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,UNPARSEABLE_RELAY 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 9F171C433E0 for ; Wed, 20 Jan 2021 10:19:47 +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 0932C23330 for ; Wed, 20 Jan 2021 10:19:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0932C23330 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=dme.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34288 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2AaY-0000Ym-1I for qemu-devel@archiver.kernel.org; Wed, 20 Jan 2021 05:19:46 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33696) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l2AYX-0007ar-Aj for qemu-devel@nongnu.org; Wed, 20 Jan 2021 05:17:42 -0500 Received: from mail-wm1-x333.google.com ([2a00:1450:4864:20::333]:36733) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1l2AYV-0005Xy-EN for qemu-devel@nongnu.org; Wed, 20 Jan 2021 05:17:40 -0500 Received: by mail-wm1-x333.google.com with SMTP id v184so2326748wma.1 for ; Wed, 20 Jan 2021 02:17:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dme-org.20150623.gappssmtp.com; s=20150623; h=to:cc:subject:in-reply-to:references:from:date:message-id :mime-version:content-transfer-encoding; bh=/HkiBvoVdZIJrEzSBhimQMSj69Zur+6MeKP45Dw7C+4=; b=04udrIMQEUCn+LV7lpovSHz86Xa5bR8HWH9qa1Fw7WQBhVjh0exPCN1c9qsrmp/20M WkgehbzmDfGYLtuDit1cgvuXnNH2se5LBjwq0E5h1wyFH5p/TXCCApIswYU4aLomSACh EScLZOMizgOVGcwouZkcgIMt8I/PtJRnHw/6w9z8HDI2TTpX9pKHYj6Zf0vmz9jCB2OV ankWfuqR9YePjaLaJ/4y0MtHRcNh1pWlMbSeh3Efg9E354qr/V4Q3/BzCOMcNyKrFLNg vT2ORaD8U38sC5QaVU1iXd6JXPC5/Q9xqx92wMqstCJCwYrbfE8/e3CsTwTHSmehzhus BYqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:subject:in-reply-to:references:from:date :message-id:mime-version:content-transfer-encoding; bh=/HkiBvoVdZIJrEzSBhimQMSj69Zur+6MeKP45Dw7C+4=; b=EcF3EqNaU8PMcww+zKUA6IDIP87AvwrIqCEZ6DFHIcHx3WX2rD48UrZt6Zf9YXd0ny r6YDLWXqVwqvDD+w2d5xnTWORqpYSHrIbVkECfa9JYz0z+EhZRFd8pMSgCebvb6bWSio Br5lcOSSx8pvwx8Wm4fQaKk0sQSL5LY9OiXPuDQJXJiW+sinEnh0ir/Eo+7IQ1wdBU0N VYFY0ItLbMkqTlvjxnLvWLd0YMwdXZH+engYGawW11uO4fdgOlg3vlH2/8S9fSm0wm6R j6VSYwkTJEYw1Xl3uAHDlidSwmeLDOEry7RtlSmX4+fNPYeDgUUClL1QAoBOeoJXKlXC 23xw== X-Gm-Message-State: AOAM533vhhdofUMWWxv5xYjX+qZsX0nV3NXw8e8dmbImn8CNDMkedJHl RjEyNt2K8H+bb8To7NQg/1bB1Q== X-Google-Smtp-Source: ABdhPJw4f1hLG4zTb7nyJJE9o/odNPPLmrrCJwxZDF4XtHSY9haqsyGtrTTKvvMm6xqAxK35bI/59w== X-Received: by 2002:a1c:ac86:: with SMTP id v128mr3592648wme.76.1611137857996; Wed, 20 Jan 2021 02:17:37 -0800 (PST) Received: from disaster-area.hh.sledj.net (disaster-area.hh.sledj.net. [2001:8b0:bb71:7140:64::1]) by smtp.gmail.com with ESMTPSA id v6sm2717189wrx.32.2021.01.20.02.17.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Jan 2021 02:17:37 -0800 (PST) Received: from localhost (disaster-area.hh.sledj.net [local]) by disaster-area.hh.sledj.net (OpenSMTPD) with ESMTPA id d9b0d2fd; Wed, 20 Jan 2021 10:17:36 +0000 (UTC) To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Eduardo Habkost Subject: Re: [RFC PATCH 1/2] hw/i386: -cpu model,-feature,+feature should enable feature In-Reply-To: <20210120100803.GF3015589@redhat.com> 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> X-HGTTG: zarquon From: David Edmondson X-Now-Playing: Four Tet - Sixteen Oceans: 1993 Band Practice Date: Wed, 20 Jan 2021 10:17:36 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: neutral client-ip=2a00:1450:4864:20::333; envelope-from=dme@dme.org; helo=mail-wm1-x333.google.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NEUTRAL=0.779, UNPARSEABLE_RELAY=0.001 autolearn=no 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 , "Michael S. Tsirkin" , Richard Henderson , qemu-devel@nongnu.org, Igor Mammedov , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wednesday, 2021-01-20 at 10:08:03 GMT, Daniel P. Berrang=C3=A9 wrote: > On Tue, Jan 19, 2021 at 11:30:52AM -0500, Eduardo Habkost wrote: >> On Tue, Jan 19, 2021 at 04:27:56PM +0000, David Edmondson wrote: >> > 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: >> > >> "Minus" features are applied after "plus" features, so ensure that a >> > >> later "plus" feature causes an earlier "minus" feature to be remove= d. >> > >>=20 >> > >> This has no effect on the existing "-feature,feature=3Don" backward >> > >> compatibility code (which warns and turns the feature off). >> > > >> > > If we are changing behavior, why not change behavior of >> > > "-feature,feature=3Don" at the same time? This would allow us to >> > > get rid of plus_features/minus_features completely and just make >> > > +feature/-feature synonyms to feature=3Don/feature=3Doff. >> >=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. what th= is >> > patch does) Really: can this just be changed, or does there have to be >> > some period where the behaviour stays the same with a warning? >>=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? > > Where are you expecting warnings ? I don't see any when launching QEMU qemu-system-x86_64 -display none -cpu Westmere,-vmx,+vmx Warnings because the result of this is "-vmx". > IMHO just leave the parsing unchanged, deprecate it, and then delete > the code. We don't need to "improve" usability semantics of something > that we want to delete anyway. /me nods. dme. --=20 I just bite it, it's for the look I don't light it.