From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38471) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1daHMU-00081e-Di for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:08:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1daHMQ-0003o2-Dx for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:08:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47158) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1daHMQ-0003nX-4y for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:08:02 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 29C49356F3 for ; Wed, 26 Jul 2017 08:08:01 +0000 (UTC) Date: Wed, 26 Jul 2017 09:07:54 +0100 From: "Daniel P. Berrange" Message-ID: <20170726080754.GB28914@redhat.com> Reply-To: "Daniel P. Berrange" References: <20170725141041.1195-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] qemu-options: document existance of versioned machine types List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow Cc: qemu-devel@nongnu.org, Paolo Bonzini On Tue, Jul 25, 2017 at 01:46:23PM -0400, John Snow wrote: > > > On 07/25/2017 10:10 AM, Daniel P. Berrange wrote: > > The -machine docs did not explain what the versioned machine > > types are for, nor that they'll be maintained across > > releases. > > > > Signed-off-by: Daniel P. Berrange > > --- > > qemu-options.hx | 15 ++++++++++++++- > > 1 file changed, 14 insertions(+), 1 deletion(-) > > > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 746b5fa75d..9f6e2adfff 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -49,7 +49,20 @@ STEXI > > @item -machine [type=]@var{name}[,prop=@var{value}[,...]] > > @findex -machine > > Select the emulated machine by @var{name}. Use @code{-machine help} to list > > -available machines. Supported machine properties are: > > +available machines. > > + > > +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 guests from QEMU version 2.8.0, to QEMU > > +version 2.9.0, the 2.9.0 version must support the ``pc-i440fx-2.8'' > > +and ``pc-q35-2.8'' machines too. 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. > > + > > +Supported machine properties are: > > @table @option > > @item accel=@var{accels1}[:@var{accels2}[:...]] > > This is used to enable an accelerator. Depending on the target architecture, > > > > Seems like an improvement to me, but do we have any formal policy on how > long we support said machine types? The new wording prompts that question. I wasn't going to mention that in this patch, to avoid delay on getting it merged. I was going to send a further patch that makes it explicit that we will never delete machine types for as long as any active QEMU contributor has need for them in downstream version they maintain > Reviewed-by: John Snow Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|