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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 DF2A0C433E0 for ; Wed, 20 Jan 2021 19:26:16 +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 1AD12233EB for ; Wed, 20 Jan 2021 19:26:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1AD12233EB 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]:56096 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2J7P-0007Ju-3I for qemu-devel@archiver.kernel.org; Wed, 20 Jan 2021 14:26:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:45716) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l2J3K-0005Vb-C7 for qemu-devel@nongnu.org; Wed, 20 Jan 2021 14:22:02 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:58110) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l2J3G-00014I-Ey for qemu-devel@nongnu.org; Wed, 20 Jan 2021 14:22:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611170517; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BSCpKHfLAydbAnxQl7cCLwAXEcfsqT2AFdr9/w+ijC4=; b=bUBwkq4AGCbuYsg1lfky1vVL6Dp1z5YY1/t2arhMYaw8qwJ9ZkriKYPJCkoRet+9q1XWQL ldlxNj6ZiqGEaU2GD4hJcqw74U/pfTdUdmjszAduHh8Ws/lOBW4uCPzLNcpRCWykMKwHxA 9vIc3jZrmnTcgvbrwXdHmXMC0AJm33c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-64-27bHl-YyMP-fOdKcWJOt4Q-1; Wed, 20 Jan 2021 14:21:43 -0500 X-MC-Unique: 27bHl-YyMP-fOdKcWJOt4Q-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 25502107ACE3; Wed, 20 Jan 2021 19:21:42 +0000 (UTC) Received: from localhost (unknown [10.40.208.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id BB8BD71C85; Wed, 20 Jan 2021 19:21:36 +0000 (UTC) Date: Wed, 20 Jan 2021 20:21:34 +0100 From: Igor Mammedov To: Eduardo Habkost Subject: Re: [RFC PATCH 1/2] hw/i386: -cpu model,-feature,+feature should enable feature Message-ID: <20210120202134.4e0c4523@redhat.com> In-Reply-To: <20210120161801.GP1227584@habkost.net> References: <20210119142207.3443123-1-david.edmondson@oracle.com> <20210119142207.3443123-2-david.edmondson@oracle.com> <20210119152056.GE1227584@habkost.net> <20210119163052.GG1227584@habkost.net> <20210120100803.GF3015589@redhat.com> <20210120161801.GP1227584@habkost.net> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=63.128.21.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.167, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Laurent Vivier , Thomas Huth , "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" , "Michael S. Tsirkin" , David Edmondson , Richard Henderson , qemu-devel@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 20 Jan 2021 11:18:01 -0500 Eduardo Habkost wrote: > On Wed, Jan 20, 2021 at 10:17:36AM +0000, David Edmondson wrote: > > On Wednesday, 2021-01-20 at 10:08:03 GMT, Daniel P. Berrang=C3=A9 wrote= : > > =20 > > > On Tue, Jan 19, 2021 at 11:30:52AM -0500, Eduardo Habkost wrote: =20 > > >> On Tue, Jan 19, 2021 at 04:27:56PM +0000, David Edmondson wrote: =20 > > >> > On Tuesday, 2021-01-19 at 10:20:56 -05, Eduardo Habkost wrote: > > >> > =20 > > >> > > Hi, > > >> > > > > >> > > Thanks for the patch. Getting rid of special -feature/+feature > > >> > > behavior was in our TODO list for a long time. > > >> > > > > >> > > On Tue, Jan 19, 2021 at 02:22:06PM +0000, David Edmondson wrote:= =20 > > >> > >> "Minus" features are applied after "plus" features, so ensure t= hat a > > >> > >> later "plus" feature causes an earlier "minus" feature to be re= moved. > > >> > >>=20 > > >> > >> This has no effect on the existing "-feature,feature=3Don" back= ward > > >> > >> compatibility code (which warns and turns the feature off). =20 > > >> > > > > >> > > If we are changing behavior, why not change behavior of > > >> > > "-feature,feature=3Don" at the same time? This would allow us t= o > > >> > > get rid of plus_features/minus_features completely and just make > > >> > > +feature/-feature synonyms to feature=3Don/feature=3Doff. =20 > > >> >=20 > > >> > Okay, I'll do that. > > >> >=20 > > >> > Given that there have been warnings associated with > > >> > "-feature,feature=3Don" for a while, changing that behaviour seems > > >> > acceptable. > > >> >=20 > > >> > Would the same be true for changing "-feature,+feature"? (i.e. wha= t this > > >> > patch does) Really: can this just be changed, or does there have t= o be > > >> > some period where the behaviour stays the same with a warning? =20 > > >>=20 > > >> I actually expected warnings to be triggered when using > > >> "-feature,+feature" as well. If we were not generating warnings > > >> for that case, it will need more careful evaluation, just to be > > >> sure it's safe. Igor, do you remember the details here? =20 > > > > > > Where are you expecting warnings ? I don't see any when launching QEM= U =20 > >=20 > > qemu-system-x86_64 -display none -cpu Westmere,-vmx,+vmx > >=20 > > Warnings because the result of this is "-vmx". > > =20 > > > IMHO just leave the parsing unchanged, deprecate it, and then delete > > > the code. We don't need to "improve" usability semantics of somethin= g > > > that we want to delete anyway. =20 > >=20 > > /me nods. =20 >=20 > I agree, but I guess we need to convince Paolo: > https://lore.kernel.org/qemu-devel/1990888058.22417362.1465939000140.Java= Mail.zimbra@redhat.com/ that's ancient :) He recently started this revolution himself :) https://www.mail-archive.com/qemu-devel@nongnu.org/msg757280.html That's why I have -cpu +/-foo deprecation on my not too far away TODO list.