--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot