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 85161EB1070 for ; Tue, 10 Mar 2026 15:23:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vzyvF-0007nv-79; Tue, 10 Mar 2026 11:23:01 -0400 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 1vzyvD-0007nl-QG for qemu-devel@nongnu.org; Tue, 10 Mar 2026 11:22:59 -0400 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 1vzyvA-0002f7-VF for qemu-devel@nongnu.org; Tue, 10 Mar 2026 11:22:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773156175; 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: in-reply-to:in-reply-to:references:references; bh=3Fzvf3v7hPgWIc8VdligtBDlOPc2L91UogibbjStJp0=; b=QBTFNsywBIhYNS0XLCErUQx2Llkfc+913MIKrxzVTRwCzXN6oHs2ZnP2NiznZ28P8uRya0 A/+vqC014WoWW1N7QpFtCQ9OdRwMQJ9SWSrTv1hON6hh0fYumsBF8d7VQk2HGIPXRSEhzc dpX4fDU9PI8xdxjiKjVr2ySLR5RjI/0= 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-402-tppurs3JMD6bZb8d1E07Og-1; Tue, 10 Mar 2026 11:22:52 -0400 X-MC-Unique: tppurs3JMD6bZb8d1E07Og-1 X-Mimecast-MFC-AGG-ID: tppurs3JMD6bZb8d1E07Og_1773156170 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 6210C1956068; Tue, 10 Mar 2026 15:22:49 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.12]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 05952180035F; Tue, 10 Mar 2026 15:22:48 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8BD8421E681B; Tue, 10 Mar 2026 16:22:45 +0100 (CET) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: jasowang@redhat.com, mst@redhat.com, thuth@redhat.com, eblake@redhat.com, farosas@suse.de, peterx@redhat.com, zhao1.liu@intel.com, wangyanan55@huawei.com, philmd@linaro.org, marcel.apfelbaum@gmail.com, eduardo@habkost.net, davydov-max@yandex-team.ru, qemu-devel@nongnu.org, yc-core@yandex-team.ru, leiyang@redhat.com, raphael.s.norwitz@gmail.com, bchaney@akamai.com Subject: Re: [PATCH v12 3/8] qapi: add local migration parameter In-Reply-To: (Vladimir Sementsov-Ogievskiy's message of "Tue, 10 Mar 2026 18:06:59 +0300") References: <20260306213235.216863-1-vsementsov@yandex-team.ru> <20260306213235.216863-4-vsementsov@yandex-team.ru> <87cy1biyeq.fsf@pond.sub.org> Date: Tue, 10 Mar 2026 16:22:45 +0100 Message-ID: <87wlzjg14q.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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: -3 X-Spam_score: -0.4 X-Spam_bar: / X-Spam_report: (-0.4 / 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.819, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.903, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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 Vladimir Sementsov-Ogievskiy writes: > On 10.03.26 16:53, Markus Armbruster wrote: >> Vladimir Sementsov-Ogievskiy writes: >> >>> We are going to implement local-migration feature: some devices will be >>> able to transfer open file descriptors through migration stream (which >>> must UNIX domain socket for that purpose). This allows to transfer the >>> whole backend state without reconnecting and restarting the backend >>> service. For example, virtio-net will migrate its attached TAP netdev, >>> together with its connected file descriptors. >>> >>> In this commit we introduce a migration parameter, which enables >>> the feature for supporting devices (no one at the moment). >> >> for devices that support it (none at the moment). >> >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> Reviewed-by: Peter Xu >> >> [...] >> >>> diff --git a/qapi/migration.json b/qapi/migration.json >>> index f925e5541bf..2c8d85f5834 100644 >>> --- a/qapi/migration.json >>> +++ b/qapi/migration.json >>> @@ -828,7 +828,8 @@ >>> 'mode', >>> 'zero-page-detection', >>> 'direct-io', >>> - 'cpr-exec-command'] } >>> + 'cpr-exec-command', >>> + 'local'] } >>> >>> ## >>> # @migrate-set-parameters: >>> @@ -1004,6 +1005,15 @@ >>> # is @cpr-exec. The first list element is the program's filename, >>> # the remainder its arguments. (Since 10.2) >>> # >>> +# @local: Enable local migration feature for devices that support >>> +# it. The feature is for local migration only and rely on the >>> +# channel support for passing file descriptors (it must be a UNIX >>> +# socket). In general that means that backend state and its file >>> +# descriptors are passed to the destination in the migration >>> +# channel. In general devices may have an option which in >>> +# conjunction with @local set to true enables the local-migration >>> +# feature for that device. (Since 11.0) >> >> This needs polish. Let me try. >> >> # @local: Enable local migration for devices that support it. Backend >> # state and its file descriptors are then passed to the >> # destination in the migration channel. The migration channel >> # must be a Unix domain socket. Also needs to be enabled per >> # device by setting device property "local" to true. > > As discussed in v11, we don't want to require neither concrete property name > nor even the existence of such property, that why it was worded "may have an option". > > https://lore.kernel.org/qemu-devel/aZyS4UizvDq1Wnpq@x1.local/ Scratch "by setting ..." then, and maybe replace "also" by "usually". [...]