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SubjectRe: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking
On 09/07/2011 04:44 PM, Don Zickus wrote:
> >
> > Is there a way to tell whether an NMI was internally or externally
> > generated?
> >
> > I don't think so, especially as two or more NMIs can be coalesced.
> > So any NMI received on this first cpu has to check the NMI reason
> > port?
>
> Well we cheat and execute all the nmi handlers first. If they come back
> as handled, we skip the check for the external NMI.

And hope that no other NMI was generated while we're handling this one.
It's a little... fragile?

> But you are right, other than checking the reason port, there isn't a way
> to determine if an NMI is internally or externally generated.

Ouch.

>
> >
> > >>
> > >> But on the other hand, I don't really care if you can say that this path
> > >> will never be called in a virtual machine.
> > >
> > >Does virtual machines support hot remove of cpus? Probably not
> > >considering bare-metal barely supports it.
> > >
> >
> > They do.
>
> But vcpus probably don't have the notion of a bsp cpu, so perhaps virtual
> machines can get away with it easier? (I don't know enough about the hot
> cpu remove code to really explain it, just enough to know it can cause
> problems and people are trying to address it).
>

The concept of a bsp exists in exactly the same way as on real hardware.

--
error compiling committee.c: too many arguments to function



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