From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56140) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtDQb-000561-Eq for qemu-devel@nongnu.org; Mon, 02 Nov 2015 06:37:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZtDQW-0005UV-Br for qemu-devel@nongnu.org; Mon, 02 Nov 2015 06:37:33 -0500 Received: from mail-wi0-x22e.google.com ([2a00:1450:400c:c05::22e]:34037) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtDQW-0005UR-55 for qemu-devel@nongnu.org; Mon, 02 Nov 2015 06:37:28 -0500 Received: by wikq8 with SMTP id q8so49446711wik.1 for ; Mon, 02 Nov 2015 03:37:27 -0800 (PST) Sender: Paolo Bonzini References: <1446231660-24394-1-git-send-email-ehabkost@redhat.com> <20151030191323.GA20436@thinpad.lan.raisama.net> From: Paolo Bonzini Message-ID: <56374AF4.5070406@redhat.com> Date: Mon, 2 Nov 2015 12:37:24 +0100 MIME-Version: 1.0 In-Reply-To: <20151030191323.GA20436@thinpad.lan.raisama.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/3] target-i386: Don't trigger "check" warnings by default in KVM mode 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" , Richard Henderson On 30/10/2015 20:13, Eduardo Habkost wrote: > On Fri, Oct 30, 2015 at 05:00:57PM -0200, Eduardo Habkost wrote: >> The x86 change to make "check" mode be enabled by default made QEMU print a >> warning 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] >> >> Fix this by not enabling sse4a in qemu64 when in KVM mode. >> >> The long term solution will probably involve creating separate "tcg64" and >> "kvm64" CPU models as defaults, so we can finally choose completely diffferent >> defaults in the KVM- and TCG-specific models without making the >> kvm_default_props list grow too mcuh. > > Note that we can have a much simpler solution to this: disabling SSE4A > on qemu64 completely, even on TCG. This way we can use PC_COMPAT_2_4 > instead of the kvm_default_props compat hack. > > We can reenable SSE4A for TCG later (more exactly, we could enable > everything from TCG_*_FEATURES) when we implement the kvm64/tcg64 > solution. > > What do you think? I would prefer that to this series. Another possibility (even more of a hack, but perhaps acceptable) is to disable SSE4A in x86_cpu_load_def if kvm_enabled() and the host vendor is not AMD. This is effectively what was already happening in 2.4 and earlier. Paolo