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    SubjectRe: [RFC] x86, NMI, Treat unknown NMI as hardware error
    On 05/15/2011 02:34 PM, Cyrill Gorcunov wrote:
    > 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.

    The white list mechanism is not sufficient? Spurious unknown NMI can
    occur on white list machines? People don't want to protect their data?

    >> 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 ;)

    As for go notifiers or not. IMHO, a rule can be:

    - If it is something like a driver, than it should go notifier
    - If it is architectural/PC defacto standard, it can sit outside of
    notifier.

    I think that seeing unknown NMI as hardware error should be part of PC
    defacto standard. Do you think so?

    Best Regards,
    Huang Ying


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