From nobody Sat Feb 7 15:29:29 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1500028118184422.92236700024284; Fri, 14 Jul 2017 03:28:38 -0700 (PDT) Received: from localhost ([::1]:36792 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dVxpt-0000Jc-1Y for importer@patchew.org; Fri, 14 Jul 2017 06:28:37 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44230) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dVxdk-0005Xf-0O for qemu-devel@nongnu.org; Fri, 14 Jul 2017 06:16:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dVxdi-0007J1-St for qemu-devel@nongnu.org; Fri, 14 Jul 2017 06:16:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46010) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dVxdi-0007Ik-JM for qemu-devel@nongnu.org; Fri, 14 Jul 2017 06:16:02 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 93C8183F43; Fri, 14 Jul 2017 10:16:01 +0000 (UTC) Received: from t460.redhat.com (ovpn-117-13.ams2.redhat.com [10.36.117.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id 93F0170BA2; Fri, 14 Jul 2017 10:15:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 93C8183F43 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=berrange@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 93C8183F43 From: "Daniel P. Berrange" To: qemu-devel@nongnu.org Date: Fri, 14 Jul 2017 11:15:48 +0100 Message-Id: <20170714101549.28665-2-berrange@redhat.com> In-Reply-To: <20170714101549.28665-1-berrange@redhat.com> References: <20170714101549.28665-1-berrange@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 14 Jul 2017 10:16:01 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v4 1/2] docs: document support lifetime for features X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Eduardo Habkost , Markus Armbruster , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" There is currently no explicit guidance on the duration of support for features such as versioned machine types, which have a finite useful lifespan. Thus apps / users cannot predict how much time they might be able to use a feature for, before it is removed (if ever). This adds a new appendix that lists items which have finite lifecycles, such as machine types. For items which are generally expected to be supported indefinitely, it sets out the policy around deprecation and removal, should it be needed. Signed-off-by: Daniel P. Berrange --- qemu-doc.texi | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/qemu-doc.texi b/qemu-doc.texi index 48af5155c7..f067015d4b 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -38,6 +38,7 @@ * QEMU Guest Agent:: * QEMU User space emulator:: * Implementation notes:: +* Support lifetime:: * License:: * Index:: @end menu @@ -3128,6 +3129,42 @@ Run the emulation in single step mode. =20 @include qemu-tech.texi =20 +@node Support lifetime +@appendix Support lifetime + +In general features are intended to be supported indefinitely once +introduced into QEMU. + +In the event that a feature needs to be removed, it will be listed +in the ``Deprecated features'' appendix of this document. The feature +will remain functional for 2 major releases prior to actual removal. + +Deprecated features may also generate warnings on the console when +QEMU starts up, or if activated via a monitor command, however, +this is not a mandatory requirement. + +Certain features have an inherently finite lifetime, and thus +will be removed on a fixed schedule, without following the normal +deprecation process. Such features are listed in the sections +that follow. + +@node Machine types +@section Machine types + +For architectures which aim to support live migration compatibility +across releases, each release will introduce a new versioned machine +type. For example, the 2.8.0 release introduced machine types +``pc-i440fx-2.8'' and ``pc-q35-2.8'' for the x86_64/i686 architectures. + +To allow live migration of a guest running on a 2.8.0 release to a +2.9.0, the QEMU 2.9.0 version must support the ``pc-i440fx-2.8'' and +``pc-q35-2.8''. To allow users live migrating VMs to skip multiple +intermediate releases when upgrading, new releases of QEMU will +support machine types from many previous versions. + +The supported lifetime for versioned machine types is 12 releases, +which is equivalent to 4 years worth of previous QEMU releases. + @node License @appendix License =20 --=20 2.13.0