Re: [Qemu-devel] [PATCH v5 1/5] arm: qmp: add GICCapability struct

From: Peter Xu <peterx@redhat.com>
To: Markus Armbruster <armbru@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
Subject: Re: [Qemu-devel] [PATCH v5 1/5] arm: qmp: add GICCapability struct
Date: Thu, 24 Mar 2016 10:27:05 +0800	[thread overview]
Message-ID: <20160324022705.GZ28183@pxdev.xzpeter.org> (raw)
In-Reply-To: <87r3f12ph6.fsf@blackfin.pond.sub.org>

On Wed, Mar 23, 2016 at 04:17:25PM +0100, Markus Armbruster wrote:
> 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.

Thanks, will include this in v7.

-- peterx