Re: [RFC] x86, NMI, Treat unknown NMI as hardware error

From: Cyrill Gorcunov <gorcunov@gmail.com>
To: huang ying <huang.ying.caritas@gmail.com>
Cc: Huang Ying <ying.huang@intel.com>, Ingo Molnar <mingo@elte.hu>,
	Don Zickus <dzickus@redhat.com>,
	linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
	Robert Richter <robert.richter@amd.com>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: [RFC] x86, NMI, Treat unknown NMI as hardware error
Date: Sun, 15 May 2011 10:34:59 +0400	[thread overview]
Message-ID: <4DCF7413.4070704@gmail.com> (raw)
In-Reply-To: <BANLkTin1pvdnXtw53MhwfCsEQpsu0TUUmg@mail.gmail.com>

On 05/15/2011 04:06 AM, huang ying wrote:
...
>>
>> yes, is not good. But at least we *must* provide a way to turn this new feature off
>> via command line I think. One of a reason for me is perf unknown nmis (at moment we seems
>> to have captured and cured all parasite NMIs sources but there is no guarantee we wont
>> meet them in future due to some code change or whatever). And bloating trap.c with
>> new if()'s is not that good I guess, that is why I asked if there a way to do all the
>> work via notifiers ;)
> 
> Yes.  We should consider about perf unknown NMI issues.  But compared
> with pushing all magic to user, I think the better way is to have a
> better default behavior in kernel.  For example, we can turn off
> unknown NMI as hwerr logic temporarily if there are more than 1 perf
> NMI events in action.  Is that reasonable?

  I'm personally fine even if it's enabled by default, only worried to have
an option to disable hwerr from boot line.

> 
> And, I am not a big fan of notifiers, that makes code hard to be
> understood.  If you have concerns about the size of traps.c, we can
> move all NMI logic to a new file.

  Ying, the concern is rather related to the code scheme in general. Since
we have notifiers I think the better way to be consistent here and use
hwerr notifier too. But it's IMHO ;)

> 
> Best Regards,
> Huang Ying

-- 
            Cyrill