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From: Markus Armbruster <armbru@redhat.com>
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Date: Wed, 23 Mar 2016 16:17:25 +0100
In-Reply-To: <20160323142500.GU28183@pxdev.xzpeter.org> (Peter Xu's message of
	"Wed, 23 Mar 2016 22:25:00 +0800")
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Subject: Re: [Qemu-devel] [PATCH v5 1/5] arm: qmp: add GICCapability struct
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To: Peter Xu <peterx@redhat.com>
Cc: wei@redhat.com, peter.maydell@linaro.org, drjones@redhat.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, abologna@redhat.com, qemu-arm@nongnu.org

Peter Xu <peterx@redhat.com> writes:

> On Wed, Mar 23, 2016 at 01:21:52PM +0100, Markus Armbruster wrote:
>> Can you tell me what a management application is supposed to do with the
>> information returned by query-gic-capabilities?  Not just in general
>> terms, like "using this information, libvirt can warn the user during
>> configuration of guests when specified GIC device type is not supported,
>> but specifics.  Something like "-frobnicate mutter=mumble won't work
>> unless query-gic-capabilities reports emulated version 2 is supported"
>> for every piece of configuration that should be vetted against
>> query-gic-capabilities.
>
> I suppose that won't be a very big problem since possibly only
> libvirt will use it... I agree that it's better to explain it more
> clearly though. How about adding these lines into patch 1 commit
> message:
>
> """
> For example, if we got the query result:
>
> {"return": {"capabilities":
>   [ {"emulated": false, "version": 3, "kernel": true},
>     {"emulated": true, "version": 2, "kernel": false} ] } }
>
> Then it means that we support emulated GIC version 2 using:
>
>   qemu-system-aarch64 -M virt,gic-version=2 ...
>
> or kvm-accelerated GIC version 3 using:
>
>   qemu-system-aarch64 -enable-kvm -M virt,gic-version=3 ...

I'd say "qemu-system-aarch64 -M virt,accel=kvm,gic=version=3"

> If we specify other explicit GIC version rather than the above, QEMU
> will not be able to boot.
> """

Works for me.