From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39377) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bUlu7-0002sU-3X for qemu-devel@nongnu.org; Tue, 02 Aug 2016 22:27:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bUlu5-0004aN-Mh for qemu-devel@nongnu.org; Tue, 02 Aug 2016 22:27:31 -0400 Date: Wed, 3 Aug 2016 12:15:49 +1000 From: David Gibson Message-ID: <20160803021549.GH27583@voom.fritz.box> References: <1470111908-8456-1-git-send-email-david@gibson.dropbear.id.au> <20160802050434.GC16350@in.ibm.com> <20160802062050.GZ2588@voom.fritz.box> <20160802062413.627243kvp6wv7xcf@andariel.pipo.sk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="zhtSGe8h3+lMyY1M" Content-Disposition: inline In-Reply-To: <20160802062413.627243kvp6wv7xcf@andariel.pipo.sk> Subject: Re: [Qemu-devel] [PATCH] spapr: Don't support query-hotpluggable-cpus on earlier pseries machine types List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Krempa Cc: Bharata B Rao , imammedo@redhat.com, qemu-devel@nongnu.org, qemu-ppc@nongnu.org, agraf@suse.de --zhtSGe8h3+lMyY1M Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 02, 2016 at 08:24:13AM +0200, Peter Krempa wrote: > On Tue, Aug 02, 2016 at 16:20:50 +1000, David Gibson wrote: > > On Tue, Aug 02, 2016 at 10:34:34AM +0530, Bharata B Rao wrote: > > > On Tue, Aug 02, 2016 at 02:25:08PM +1000, David Gibson wrote: > > > > On Power, support for vCPU hotplug is new in qemu 2.7. However, we > > > > currently implement the query_hotpluggable_cpus hook the same for a= ll > > > > pseries machine type versions. > > > >=20 > > > > However, the old-style CPU initialization doesn't work with the new= query > > > > code, meaning that attempting to use query-hotpluggable-cpus on a > > > > pseries-2.6 or earlier VM will cause qemu to SEGV. > > > >=20 > > > > This fixes the problem by simply disabling the hook for earlier mac= hine > > > > types. > > >=20 > > > I had sent a patch to fix this and a couple of other related issues > > > some time back and it indeed was accepted into your ppc-for-2.7 branc= h. > > >=20 > > > https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg01539.html > > >=20 > > > Only now I am realizing that somehow that patch didn't make it to mai= nline. > >=20 > > Oh.. good point. Sorry, that one somehow slipped through the cracks. > >=20 > > So, the remaining question is, what's the preferred behaviour for > > older machine types: > >=20 > > 1) should query-hotpluggable-cpus give an error, the same as it does > > on machine types which have never supported it (this is what my > > patch does) > >=20 > > or > >=20 > > 2) Should query-hotpluggable-cpus succeed, but return an empty list? > > (this is what Bharata's patch does) > >=20 > > Igor and / or Peter, do you have an opinion on which behaviour is prefe= rable? >=20 > I don't really care which option you select as long as the > 'hotpluggable-cpus' field which is repored in 'query-machines' is set to > false for machine types which don't support it. Libvirt then won't even > call query-hotpluggable-cpus. Ah.. and looking at it more closely, Bharata's older patch will also get that wrong. However, it does some other checks which might make sense. I'll try to merge his approach and mine. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --zhtSGe8h3+lMyY1M Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJXoVPVAAoJEGw4ysog2bOSxicQAJhKnNlJTuLakJTt4BP5c9Mm przP9Q72o2dwVydXdgS57BKO9mpkj6XjHf8EFsVRKRjzIVdz7f21L7bSB1KFgaY6 aeX9GQs5L+GOL8oLKqg/HxSFKBVxZWVID2IItgFjnm1dJPRcj+a0IS2JVoua7j0j 4H0BkjCY4+f9Ki4OjDr2dwpVj3c1Z0cALFb6O3UYo/PtSvMXWvOjLIVPlaJJ/lHT vMHjmOEum4SsxTe8UYJ6rkAt4wlG61+gDjFz6Wrg25ml9/DONLfH1HADA8SkxW1m nYwmD+Mh92gLSqvbtm6zxg88bTI2Hj8RsYInXAKXwB7AIY9xT4y3Mi64T0vrJZ+i ECkYyM0OnwNRJr725Wn3zzuBwFM+sVmhgsVvPbYyhSXFilhNWt7ldWpNfW/6VOq/ o0Q+2GGUtsUDVYIf0I3sE6ZoPvqgPDUMmFx2gRLl3QMNCfVExYEukF0qvzkWg/xj lD0M4wnh+SWkVfAxKsojg7fmHEr7VrZzsX+vx0wrvxDoAKGN2kqAhur6o5rAicme /EjsXE+V117700NXrgSh2/4F1Y2gOelcAJ1yz7hYDx4ZGi/c1GWvt+ZKF6oLpCaq WGGx6QOeh/xLluFbjF14EttRxEUix/3BsttcICeVRQd6W2CfOnToFOxTjoKWA5Nd 5Tf57OnBjWfihirxwMuL =gyGl -----END PGP SIGNATURE----- --zhtSGe8h3+lMyY1M--