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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 F0BB1C33CAA for ; Tue, 21 Jan 2020 05:43:58 +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 B663922522 for ; Tue, 21 Jan 2020 05:43:58 +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="VBMNSPZJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B663922522 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]:48640 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1itmKT-0007kF-VP for qemu-devel@archiver.kernel.org; Tue, 21 Jan 2020 00:43:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39138) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1itmJe-0007GE-MD for qemu-devel@nongnu.org; Tue, 21 Jan 2020 00:43:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1itmJd-0008Op-Ig for qemu-devel@nongnu.org; Tue, 21 Jan 2020 00:43:06 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:39720 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1itmJd-0008OV-FH for qemu-devel@nongnu.org; Tue, 21 Jan 2020 00:43:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579585384; 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=ke6kdANLkx+TogH4Xqrewy892//8qh6EzCqpSTQVWPE=; b=VBMNSPZJGhz7YqW8vDlb800agbXA/xbbE2GoEPja3Y5a4874gJUxa1KZpVeRjyuTjxAD6W SE9/oeVrLOzS72+Xm2CJBSptuji0pLId6xuRuNmw1eoP0Zl88GOrBCdxAQbLgfoVPHtihj HjJoJo6EM1dfKq7JRUy4cPbeT0MkiDg= 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-236-Cw9DBNv4MJKNQ-gScUsuUg-1; Tue, 21 Jan 2020 00:43:01 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id B280218A6EC1; Tue, 21 Jan 2020 05:43:00 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-131.ams2.redhat.com [10.36.116.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F194C89E9D; Tue, 21 Jan 2020 05:42:48 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 87CA41138600; Tue, 21 Jan 2020 06:42:47 +0100 (CET) From: Markus Armbruster To: Stefan Hajnoczi Subject: Re: Making QEMU easier for management tools and applications 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> <20200120100849.GB345995@stefanha-x1.localdomain> Date: Tue, 21 Jan 2020 06:42:47 +0100 In-Reply-To: <20200120100849.GB345995@stefanha-x1.localdomain> (Stefan Hajnoczi's message of "Mon, 20 Jan 2020 10:08:49 +0000") Message-ID: <871rrtmkko.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: Cw9DBNv4MJKNQ-gScUsuUg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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: Kevin Wolf , Peter Maydell , "Daniel P. Berrange" , "Denis V. Lunev" , qemu-devel , Paolo Bonzini , Christophe de Dinechin , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , John Snow , Dominik Csapak Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Stefan Hajnoczi writes: > On Wed, Jan 15, 2020 at 01:15:17PM +0100, Markus Armbruster wrote: >> Christophe de Dinechin writes: >> >> On 15 Jan 2020, at 10:20, Markus Armbruster wrote= : >> * 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. > > I'm happy to use a different interface. > > Writing a boilerplate "iothread-set-poll-params" QMP command in C would > be a step backwards. No argument. > Maybe the QAPI code generator could map something like this: > > { 'command': 'iothread-set-poll-params', > 'data': { > 'id': 'str', > =09'*max-ns': 'uint64', > =09'*grow': 'uint64', > =09'*shrink': 'uint64' > }, > 'map-to-qom-set': 'IOThread' > } > > And turn it into QOM accessors on the IOThread object. I think a generic "set this configuration to that value" command is just fine. qom-set fails on several counts, though: * Tolerable: qom-set is not actually generic, it applies only to QOM. * qom-set lets you set tons of stuff that is not meant to be changed at run time. If it breaks your guest, you get to keep the pieces. * There is virtually no documentation on what can be set to what values, and their semantics. In its current state, QOM is a user interface superfund site.