From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36267) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dZdjw-0007ld-V4 for qemu-devel@nongnu.org; Mon, 24 Jul 2017 09:49:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dZdju-0004AR-7Q for qemu-devel@nongnu.org; Mon, 24 Jul 2017 09:49:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54402) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dZdju-00047u-0j for qemu-devel@nongnu.org; Mon, 24 Jul 2017 09:49:38 -0400 References: <20170719100802.14094-1-berrange@redhat.com> <20170719100802.14094-2-berrange@redhat.com> From: Paolo Bonzini Message-ID: Date: Mon, 24 Jul 2017 15:49:29 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 1/2 (for 2.10)] docs: document support lifetime for features List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth , "Daniel P. Berrange" , qemu-devel@nongnu.org Cc: Peter Maydell , Stefan Hajnoczi , Markus Armbruster , Eduardo Habkost On 19/07/2017 13:56, Thomas Huth wrote: > +@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. I think there's still no consensus on this. The first two paragraphs should be added to the documentation for -machine in qemu-options.hx, since "-machine [type=]foo" is currently not documented at all. Paolo