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 A65CCC33CAA for ; Thu, 23 Jan 2020 07:38:27 +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 70E2624125 for ; Thu, 23 Jan 2020 07:38:27 +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="OeyiVGmZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 70E2624125 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]:52286 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iuX4M-000139-Jd for qemu-devel@archiver.kernel.org; Thu, 23 Jan 2020 02:38:26 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:43247) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iuX3Q-0000Zf-9I for qemu-devel@nongnu.org; Thu, 23 Jan 2020 02:37:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iuX3N-0001f1-O9 for qemu-devel@nongnu.org; Thu, 23 Jan 2020 02:37:27 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:35910 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 1iuX3N-0001eO-K8 for qemu-devel@nongnu.org; Thu, 23 Jan 2020 02:37:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579765044; 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=BOF87p7w1HWP1UCZobH0sFRKSoW6878YVTG/S6KvZd0=; b=OeyiVGmZE9pNS0/YfzpamfdTSZynhHWfO8N9u4Ac+pz8yFdzeVxLHvq66+mwnJ+DcygzrV r5LOjsIqDlXva/9EvAGo50kAwFyimLJFiM7GugVuF2lA1LfqdiGinj3K0kmbZGE2dHxG81 ZxmOp7blB3UdPltNp/1kZ7BSfZJmnnE= 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-238-IzZFNyqGP9SUN0XeD61tSQ-1; Thu, 23 Jan 2020 02:37:22 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F83D107ACCA; Thu, 23 Jan 2020 07:37:21 +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 5B6D85DA7C; Thu, 23 Jan 2020 07:37:16 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id DF67E1138600; Thu, 23 Jan 2020 08:37:14 +0100 (CET) From: Markus Armbruster To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Subject: Re: Integrating QOM into QAPI References: <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> <871rrtmkko.fsf@dusky.pond.sub.org> <20200121113224.GD630615@stefanha-x1.localdomain> <87wo9lc4oe.fsf_-_@dusky.pond.sub.org> <20200121143658.GB597037@redhat.com> <871rrs97ld.fsf@dusky.pond.sub.org> <87y2tzzrwo.fsf@linaro.org> <87wo9ju19n.fsf@dusky.pond.sub.org> Date: Thu, 23 Jan 2020 08:37:14 +0100 In-Reply-To: (=?utf-8?Q?=22Marc-Andr=C3=A9?= Lureau"'s message of "Wed, 22 Jan 2020 16:42:13 +0400") Message-ID: <87lfpyd3o5.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 10.5.11.14 X-MC-Unique: IzZFNyqGP9SUN0XeD61tSQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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. =?utf-8?Q?Berrang=C3=A9?=" , "Denis V. Lunev" , Stefan Hajnoczi , QEMU , Alex =?utf-8?Q?Benn=C3=A9e?= , Christophe de Dinechin , Paolo Bonzini , John Snow , Dominik Csapak Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Marc-Andr=C3=A9 Lureau writes: > Hi > > On Wed, Jan 22, 2020 at 4:25 PM Markus Armbruster wro= te: >> >> Alex Benn=C3=A9e writes: >> >> > Marc-Andr=C3=A9 Lureau writes: >> >> Actually, we are not that far off from being able to use GObject >> >> altogether (I hacked something like that to play with), but I >> >> disgress... >> > >> > As a mostly hands off observer who mainly c&p's QOM code when he has t= o >> > I have to ask is this a long term plan? >> > >> > I've always found having our own hand rolled object system a little >> > incongruous given we lean heavily on the rest of glib. >> >> I vaguely remember claims that GObject falls short of our needs. Sadly, >> I don't remember the details. This is why major features should come >> with a design document. >> >> https://wiki.qemu.org/Features/QOM ain't: it does not mention GObject. >> I'm afraid that page has fallen too far behind the code to be useful to >> anyone not familiar with the code. > >>>From the top of my mind, this is the pain point when trying to use GObjec= t: > - static/inlined object, not supported by GObject, unlikely to ever be Lame. Okay for us as long as the pointer chasing stays off the hot paths. But that's not obvious. > - few users in qemu, transition possible. Peter challenged this idea. > - 64k limit of GObject, for some reason, unlikely to change but I will > take a look. Some users in qemu, code adaptation possible. Also lame. I figure code adaption will involve pointer chasing. Again, beware of hot paths. This one feels less likely to be a problem, though. > - dynamic properties, possible in GObject with hacks, but not > recommended and going to be deprecated from what I remember Never understood our need for them for longer than half a day after getting it explained to me. I guess that's my fault. Anyway, the less we use them, the better. Hacks exploiting deprecated GObject features would be a bad idea. Perhaps we can hack something up that doesn't. > - "array" properties - would need extra layer/tweaks for compatibility I hated them from day one, tried to kill them, lost the argument. > - link properties - would need special handling Hard or not? > - different limitations for type names and properties names What to do? Our naming rules and conventions are weakly documented. > A possible initial approach is to have all the type system and object > allocation done by GObject under the hood (what I hacked), while > keeping all the properties handled by QOM. Then, figure out a > migration to GObject properties (which are also being refactored a bit > upstream). So most QOM properties would be based on a GObject property, but some wouldn't be, correct? > If there is enough interest, I will keep investigating. But > for now, helping with meson seems more urgent. Yes. /me warily eyes the monster lurking in the review queue... [...]