From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42725) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bX98d-0006P1-N9 for qemu-devel@nongnu.org; Tue, 09 Aug 2016 11:40:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bX98a-0007at-JN for qemu-devel@nongnu.org; Tue, 09 Aug 2016 11:40:19 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42372 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bX98a-0007aT-Ef for qemu-devel@nongnu.org; Tue, 09 Aug 2016 11:40:16 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u79FdjUB064340 for ; Tue, 9 Aug 2016 11:40:15 -0400 Received: from e28smtp06.in.ibm.com (e28smtp06.in.ibm.com [125.16.236.6]) by mx0b-001b2d01.pphosted.com with ESMTP id 24na1y09aw-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 09 Aug 2016 11:40:14 -0400 Received: from localhost by e28smtp06.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 9 Aug 2016 21:10:11 +0530 Date: Tue, 9 Aug 2016 21:09:53 +0530 From: Bharata B Rao Reply-To: bharata@linux.vnet.ibm.com References: <1470734229-10832-1-git-send-email-thuth@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1470734229-10832-1-git-send-email-thuth@redhat.com> Message-Id: <20160809153953.GC3027@in.ibm.com> Subject: Re: [Qemu-devel] [PATCH for-2.7 0/5] spapr: Fix regression in CPU alias handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: David Gibson , qemu-ppc@nongnu.org, Alexander Graf , qemu-devel@nongnu.org, abologna@redhat.com On Tue, Aug 09, 2016 at 11:17:04AM +0200, Thomas Huth wrote: > There is a regression with the "-cpu" parameter which has been > introduced by the spapr CPU hotplug code: We used to allow to specify > a "CPU family" name with the "-cpu" parameter when running on KVM so > that the user does not need to know the gory details of the exact > CPU version of the host CPU. For example, it was possible to > use "-cpu POWER8" on a POWER8E host CPU. This behavior does not > work anymore with the new hot-pluggable spapr-cpu-core types. > Since libvirt already heavily depends on the old behavior, this > is quite a severe regression in the QEMU parameter interface, thus > I think these patches should still go into 2.7 if possible, to avoid > that we break the "upper layers" with the final 2.7 release. I believed that "-cpu POWER8" on POWER8E host was broken in a way as the guest CPUs were getting reported as POWER8E instead of POWER8 (/proc/cpuinfo of guest) cpu : POWER8E (raw), altivec supported I thought, the correct configuration should have been cpu : POWER8 (architected), altivec supported which is what you get when you use POWER8 in compat mode on POWER8E host like below: -cpu host -global driver=host-powerpc64-cpu,property=compat,value=power8 However as you note libvirt is dependent on supporting POWER8 and there have been discussions and conclusions on this earlier, I guess it is better now to have your patchset to restore the expectations of libvirt. Regards, Bharata.