From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40523) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zti6J-0000id-T0 for qemu-devel@nongnu.org; Tue, 03 Nov 2015 15:22:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zti6G-0007TE-Pa for qemu-devel@nongnu.org; Tue, 03 Nov 2015 15:22:39 -0500 Received: from mail-wm0-x234.google.com ([2a00:1450:400c:c09::234]:37820) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zti6G-0007Ss-Iw for qemu-devel@nongnu.org; Tue, 03 Nov 2015 15:22:36 -0500 Received: by wmff134 with SMTP id f134so24834776wmf.0 for ; Tue, 03 Nov 2015 12:22:35 -0800 (PST) Sender: Paolo Bonzini References: <1446580695-28525-1-git-send-email-ehabkost@redhat.com> From: Paolo Bonzini Message-ID: <56391786.5000808@redhat.com> Date: Tue, 3 Nov 2015 21:22:30 +0100 MIME-Version: 1.0 In-Reply-To: <1446580695-28525-1-git-send-email-ehabkost@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 0/3] target-i386: Don't trigger CPUID warnings by default in KVM mode (in most hosts) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost , qemu-devel@nongnu.org Cc: Igor Mammedov , "Michael S. Tsirkin" , "Dr. David Alan Gilbert" , Richard Henderson On 03/11/2015 20:58, Eduardo Habkost wrote: > The x86 change to make "check" mode be enabled by default made QEMU print > warnings in the default case if running in an Intel host: > > $ qemu-system-x86_64 -machine pc,accel=kvm > warning: host doesn't support requested feature: CPUID.80000001H:ECX.sse4a [bit 6] > > There's also a warning when about missing the ABM feature if running on a Sandy > Bridge or older host. > > ABM is not available on Sandy Bridge and older, SSE4a is not available in any > Intel host. We want to make the default CPU runnable in most hosts, so those > features won't be enabled by default in KVM mode. > > We should eventually have all features supported by TCG enabled by default in > TCG mode, but as we don't have a good mechanism today to ensure we have > different defaults in KVM and TCG mode, disable ABM and SSE4a in the qemu64 CPU > model entirely. > > Also, as we can't change the guest ABI in pc-*-2.4, disable "check" mode by > default in pc-*-2.4 and older so we don't print spurious warnings. > > Note that with this change, the qemu64 CPU model still requires a host > supporting POPCNT (Nehalem or newer, and Opteron_G3 or newer). Do we want to remove that one as well? > Eduardo Habkost (3): > target-i386: Set "check=off" by default on pc-*-2.4 and older > target-i386: Remove SSE4a from qemu64 CPU model > target-i386: Remove ABM from qemu64 CPU model > > include/hw/i386/pc.h | 15 +++++++++++++++ > target-i386/cpu.c | 3 +-- > 2 files changed, 16 insertions(+), 2 deletions(-) > In any case, Reviewed-by: Paolo Bonzini Paolo