[Xen-devel] Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking

[Avi Kivity <avi@xxxxxxxxxx>]

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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