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Wed, 14 Jan 2026 12:12:05 -0800 (PST) X-Received: by 2002:a05:6102:304b:b0:5ef:a24a:50b5 with SMTP id ada2fe7eead31-5f19253ba4amr360148137.18.1768421524445; Wed, 14 Jan 2026 12:12:04 -0800 (PST) Received: from x1.local ([142.188.210.156]) by smtp.gmail.com with ESMTPSA id a1e0cc1a2514c-944122d3040sm23063638241.4.2026.01.14.12.11.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 12:12:03 -0800 (PST) Date: Wed, 14 Jan 2026 15:11:55 -0500 From: Peter Xu To: qemu-devel@nongnu.org Cc: Juraj Marcin , Fabiano Rosas , Markus Armbruster , Daniel P =?utf-8?B?LiBCZXJyYW5nw6k=?= , =?utf-8?B?THVrw6HFoQ==?= Doktor , Juan Quintela , "Dr. David Alan Gilbert" , Zhang Chen , zhanghailiang@xfusion.com, Li Zhijian , Jason Wang , Lukas Straub Subject: Re: [PATCH 1/3] migration/colo: Deprecate COLO migration framework Message-ID: References: <20260114195659.2543649-1-peterx@redhat.com> <20260114195659.2543649-2-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260114195659.2543649-2-peterx@redhat.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@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 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 reason > should be that there are just no more active COLO users, at least based on > the latest development of QEMU. > > I don't remember seeing anything really active in the past few years in > COLO development. > > Meanwhile, COLO migration framework maintainer (Hailiang Zhang)'s last > 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-f9734bc74c71@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: Lukáš Doktor My apologize, I copied the wrong email. Cc: Lukas Straub > Cc: Juan Quintela > Cc: Dr. David Alan Gilbert > Cc: Zhang Chen > Cc: zhanghailiang@xfusion.com > Cc: Li Zhijian > Cc: Jason Wang > Signed-off-by: Peter Xu > --- > docs/about/deprecated.rst | 6 ++++++ > qapi/migration.json | 5 ++--- > migration/options.c | 4 ++++ > 3 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > index 7abb3dab59..b499b2acb0 100644 > --- a/docs/about/deprecated.rst > +++ b/docs/about/deprecated.rst > @@ -580,3 +580,9 @@ command documentation for details on the ``fdset`` usage. > > The ``zero-blocks`` capability was part of the block migration which > doesn't exist anymore since it was removed in QEMU v9.1. > + > +COLO migration framework (since 11.0) > +''''''''''''''''''''''''''''''''''''' > + > +To be removed with no replacement, as the COLO migration framework doesn't > +seem to have any active user for a while. > diff --git a/qapi/migration.json b/qapi/migration.json > index 201dedd982..3c868efe38 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -531,8 +531,7 @@ > # > # @unstable: Members @x-colo and @x-ignore-shared are experimental. > # > -# @deprecated: Member @zero-blocks is deprecated as being part of > -# block migration which was already removed. > +# @deprecated: Member @zero-blocks and @x-colo are deprecated. > # > # Since: 1.2 > ## > @@ -540,7 +539,7 @@ > 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', > { 'name': 'zero-blocks', 'features': [ 'deprecated' ] }, > 'events', 'postcopy-ram', > - { 'name': 'x-colo', 'features': [ 'unstable' ] }, > + { 'name': 'x-colo', 'features': [ 'unstable', 'deprecated' ] }, > 'release-ram', > 'return-path', 'pause-before-switchover', 'multifd', > 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate', > diff --git a/migration/options.c b/migration/options.c > index 9a5a39c886..318850ba94 100644 > --- a/migration/options.c > +++ b/migration/options.c > @@ -580,6 +580,10 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp) > warn_report("zero-blocks capability is deprecated"); > } > > + if (new_caps[MIGRATION_CAPABILITY_X_COLO]) { > + warn_report("COLO migration framework is deprecated"); > + } > + > #ifndef CONFIG_REPLICATION > if (new_caps[MIGRATION_CAPABILITY_X_COLO]) { > error_setg(errp, "QEMU compiled without replication module" > -- > 2.50.1 > -- Peter Xu