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[Xen-devel] Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking
- To: Don Zickus <dzickus@xxxxxxxxxx>
- From: Avi Kivity <avi@xxxxxxxxxx>
- Date: Wed, 07 Sep 2011 18:11:14 +0300
- Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Marcelo Tosatti <mtosatti@xxxxxxxxxx>, Nick Piggin <npiggin@xxxxxxxxx>, KVM <kvm@xxxxxxxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 07 Sep 2011 09:10:01 -0700
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
On 09/07/2011 04:44 PM, Don Zickus wrote:
> Is there a way to tell whether an NMI was internally or externally
> 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
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.
> >> 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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