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 312E3E91283 for ; Thu, 5 Feb 2026 07:08:39 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vntSw-0004nb-Hx; Thu, 05 Feb 2026 02:07:51 -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 1vntSu-0004nM-F3 for qemu-devel@nongnu.org; Thu, 05 Feb 2026 02:07:48 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vntSr-00022S-Ud for qemu-devel@nongnu.org; Thu, 05 Feb 2026 02:07:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770275263; 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=o0VPvmEwBad5lS36eO9V5wZj7P8JpKq8667gE1Y8/SM=; b=VPGulFl0c5QmEDV2OJ5n4otAS2OP5092Qp59GzJXNAA5X1hoaJzJMjr4q0fCUgmyMXKpxm XVGbdHJ1eYtWhDJ+znvF9vFbhY7/G3tM/N1YnCKgvhLr5Pn955U1Qbc8OO5xgvCMjFxymi APSMpJTEjGcBcAoPEZjqvCcSknEDKLA= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-265-d3igbw_eOta4E3oJPh3Vlg-1; Thu, 05 Feb 2026 02:07:40 -0500 X-MC-Unique: d3igbw_eOta4E3oJPh3Vlg-1 X-Mimecast-MFC-AGG-ID: d3igbw_eOta4E3oJPh3Vlg_1770275259 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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8007D18003FC; Thu, 5 Feb 2026 07:07:38 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.22]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BDE881800464; Thu, 5 Feb 2026 07:07:36 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 5444421E692D; Thu, 05 Feb 2026 08:07:34 +0100 (CET) From: Markus Armbruster To: Peter Xu Cc: Vladimir Sementsov-Ogievskiy , jasowang@redhat.com, mst@redhat.com, pbonzini@redhat.com, berrange@redhat.com, thuth@redhat.com, armbru@redhat.com, eblake@redhat.com, farosas@suse.de, 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 v10 3/8] qapi: add backend-transfer migration parameter In-Reply-To: (Peter Xu's message of "Wed, 4 Feb 2026 12:21:05 -0500") References: <20260201162001.296328-1-vsementsov@yandex-team.ru> <20260201162001.296328-4-vsementsov@yandex-team.ru> Date: Thu, 05 Feb 2026 08:07:34 +0100 Message-ID: <87ecmzu0qx.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 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; 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_H2=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 Peter Xu writes: > On Sun, Feb 01, 2026 at 07:19:55PM +0300, Vladimir Sementsov-Ogievskiy wrote: >> # @migrate-set-parameters: >> @@ -1004,6 +1005,13 @@ >> # is @cpr-exec. The first list element is the program's filename, >> # the remainder its arguments. (Since 10.2) >> # >> +# @backend-transfer: Enable backend-transfer feature for devices that >> +# supports it. In general that means that backend state and its >> +# file descriptors are passed to the destination in the migraton >> +# channel (which must be a UNIX socket). Individual devices >> +# declare the support for backend-transfer by per-device >> +# backend-transfer option. (Since 11.0) > > I still think it'll be nice to either have "local" in the name of parameter > or at least document it with crystal clear terms. > > I used to suggest fd-passing, but maybe you wanted to emphasize there's > more than fds to be migrated at least for tap? Then it can still be > "local-backend-transfer", because nobody stops a device to transfer backend > states in a remote migration either.. so "backend-transfer" seems to also > work for remote migrations, but it is not. > > Or at least mentioned explicitly in the comment, saying this is a local > migration / upgrade. Documenting the restriction is a must regardless of naming. The proposed text does document it, but only indirectly: "(which must be a UNIX socket)". Could be improved, I guess. Capturing the restriction in the name might help. But it also makes the name longer. Feels like a matter of taste to me. You guys decide :) > If you could at least update the doc on the locality attribute for the > migration (one way or another..), feel free to take: > > Acked-by: Peter Xu > > If you decide to rename, that's even better. > > Thanks,