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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,T_HK_NAME_DR,URIBL_BLOCKED,USER_AGENT_MUTT 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 C6187C04E53 for ; Wed, 15 May 2019 11:10:01 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9339C20881 for ; Wed, 15 May 2019 11:10:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9339C20881 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 ([127.0.0.1]:35280 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQrnM-0002IA-TD for qemu-devel@archiver.kernel.org; Wed, 15 May 2019 07:10:00 -0400 Received: from eggs.gnu.org ([209.51.188.92]:46465) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQrmc-0001v3-IT for qemu-devel@nongnu.org; Wed, 15 May 2019 07:09:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hQrmb-0005z7-Hr for qemu-devel@nongnu.org; Wed, 15 May 2019 07:09:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35642) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hQrmb-0005wW-6g for qemu-devel@nongnu.org; Wed, 15 May 2019 07:09:13 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BFAB830089B6; Wed, 15 May 2019 11:09:11 +0000 (UTC) Received: from work-vm (ovpn-117-193.ams2.redhat.com [10.36.117.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7879C5D70A; Wed, 15 May 2019 11:09:06 +0000 (UTC) Date: Wed, 15 May 2019 12:09:04 +0100 From: "Dr. David Alan Gilbert" To: Dave Martin Message-ID: <20190515110903.GG2668@work-vm> References: <20190418092841.fzrcegkbal7dpfcy@kamzik.brq.redhat.com> <20190418112610.GO13773@redhat.com> <877ebrmch2.fsf@dusky.pond.sub.org> <20190513184237.i2ha3ixvhjqzkn5q@kamzik.brq.redhat.com> <87bm05ab6c.fsf@dusky.pond.sub.org> <20190514090225.vel4xm4x743o4rge@kamzik.brq.redhat.com> <20190514164838.48fc7603@Igors-MacBook-Pro> <20190515081854.kcpjm4zd2bzc7f6o@kamzik.brq.redhat.com> <20190515110045.GQ28398@e103592.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190515110045.GQ28398@e103592.cambridge.arm.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 15 May 2019 11:09:11 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] How do we do user input bitmap properties? X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "peter.maydell@linaro.org" , Andrew Jones , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , "qemu-devel@nongnu.org" , Markus Armbruster , Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Dave Martin (Dave.Martin@arm.com) wrote: > On Wed, May 15, 2019 at 09:18:54AM +0100, Andrew Jones wrote: > > On Tue, May 14, 2019 at 04:48:38PM +0200, Igor Mammedov wrote: > > > On Tue, 14 May 2019 11:02:25 +0200 > > > Andrew Jones wrote: > > > > My thought is primarily machines. If a human wants to use the command > > > > line and SVE, then I'm assuming they'll be happy with sve-max-vq or > > > > figuring out a map they like once and then sticking to it. > > > > > > maybe naive question, but why not use a property/bit as user facing interface, > > > in line with what we do with CPUID bits. (that's assuming that bits have > > > fixed meaning). > > > Yes, it's verbose but follows current practice and works fine with -cpu and > > > -device. > > > (I really hate custom preprocessing of -cpu and we were working hard to remove > > > that in favor of canonical properties at the expense of more verbose CLI). > > > > > > > Are you asking if we should do something like the following? > > > > -cpu host,sve1=on,sve=2=on,sve3=off,sve4=on > > Note, there is nothing SVE-specific about this. > > Either enabling features on a per-vcpu basis is justified, or it isn't: > if it's justified, then it would be better to have a general way of > specifying per-vcpu properties, rather than it being reinvented per > feature. SVE *is* a bit unusual. In most CPU features they're actually features, they're on or off, so we have a big list of features that are enabled/disabled. We've had that type of thing (at least on x86) for years and it's OK. We've got one or two things where they're numerical (e.g. host-physbits) and we struggle a bit with how to handle them. SVE is somewhere in between - it's a list of numbers, apparently a fairly large arbitrarily set of numbers that could be chosen so you'd need lots of feature flags (sve1...sve64 say or more); so that doesn't fit the existing things we've had that have worked. Dave > Creating mismatched configurations is allowed by the architecture and so > it's useful for testing the kernel, but probably less useful for real- > world use cases today. > > So it may be a good idea to get the symmetric support sorted out first > before thinking about whether and how to specify asymmetric > configurations. > > Cheers > ---Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK