Re: A question of perf NMI handler

Cyrill Gorcunov
2010-08-04T16:10:53Z

On Wed, Aug 04, 2010 at 11:50:02AM -0400, Don Zickus wrote:
...
> >
> > Well, first I guess having Yinghai CC'ed is a bonus ;)
> > The second thing is that I don't get why perf handler can't be _last_
> > call in default_do_nmi, if there were any nmi with reason (serr or parity)
> > I think they should be calling first which of course don't eliminate
> > the former issue but somewhat make it weaken.
>
> Because the reason registers are never set. If they were, then the code
> wouldn't have to walk the notify_chain. :-)
>

maybe we're talking about different things. i meant that if there is nmi
with a reason (from 0x61) the handling of such nmi should be done before
notify_die I think (if only I not miss something behind).

> Unknown nmis are unknown nmis, nobody is claiming them. Even worse, there
> are customers that want to register their nmi handler below the perf
> handler to claim all the unknown nmis, so they can be logged on the system
> before being rebooted.

well, perhaps we might need some kind of perf_chain in notifier code and
call for it after die_nmi chain, so the customers you mention may add own
chain for being called last.

>
> Cheers,
> Don
>
-- Cyrill