From mboxrd@z Thu Jan  1 00:00:00 1970
From: Markus Armbruster <armbru@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2] event: Add source information to SHUTDOWN
Date: Thu, 20 Apr 2017 18:12:42 +0200
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Cc: "Daniel P. Berrange" <berrange@redhat.com>,
        Peter Maydell <peter.maydell@linaro.org>,
        "open list\:Overall" <kvm@vger.kernel.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
        qemu-devel@nongnu.org, Scott Wood <scottwood@freescale.com>,
        Gerd Hoffmann <kraxel@redhat.com>,
        "Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
        Rob Herring <robh@kernel.org>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Magnus Damm <magnus.damm@gmail.com>,
        Alexander Graf <agraf@suse.de>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Anthony Perard <anthony.perard@citrix.com>,
        "open list\:X86" <xen-devel@lists.xenproject.org>,
        Richard Henderson <rth@twiddle.net>,
        Artyom Tarasenko <atar4qemu@gmail.com>,
        Eduardo Habkost <ehabkost@redhat
To: Eric Blake <eblake@redhat.com>
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In-Reply-To: <1f4e72ed-fab1-7099-768e-2a111df3a633@redhat.com> (Eric Blake's
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Eric Blake <eblake@redhat.com> writes:

> On 04/20/2017 07:09 AM, Daniel P. Berrange wrote:
>
>>>> +++ b/qapi/event.json
>>>> @@ -10,6 +10,10 @@
>>>>  # Emitted when the virtual machine has shut down, indicating that qemu is
>>>>  # about to exit.
>>>>  #
>>>> +# @guest: If true, the shutdown was triggered by a guest request (such as
>>>> +# executing a halt instruction) rather than a host request (such as sending
>>>> +# qemu a SIGINT). (since 2.10)
>>>> +#
>>>
>>> "executing a halt instruction" suggests "halt" is a machine instruction.
>
> Which is indeed what most of the places I patched to pass 'true' are
> emulating - the machine halt instruction.
>
>>> I think you mean /usr/sbin/halt.  Suggest something like "executing a
>>> halt command".
>> 
>> Well technically /usr/sbin/halt just terminates all processes / kernel and
>> halts CPUs, but the virtual machine is still active (and a 'reset' in the
>> monitor can start it again. /usr/sbin/poweroff is what actually does the
>> ACPI poweroff to trigger QEMU to exit[1]
>
> I'm thinking of this wording:
>
> triggered by a guest request (such as the guest running
> /usr/sbin/poweroff to trigger an ACPI shutdown or machine halt instruction)

A quick glance at the patch suggests the instructions in question are
typically writes to some device register.  I wouldn't call them "halt
instructions", in particular since there's the x86 "hlt" instruction
that does something else.