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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 2D616C33CB1 for ; Wed, 15 Jan 2020 12:21:06 +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 A08C3207FF for ; Wed, 15 Jan 2020 12:21:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Qm5iZjQ0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A08C3207FF 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]:52914 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1irhfU-0005Il-QI for qemu-devel@archiver.kernel.org; Wed, 15 Jan 2020 07:21:04 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:47044) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1irhei-0004iM-5S for qemu-devel@nongnu.org; Wed, 15 Jan 2020 07:20:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1irhee-0008Sy-C6 for qemu-devel@nongnu.org; Wed, 15 Jan 2020 07:20:16 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:40413 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1irhee-0008Sd-7g for qemu-devel@nongnu.org; Wed, 15 Jan 2020 07:20:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579090811; h=from:from:reply-to: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=yEN8dSEuhiZ8ohF4PsSGipeAt7RCTuACNkUFg8l8jdA=; b=Qm5iZjQ0GUIPXy9Y2N4ddnOXArW7xgBLJzvglv2himaRt6KzcBnaJk8RGcN8/0Lhkxf83o tmYZeJKC1jLB21Ij9h2aSaTnctTqCjH8fmPHU1e5GRA+buoSjmQ6n8OQeWm9k0vRjm+6B8 N9uHH3eu3wF3B9ysRfEzOE9Q6ZA8cPw= 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-377-BhYNqpzlNiOIqbQKbzsipQ-1; Wed, 15 Jan 2020 07:20:08 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EF7CD1081FD7; Wed, 15 Jan 2020 12:20:06 +0000 (UTC) Received: from redhat.com (ovpn-112-60.ams2.redhat.com [10.36.112.60]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1C9FD19757; Wed, 15 Jan 2020 12:19:55 +0000 (UTC) Date: Wed, 15 Jan 2020 12:19:53 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: Making QEMU easier for management tools and applications Message-ID: <20200115121953.GJ93923@redhat.com> References: <1EFEF446-AFEA-429F-B6BA-3206A7C41836@redhat.com> <20200108104306.GC5057@dhcp-200-226.str.redhat.com> <97F153BD-FB8A-46C7-90D0-9E894B9E0292@redhat.com> <20200108133842.GE5057@dhcp-200-226.str.redhat.com> <87d0bmchq0.fsf@dusky.pond.sub.org> <1B253197-5592-472A-AA26-E0614A13C91A@redhat.com> <87o8v52hz9.fsf@dusky.pond.sub.org> <8CF8359B-1E52-4F7A-944E-C1C14FEC4F92@redhat.com> <87r200zzje.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87r200zzje.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: BhYNqpzlNiOIqbQKbzsipQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , Peter Maydell , "Denis V. Lunev" , Stefan Hajnoczi , qemu-devel , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Christophe de Dinechin , Paolo Bonzini , John Snow , Dominik Csapak Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jan 15, 2020 at 01:15:17PM +0100, Markus Armbruster wrote: > Christophe de Dinechin writes: >=20 > > Thanks a bunch. This clarifies a number of my misconceptions about > > how this is currently used. Most notably this one: > > > >> On 15 Jan 2020, at 10:20, Markus Armbruster wrote: > >>=20 > >>> We don=E2=80=99t want the QAPI to let arbitrary fields of a QOM objec= t > >>> be modified, do we? > >>=20 > >> We already do: QMP command qom-set. If it breaks your guest, you get = to > >> keep the pieces. > > > > Ouch. I certainly did not expect that. > > > > "It is not what you don=E2=80=99t know that kills you, it is what you k= now that ain=E2=80=99t so". >=20 > Do we have a legitimate use for qom-set right now? Hmm, let's check > libvirt... aha: >=20 > * qemuMonitorJSONSetMemoryStatsPeriod() uses it to control > virtio-balloon's guest-stats-polling-interval property, in accordance > with docs/virtio-balloon-stats.txt. >=20 > * qemuMonitorJSONSetIOThread() uses it to control iothread's properties > poll-max-ns, poll-grow, poll-shrink. Their use with -object is > documented (in qemu-options.hx), their use with qom-set is not. >=20 > Oh well. Libvirt is of course happy to switch to something else instead of qom-set for these features if QEMU wants to provide a safer alternative. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberrange= :| |: https://libvirt.org -o- https://fstop138.berrange.com= :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange= :|