From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44346) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKnxQ-0003iD-64 for qemu-devel@nongnu.org; Wed, 06 Jul 2016 10:37:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKnxK-00066M-3P for qemu-devel@nongnu.org; Wed, 06 Jul 2016 10:37:43 -0400 Received: from 15.mo7.mail-out.ovh.net ([87.98.180.21]:42923) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKnxJ-000669-TA for qemu-devel@nongnu.org; Wed, 06 Jul 2016 10:37:38 -0400 Received: from player739.ha.ovh.net (b9.ovh.net [213.186.33.59]) by mo7.mail-out.ovh.net (Postfix) with ESMTP id E2C0EFFCFD9 for ; Wed, 6 Jul 2016 16:37:36 +0200 (CEST) Date: Wed, 6 Jul 2016 16:37:26 +0200 From: Greg Kurz Message-ID: <20160706163726.1a955123@bahia.lan> In-Reply-To: <20160706142101.GG25522@in.ibm.com> References: <1467795561-1007-1-git-send-email-bharata@linux.vnet.ibm.com> <1467795561-1007-4-git-send-email-bharata@linux.vnet.ibm.com> <20160706140114.2ff04caf@172-15-179-184.lightspeed.austtx.sbcglobal.net> <20160706142101.GG25522@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH v1 3/5] spapr: Implement CPUClass::get_migration_id() for PowerPC CPUs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bharata B Rao Cc: Igor Mammedov , qemu-devel@nongnu.org, qemu-ppc@nongnu.org, david@gibson.dropbear.id.au, nikunj@linux.vnet.ibm.com, pbonzini@redhat.com On Wed, 6 Jul 2016 19:51:01 +0530 Bharata B Rao wrote: > On Wed, Jul 06, 2016 at 02:01:14PM +0200, Igor Mammedov wrote: > > On Wed, 6 Jul 2016 14:29:19 +0530 > > Bharata B Rao wrote: > > > > > cpu_index is used as migration_id by default. For machine type > > > versions that set use-migration-id property, cpu_dt_it is returned. > > > > > > Signed-off-by: Bharata B Rao > > > --- > > > target-ppc/translate_init.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c > > > index efd6b88..9ca2f5e 100644 > > > --- a/target-ppc/translate_init.c > > > +++ b/target-ppc/translate_init.c > > > @@ -10359,6 +10359,17 @@ static gchar *ppc_gdb_arch_name(CPUState *cs) > > > #endif > > > } > > > > > > +static int ppc_cpu_get_migration_id(CPUState *cs) > > > +{ > > > + PowerPCCPU *cpu = POWERPC_CPU(cs); > > > + > > > + if (cs->use_migration_id) { > > > + return (int) cpu->cpu_dt_id; > > Could cpu_dt_id have value bigger than 32bit int? If yes, it's not safe > > to do so, that's the reason why I'm going to use index in possible_cpus > > on ARM and for the sake of uniformity do the same for x86 (even though > > it's possible to use 32bit APIC ID). > > For the existing max_cpus limit, 32 bit should be fine, but obviously > that is not good and future safe. > And BTW, cpu_dt_id is actually an int > I had a brief look at the implementation around possible_cpus in > x86, let me see if I can do something similar for generating stable > ids for PowerPC. I thought device tree ID would be our stable id, but > that being 64 bit and migration code requiring 32 bit value isn't > helping :( > Yes you have stable ids, look at my other answer to this patch. > Regards, > Bharata. >