From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53713) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tiqxq-0001Ll-9I for qemu-devel@nongnu.org; Wed, 12 Dec 2012 13:23:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tiqxl-0005WK-SW for qemu-devel@nongnu.org; Wed, 12 Dec 2012 13:23:26 -0500 Received: from cantor2.suse.de ([195.135.220.15]:50603 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tiqxl-0005W8-JD for qemu-devel@nongnu.org; Wed, 12 Dec 2012 13:23:21 -0500 Message-ID: <50C8CB95.4020709@suse.de> Date: Wed, 12 Dec 2012 19:23:17 +0100 From: Alexander Graf MIME-Version: 1.0 References: <1355317734-55761-1-git-send-email-jfrei@linux.vnet.ibm.com> <1355317734-55761-4-git-send-email-jfrei@linux.vnet.ibm.com> <50C88BED.6000000@suse.de> <50C89D30.4020508@linux.vnet.ibm.com> <50C8B0AC.7010500@suse.de> In-Reply-To: <50C8B0AC.7010500@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 3/3] S390: Enable -cpu help and QMP query-cpu-definitions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?ISO-8859-1?Q?Andreas_F=E4rber?= Cc: Heinz Graalfs , qemu-devel , Viktor Mihajlovski , Christian Borntraeger , Jens Freimann , Cornelia Huck , Einar Lueck , Richard Henderson On 12/12/2012 05:28 PM, Andreas F=E4rber wrote: > Am 12.12.2012 16:05, schrieb Viktor Mihajlovski: >> On 12/12/2012 02:51 PM, Andreas F=E4rber wrote: >>>> + (*cpu_fprintf)(f, "s390 %16s\n", "[host]"); >>> Note that the square-bracket notation was specific to x86 when it >>> distinguished between built-in and config-based models. >>> >> OK, since libvirt capable of dealing with s390 cpu models will >> never see this, we can change it any way that is wanted. >> So, host without brackets? > Yes, but see below... Yes, and with #ifdef CONFIG_KVM :). That way the TCG behavior stays=20 untouched. > >>> "host" only makes sense for KVM, not for TCG. So we would need one ot= her >>> placeholder model for libvirt. >> see my reply to Alex' comment: the placeholder name must be chosen >> carefully, i.e. future-proof > On further thoughts, didn't we discuss that the issue libvirt wants to > address is that migration from z10 to z9 must fail? That's not solved > with -cpu host, we would need two other models then. IMO ideally -cpu > host should have the same semantics as on x86, that is passing the host > features through mostly 1:1. IIUC there is currently no way to not do s= o? That is another problem that we need to solve, but one thing at a time. > What about future-wise having -cpu host not be a subclass and instead > behaving like Alex' -cpu best, given the above semantics? What I am jus= t > worried about with this patch is cementing the use of -cpu host into > libvirt when that is not a mid-term solution. I think on s390 we can get away with the same method as ppc for -cpu=20 host, which basically is -cpu best without fuzziness. Alex