From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04D23C47404 for ; Sat, 12 Oct 2019 02:06:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CCADB20679 for ; Sat, 12 Oct 2019 02:06:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCADB20679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:58260 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iJ6nf-00053F-S8 for qemu-devel@archiver.kernel.org; Fri, 11 Oct 2019 22:06:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52859) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iJ6mt-0004b9-MS for qemu-devel@nongnu.org; Fri, 11 Oct 2019 22:05:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iJ6mr-0001ss-5k for qemu-devel@nongnu.org; Fri, 11 Oct 2019 22:05:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46748) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iJ6mq-0001sN-Hy for qemu-devel@nongnu.org; Fri, 11 Oct 2019 22:05:41 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B8D6DC05AA63; Sat, 12 Oct 2019 02:05:38 +0000 (UTC) Received: from localhost (ovpn-116-20.phx2.redhat.com [10.3.116.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id E9A336092F; Sat, 12 Oct 2019 02:05:35 +0000 (UTC) Date: Fri, 11 Oct 2019 23:05:34 -0300 From: Eduardo Habkost To: Xiaoyao Li Subject: Re: [PATCH v2] target/i386: Add Snowridge-v2 (noMPX) CPU model Message-ID: <20191012020534.GA10330@habkost.net> References: <20191011145349.123425-1-xiaoyao.li@intel.com> <20191011182143.GD4084@habkost.net> <20191012012134.GJ4084@habkost.net> <89f3f389-372e-e758-27dc-64aa165fd57c@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89f3f389-372e-e758-27dc-64aa165fd57c@intel.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Sat, 12 Oct 2019 02:05:38 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, Oct 12, 2019 at 09:31:25AM +0800, Xiaoyao Li wrote: > On 10/12/2019 9:21 AM, Eduardo Habkost wrote: > > On Sat, Oct 12, 2019 at 09:15:56AM +0800, Xiaoyao Li wrote: > > > On 10/12/2019 2:21 AM, Eduardo Habkost wrote: > > > > On Fri, Oct 11, 2019 at 10:53:49PM +0800, Xiaoyao Li wrote: > > > > > Add new version of Snowridge CPU model that removes MPX feature. > > > > > > > > > > MPX support is being phased out by Intel. GCC has dropped it, Linux kernel > > > > > and kvm are also going to do that in the future. > > > > > > > > > > Signed-off-by: Xiaoyao Li > > > > > --- > > > > > Changes in v2: > > > > > - Use CPU model versioning mechanism instead of machine-type compat > > > > > --- > > > > > target/i386/cpu.c | 13 +++++++++++++ > > > > > 1 file changed, 13 insertions(+) > > > > > > > > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > > > > index 44f1bbdcac76..27b0a17b46a8 100644 > > > > > --- a/target/i386/cpu.c > > > > > +++ b/target/i386/cpu.c > > > > > @@ -2793,6 +2793,19 @@ static X86CPUDefinition builtin_x86_defs[] = { > > > > > CPUID_6_EAX_ARAT, > > > > > .xlevel = 0x80000008, > > > > > .model_id = "Intel Atom Processor (SnowRidge)", > > > > > + .versions = (X86CPUVersionDefinition[]) { > > > > > + { .version = 1 }, > > > > > + { > > > > > + .version = 2, > > > > > + .alias = "Snowridge-noMPX", > > > > > > > > The intention is to stop creating new funny names for CPU model > > > > variations, now, and stick to -v1, -v2, -v3, etc. > > > > > > > > The .alias field is optional, and was added only for > > > > compatibility with the existing -noTSX and -IBRS CPU models. > > > > > > Got it. > > > > > > > > + .props = (PropValue[]) { > > > > > + { "mpx", "off" }, > > > > > + { "model-id", "Intel Atom Processor (Snowridge, no MPX)" }, > > > > > > > > Do you think it's important to report a different model-id? > > > > I would keep it the same and only add mpx=off. > > > > > > I just want to let user know easily the differences between Snowridge-v1 and > > > Snowridge-v2. Unfortunately, it seems ugly. > > > > > > When testing with Cascadelake-Server, it puzzles every time that which one > > > should I choose between Cascadelake-Server-v1 and Cascadelake-Server-v2. > > > From the output of "-cpu ?", I don't know the differences between them. > > > Everytime I have to go to the source code to see the difference. > > > > > > Maybe there is a way to see/report the differences between different > > > versions of the same CPU model that I just don't know? > > > > Good point. I forgot that model-id is also the model description > > in "-cpu ?". > > > > Well, it doesn't hurt to have a different model-id in v2 that's > > more informative. Feel free to keep the model-id line in v3. > > OK. I will send out the v3 patch keeping the model-id while removing the > alias. > > BTW, do you have better idea to tell the differences among versions of the > same CPU model? We could add a new field for a human-readable description of the CPU model version, and print that field on "-cpu help" if set. We could also try to generate a description automatically (e.g. automatically describe SnowRidge-v2 as "SnowRidge-v1 plus mpx" based on .props). I'm not sure if it would be worth the effort, though. -- Eduardo