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Date: Wed, 04 Jun 2014 11:39:44 +0200
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Subject: Re: [Qemu-devel] [PATCH v3 0/4] cpus: Add generic NMI support
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To: Peter Maydell <peter.maydell@linaro.org>, Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Stefan Hajnoczi <stefanha@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Alexander Graf <agraf@suse.de>, Luiz Capitulino <lcapitulino@redhat.com>, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>, Alex Bligh <alex@alex.org.uk>, Cornelia Huck <cornelia.huck@de.ibm.com>, =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= <afaerber@suse.de>, Richard Henderson <rth@twiddle.net>

Il 04/06/2014 11:33, Peter Maydell ha scritto:
> On 4 June 2014 10:30, Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>> On 06/04/2014 07:16 PM, Peter Maydell wrote:
>>> On 4 June 2014 09:08, Alexey Kardashevskiy <aik@ozlabs.ru> 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?

It's a kind of "emergency button" on real machines.  On PCs it sends an 
NMI and this results in some kind of crash dump if the OS is configured 
appropriately.  The command may be ill-named for historical reasons, but 
the effect is not x86-specific.

Paolo