From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56396) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVGUa-0007yE-Ca for qemu-devel@nongnu.org; Mon, 15 Feb 2016 05:34:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aVGUX-0006pz-5n for qemu-devel@nongnu.org; Mon, 15 Feb 2016 05:34:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53969) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVGUX-0006ps-05 for qemu-devel@nongnu.org; Mon, 15 Feb 2016 05:34:53 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id A562471 for ; Mon, 15 Feb 2016 10:34:52 +0000 (UTC) Date: Mon, 15 Feb 2016 18:34:40 +0800 From: Peter Xu Message-ID: <20160215103440.GC7978@pxdev.xzpeter.org> References: <1455428503-2113-1-git-send-email-peterx@redhat.com> <87povy5mim.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87povy5mim.fsf@blackfin.pond.sub.org> Subject: Re: [Qemu-devel] [RFC PATCH 0/2] ARM: add QMP command to query GIC version List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: libvir-list@redhat.com, wei@redhat.com, drjones@redhat.com, qemu-devel@nongnu.org, abologna@redhat.com On Mon, Feb 15, 2016 at 10:52:01AM +0100, Markus Armbruster wrote: > Peter Xu writes: > > > For ARM platform, we still do not have any interface to query > > whether current QEMU/host support specific GIC version. This > > patchset is trying to add one QMP interface for that. By querying > > the GIC capability using the new interface, one should know exactly > > what GIC version(s) the platform will support. The capability bits > > will be decided by both QEMU and host kernel. > > > > The current patchset only provides interface for review. Its handler > > is a fake one which returns empty always. > > > > The command interface I am planning to add is something like this: > > > > -> { "execute": "query-gic-capability" } > > <- { "return": [ "gicv2", "gicv2-kvm", "gicv3-kvm" ] } > > > > Currently, all the possible supported GIC versions are: > > > > - gicv2: GIC version 2 without kernel IRQ chip > > - gicv2-kvm: GIC version 2 with kernel IRQ chip > > - gicv3: GIC version 3 without kernel IRQ chip (not supported) > > - gicv3-kvm: GIC version 3 with kernel IRQ chip > > > > Since "gicv3" is still not supported (to use GICv3, kernel irqchip > > support is required for now, which corresponds to "gicv3-kvm"), > > currently the maximum superset of the result should be: > > > > ["gicv2", "gicv2-kvm", "gicv3-kvm"] > > > > Please help review whether the interface suits our need, also please > > point out any error I have made. > > Adding ad hoc queries as we go won't scale. Is there really no generic > way to get this information, e.g. with qom-get? Haven't used "qom-get" before, but it seems to fetch one property for a specific object. If so, will it be strange to hide some capability bits into every GIC objects (though there is possibly one object)? I agree that we should keep the interface as simple as possible. I see that there are already commands that works just like this one, which is to query some capabilities from QEMU, like: - query-dump-guest-memory-capability - query-migrate-capabilities So... besides the original proposal, what about adding a generic QMP command to query all kinds of capabilities (and let GIC be the first item)? Or any other way to avoid adding a new command? Thanks. Peter > > > One question: how should I make this command "ARM only"? I see that > > in qmp-commands.hx, I can use something like "#if defined > > TARGET_ARM" to block out ARM specified commands, however how should > > I do the similiar thing in qapi-schema.json? > > Have a look at the #if in qmp-commands.hx.