From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43128) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKhgO-0008Oy-7j for qemu-devel@nongnu.org; Tue, 13 Jun 2017 05:00:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dKhgG-0003kk-Ms for qemu-devel@nongnu.org; Tue, 13 Jun 2017 05:00:16 -0400 Date: Tue, 13 Jun 2017 10:00:03 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170613090002.GA2096@work-vm> References: <149685579678.12025.9278446121024037161.stgit@bahia.lan> <149685584629.12025.14875914798241845062.stgit@bahia.lan> <20170608040857.GV13397@umbus.fritz.box> <20170608115410.2e7a2511@bahia.ttt.fr.ibm.com> <20170612142456.GJ18542@umbus> <20170613093359.4567ba94@bahia.ttt.fr.ibm.com> <20170613080631.GB30171@umbus> <20170613104003.233e21d5@bahia.ttt.fr.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20170613104003.233e21d5@bahia.ttt.fr.ibm.com> Subject: Re: [Qemu-devel] [PATCH v3 5/5] spapr: fix migration of ICPState objects from/to older QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: David Gibson , qemu-devel@nongnu.org, qemu-ppc@nongnu.org, Cedric Le Goater , Juan Quintela * Greg Kurz (groug@kaod.org) wrote: > On Tue, 13 Jun 2017 16:06:31 +0800 > David Gibson wrote: >=20 > > On Tue, Jun 13, 2017 at 09:33:59AM +0200, Greg Kurz wrote: > [...] > > > > > > > +static void pre_2_10_vmstate_register_dummy_icp(sPAPRMachine= State *spapr, int i) > > > > > > > +{ > > > > > > > + bool *flag =3D &spapr->pre_2_10_ignore_icp[i]; > > > > > > > + > > > > > > > + g_assert(!*flag); =20 > > > > > >=20 > > > > > > Apart from this assert(), you never seem to test the values in = the > > > > > > pre_2_10_ignore_icp() array, so it seems a bit pointless. > > > > > > =20 > > > > >=20 > > > > > There's the opposite check in pre_2_10_vmstate_unregister_dummy_i= cp(). > > > > > But I agree it isn't really useful... but more because of paranoi= a :) =20 > > > >=20 > > > > I'm all for paranoid assert()s if they can be made using data readi= ly > > > > to hand. Adding a data structure just for the purpose of making an > > > > assert() later, not so much. > > > > =20 > > >=20 > > > It is also passed as opaque argument to vmstate_register(), where it = is > > > used as a key when calling vmstate_unregister(). I could possibly pass > > > (void *) i instead, but I'm not a big fan of hijacking pointer argume= nts > > > to pass numbers. =20 > >=20 > > Ah, I see your point. Creating an array, purely to generate arbitrary > > pointers is also kind of ugly, though. Really the cpu_index / XICS > > server number makes sense to identify the vmstate, but it looks like > > vmstate_unregister() doesn't take that. > >=20 >=20 > Indeed... what about adding a vmstate_unregister_by_instance_id() then ? >=20 > Cc'ing Juan and David. So what's the problem with a (void *)i ? It's simple, as long as you're not actually using the opaque anywhere it's easy. Note from a quick glance at your patch; will this work migrating =66rom this 2.10 -> 2.9 ? Are your dummy vmstate's really good enough for the 2.9 ? Dave > -- > Greg -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK