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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A9F55D3CCAB for ; Fri, 16 Jan 2026 09:48:53 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vggKt-0008Nh-L7; Fri, 16 Jan 2026 04:41:43 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vggKq-0008NS-PY for qemu-devel@nongnu.org; Fri, 16 Jan 2026 04:41:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vggKo-00076P-NT for qemu-devel@nongnu.org; Fri, 16 Jan 2026 04:41:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1768556496; 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=8aFhZMp5E3IpPSWYxqARTYxghBCbE5ik3GYLDTYnjSQ=; b=XD9DS+15QuoagYHRoAm70dj1LTwg8QePTROw+4kUasaspMINHapLhWlYrZTDKFFzqncs+t NnJQDf+gnNf1MoOaHjjcFMFr7mgNnMcs61xWGpm8Pt6eJU88ElELzoUk2nrMEwg6FoRLfT 7Jz6movuwn7U/Owi0SlveuYhY0Z+hhs= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-502-NSkVkpZmM-2XMsbB0UgHpw-1; Fri, 16 Jan 2026 04:41:33 -0500 X-MC-Unique: NSkVkpZmM-2XMsbB0UgHpw-1 X-Mimecast-MFC-AGG-ID: NSkVkpZmM-2XMsbB0UgHpw_1768556491 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 621B61956096; Fri, 16 Jan 2026 09:41:31 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.32]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 748F618004D8; Fri, 16 Jan 2026 09:41:30 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0BB6A21E692D; Fri, 16 Jan 2026 10:41:28 +0100 (CET) From: Markus Armbruster To: Zhang Chen Cc: Lukas Straub , Peter Xu , qemu-devel@nongnu.org, Juraj Marcin , Fabiano Rosas , Daniel P . =?utf-8?Q?Berrang=C3=A9?= , Juan Quintela , "Dr. David Alan Gilbert" , zhanghailiang@xfusion.com, Li Zhijian , Jason Wang Subject: Re: [PATCH 1/3] migration/colo: Deprecate COLO migration framework In-Reply-To: (Zhang Chen's message of "Fri, 16 Jan 2026 16:22:19 +0800") References: <20260114195659.2543649-1-peterx@redhat.com> <20260114195659.2543649-2-peterx@redhat.com> <20260115224929.616aab85@penguin> <87ecnqt6nc.fsf@pond.sub.org> Date: Fri, 16 Jan 2026 10:41:28 +0100 Message-ID: <87ecnpyjw7.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Zhang Chen writes: > On Fri, Jan 16, 2026 at 2:26=E2=80=AFPM Markus Armbruster wrote: >> >> Lukas Straub writes: >> >> > On Wed, 14 Jan 2026 15:11:55 -0500 >> > Peter Xu wrote: >> > >> >> On Wed, Jan 14, 2026 at 02:56:57PM -0500, Peter Xu wrote: >> >> > COLO was broken for QEMU release 10.0/10.1 without anyone noticed. = One >> >> > reason might be that we don't have an unit test for COLO (which we >> >> > explicitly require now for any new migration feature). The other r= eason >> >> > should be that there are just no more active COLO users, at least b= ased on >> >> > the latest development of QEMU. >> >> > >> >> > I don't remember seeing anything really active in the past few year= s in >> >> > COLO development. >> >> > >> >> > Meanwhile, COLO migration framework maintainer (Hailiang Zhang)'s l= ast >> >> > email to qemu-devel is in Dec 2021 where the patch proposed an email >> >> > change (<20211214075424.6920-1-zhanghailiang@xfusion.com>). >> >> > >> >> > We've discussed this for a while, see latest discussions here (our = thoughts >> >> > of deprecating COLO framework might be earlier than that, but still= ): >> >> > >> >> > https://lore.kernel.org/r/aQu6bDAA7hnIPg-y@x1.local/ >> >> > https://lore.kernel.org/r/20251230-colo_unit_test_multifd-v1-0-f973= 4bc74c71@web.de >> >> > >> >> > Let's make it partly official and put COLO into deprecation list. = If >> >> > anyone cares about COLO and is deploying it, please send an email to >> >> > qemu-devel to discuss. >> >> > >> >> > Otherwise, let's try to save some energy for either maintainers or >> >> > developers who is looking after QEMU. Let's save the work if we don= 't even >> >> > know what the work is for. >> >> > >> >> > Cc: Luk=C3=A1=C5=A1 Doktor >> >> >> >> My apologize, I copied the wrong email. >> >> >> >> Cc: Lukas Straub >> > >> > Nack. >> > >> > This code has users, as explained in my other email: >> > https://lore.kernel.org/qemu-devel/20260115224516.7f0309ba@penguin/T/#= mc99839451d6841366619c4ec0d5af5264e2f6464 >> >> Code being useful is not enough. We must have people to maintain it >> adequately. This has not been the case for COLO in years. >> >> Deprecating a feature with intent to remove it is not a death sentence. >> It's a *suspended* death sentence: if somebody steps up to maintain it, >> we can revert the deprecation, or extend the grace period to give them a >> chance. >> >> I think we should deprecate COLO now to send a clear distress signal. >> The deprecation notice should explain it doesn't work, and will be >> removed unless people step up to fix it and to maintain it. This will >> ensure progress one way or the other. Doing nothing now virtually >> ensures we'll have the same discussion again later. >> >> "Broken for two releases without anyone noticing" and "maintainer absent >> for more than four years" doesn't exacltly inspire hope, though. We >> should seriously consider removing it right away. >> >> Lukas, can you give us hope? >> > > Hi Markus, > Maybe you missed something? > I think Lukas is ready to maintain this code in his previous emails. > https://lore.kernel.org/qemu-devel/20260115224516.7f0309ba@penguin/T/#mc9= 9839451d6841366619c4ec0d5af5264e2f6464 Patch to MAINTAINERS or it didn't happen ;)