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Date: Wed, 11 Jun 2014 20:59:55 +1000
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Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v3 1/4] cpus: Define NMI callback
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Stefan Hajnoczi <stefanha@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Alexander Graf <agraf@suse.de>, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>, Alex Bligh <alex@alex.org.uk>, Cornelia Huck <cornelia.huck@de.ibm.com>, Luiz Capitulino <lcapitulino@redhat.com>, Andreas =?ISO-8859-1?Q?F=E4rber?= <afaerber@suse.de>, Richard Henderson <rth@twiddle.net>

On Wed, 2014-06-11 at 12:47 +0200, Paolo Bonzini wrote:
> Ok, I can buy removing the support for CPU != 0.  But still, the 
> overengineering remains.
> 
> If Alexey needs to trigger the NMI on all CPUs, simply moving the new 
> method from CPU to Machine, and blindly using first_cpu in s390 and x86 
> makes the most sense.

I can imagine a future where we would want to programatically trigger the
sreset (the NMI is basically a soft reset for us) on a specific target CPU
so it does make some sense to have a per CPU method and have the monitor
"nmi" command call it on all of them. But it's not a huge deal if you decide
to just make it as machine for now.

This is more than just a "debug" feature however, it is generally used to
trigger kdump on crashed partitions (this feature is called "dump" in pHyp).

Cheers,
Ben.