From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44081) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5dxk-00020K-QK for qemu-devel@nongnu.org; Tue, 21 Jan 2014 11:14:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W5dxe-0003jk-Fr for qemu-devel@nongnu.org; Tue, 21 Jan 2014 11:14:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:17051) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5dxe-0003jX-86 for qemu-devel@nongnu.org; Tue, 21 Jan 2014 11:13:58 -0500 Message-ID: <52DE9CBE.7080009@redhat.com> Date: Tue, 21 Jan 2014 17:13:50 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1390228618-21663-1-git-send-email-ehabkost@redhat.com> <52DD9F77.4040904@suse.de> <52DE45E3.5010208@redhat.com> <52DE978E.3020309@suse.de> In-Reply-To: <52DE978E.3020309@suse.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] target-i386: enable x2apic by default on more recent CPU models List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?ISO-8859-15?Q?Andreas_F=E4rber?= Cc: Eduardo Habkost , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Bandan Das , Anthony Liguori , Igor Mammedov Il 21/01/2014 16:51, Andreas F=E4rber ha scritto: >> > We already do that for other bits (e.g. XSAVE/OSXSAVE), > Please point me to the commit, a search for xsave did not come up with = a > commit changing such a thing - either it did not go through my queue or > it slipped me through: Bugs are no excuse to produce more bugs. I meant that "-cpu SandyBridge" with TCG produces a CPU that doesn't=20 have XSAVE. >> > and in fact it >> > is the same that we do for KVM: the KVM_GET_SUPPORTED_CPUID result i= s >> > used to trim the generic feature bits. > Our model definitions are the place to put stuff that real CPUs have. > Either the CPU has it or it doesn't. If it does, then this patch is > fully correct and it's TCG's job to mask things out. If we're adding > artificial flags to the generic model definitions just to make KVM > faster, then it is wrong - we have a choice of post_initialize and > realize hooks for that. It would make TCG faster as well, and there would be no reason really to=20 avoid the "artificial" x2apic on TCG, if TCG implemented x2apic at all. Paolo