Messages in this thread | | | Date | Thu, 4 Sep 2008 17:22:45 -0400 | From | Don Zickus <> | Subject | Re: [PATCH RFC] NMI Re-introduce un[set]_nmi_callback |
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On Thu, Sep 04, 2008 at 10:53:45PM +0200, Andi Kleen wrote: > So if your handler can decide "This is an NMI that came from > a source i know about" it can be a proper[1] NMI cititzen.
The way it was explained to me months ago, is that it can't. Currently it works by making sure the nmi watchdog is disabled on the box (either compiled off, or nmi_watchdog=0). Then it registers itself on the DIE chain. Because it is on the top of the chain, it just so happens to be the first handler to process the NMIs, so HP is happy. Kdump works because it registers later on top of the HP handler thus it is called before HP can panic the box. However, I suspect if one were to run oprofile in nmi mode, HP would panic the box on the first profile point.
> > Otherwise it will be hard to make it coexist nicely.
Hence our attempt at a solution by creating a registration for a new nmi_handler, which in hindsight seemed to miss a couple of cases.
Cheers, Don
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