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Re: [Qemu-ppc] [Qemu-devel] [PATCH v3 0/4] cpus: Add generic NMI support

From: Alexander Graf
Subject: Re: [Qemu-ppc] [Qemu-devel] [PATCH v3 0/4] cpus: Add generic NMI support
Date: Wed, 04 Jun 2014 11:38:27 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.5.0

On 04.06.14 11:33, Peter Maydell wrote:
On 4 June 2014 10:30, Alexey Kardashevskiy <address@hidden> wrote:
On 06/04/2014 07:16 PM, Peter Maydell wrote:
On 4 June 2014 09:08, Alexey Kardashevskiy <address@hidden> wrote:
This adds an NMI handler per CPUs. x86, s390 and ppc CPUS are supported.

The change to existing behaviour is that x86 only delivers NMI to
the current monitored CPU now, not to every CPU.
So this series means that the "nmi" command and handler does
  * NMI on x86
  * reset on PPC
The vector is called "reset" but it is an interrupt, and I do not see any
way to mask it.

  * restart on S390
The vector is called "restart" but it is still an interrupt.
So? ARM has an interrupt called "NMI" but there's zero reason
you'd want to poke it from the monitor, any more than you'd
want to try to hand-send any other kind of interrupt.

That doesn't seem generic at all, and suggests this should
not be a common CPU method/callback.
Oh. Ok. Suggestions?
I dunno. What are you actually trying to achieve?

Linux configures certain interrupts to trigger an emergency situation - usually to get you into a debugger or to start a crash kexec kernel.

The command is called "nmi" because it originally was used on x86 to do this and there the NMI interrupt is the one Linux uses for that purpose. In fact, on x86 bringup systems you often have an "NMI" button next to the "reset" and "power on" buttons.


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