From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35805) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gZzKv-000770-2j for qemu-devel@nongnu.org; Thu, 20 Dec 2018 09:30:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gZzGH-0008O3-Dz for qemu-devel@nongnu.org; Thu, 20 Dec 2018 09:25:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51712) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gZzGG-0008MS-UP for qemu-devel@nongnu.org; Thu, 20 Dec 2018 09:25:17 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A9C2789AE3 for ; Thu, 20 Dec 2018 14:25:15 +0000 (UTC) References: <20181220121100.21554-1-pbonzini@redhat.com> <490cbc41-0076-659a-9745-29881b9c95cc@redhat.com> From: Paolo Bonzini Message-ID: <9685dcbe-7236-c03d-47e9-9b1eb30d9a3c@redhat.com> Date: Thu, 20 Dec 2018 15:25:02 +0100 MIME-Version: 1.0 In-Reply-To: <490cbc41-0076-659a-9745-29881b9c95cc@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] target/i386: Disable MPX support on named CPU models List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wainer dos Santos Moschetta , qemu-devel@nongnu.org Cc: ehabkost@redhat.com On 20/12/18 15:18, Wainer dos Santos Moschetta wrote: >=20 > On 12/20/2018 10:11 AM, Paolo Bonzini wrote: >> MPX support is being phased out by Intel; GCC has dropped it, Linux >> is also going to do that.=C2=A0 Even though KVM will have special code >> to support MPX after the kernel proper stops enabling it in XCR0, >> we probably also want to deprecate that in a few years.=C2=A0 As a sta= rt, >> do not enable it by default for any named CPU model starting with >> the 4.0 machine types; this include Skylake, Icelake and Cascadelake. >> >> Signed-off-by: Paolo Bonzini >> --- >> =C2=A0 include/hw/i386/pc.h | 29 +++++++++++++++++++++++++++++ >> =C2=A0 target/i386/cpu.c=C2=A0=C2=A0=C2=A0 | 14 +++++++------- >> =C2=A0 2 files changed, 36 insertions(+), 7 deletions(-) >=20 > Side question: I didn't find on QEMU's user manual any reference to > deprecated features for CPU models. Does that information exists > somewhere? If not, should it be documented for the users? It's not deprecated yet, as it won't be removed until pc-*-3.1 is deprecated. It may be deprecated together with pc-*-3.1, or maybe not since TCG does implement MPX. Paolo