Re: [PATCH] NMI watchdog config option (was: Re: [PATCH] NMI lockup and AltSysRq-P dumping calltraces on _all_ cpus via NMI IPI)

["Martin J. Bligh" <mbligh@mbligh.org>]

>> > So much has changed in there that we might have fixed it by accident, and I
>> > do recall a couple of fundamental and subtle NMI bugs being fixed.  So
>> > yeah, it might be worth enabling it by default again.  Care to send a patch
>> > which does that?
>> 
>> There are some unfixable machine issues - for instance, the IBM
>> Netfinity 8500R corrupts one of the registers (ebx?) every time we get
>> an NMI for us, and panics. Probably other boxes you mention above have
>> similar issues? But it's not our code that's at fault ...
> 
> That sounds like an instant crash.  The problems which were reported a few
> years back were different - mysterious lockups after hours or days of
> operation.

Dunno, might have been a race, or only happened if the wind was blowing
North at the time. More likely different machines had different forms of
failures caused by various obscure bugs ;-) If you're really curious, I 
could go test it I spose.
 
>> In light of this, I don't think it's a good idea to enable NMI by default,
>> at least not without a blacklist function of some sort?
> 
> OK, thanks - I'll leave things as they stand.

Thanks. I think it's safer that way ...

M.