From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MGASW-0005zX-As for qemu-devel@nongnu.org; Mon, 15 Jun 2009 07:34:40 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MGASQ-0005xx-Kj for qemu-devel@nongnu.org; Mon, 15 Jun 2009 07:34:38 -0400 Received: from [199.232.76.173] (port=47227 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MGASQ-0005xj-Fg for qemu-devel@nongnu.org; Mon, 15 Jun 2009 07:34:34 -0400 Received: from mx2.redhat.com ([66.187.237.31]:33323) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MGASQ-0001pe-0k for qemu-devel@nongnu.org; Mon, 15 Jun 2009 07:34:34 -0400 Message-ID: <4A36314A.8040206@redhat.com> Date: Mon, 15 Jun 2009 14:32:26 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: Configuration vs. compat hints [was Re: [Qemu-devel] [PATCHv3 03/13] qemu: add routines to manage PCI capabilities] References: <20090610145540.GI19375@poweredge.glommer> <20090610150129.GC28601@redhat.com> <200906101624.30659.paul@codesourcery.com> <20090610174301.GC7416@shareable.org> <20090610182227.GN28601@redhat.com> <20090610192702.GH7416@shareable.org> <1244796209.16425.20.camel@blaa> <4A326C7E.3020309@codemonkey.ws> <1244822007.30522.68.camel@blaa> <4A327E87.6080005@codemonkey.ws> <1244825333.26769.20.camel@blaa> <4A34ADA9.80709@redhat.com> <1245056955.6891.33.camel@blaa> In-Reply-To: <1245056955.6891.33.camel@blaa> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark McLoughlin Cc: Carsten Otte , kvm@vger.kernel.org, "Michael S. Tsirkin" , Glauber Costa , Rusty Russell , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Blue Swirl , Christian Borntraeger , Paul Brook On 06/15/2009 12:09 PM, Mark McLoughlin wrote: >>>> I think the point is that you don't need version numbers if you have a >>>> proper device tree. >>>> >>>> >>> How do you add a new attribute to the device tree and, when a supplied >>> device tree lacking said attribute, distinguish between a device tree >>> from an old version of qemu (i.e. use the old default) and a partial >>> device tree from the VM manager (i.e. use the new default) ? >>> >>> >> -baseline 0.10 >> > > That's a version number :-) > > (I was responding to Anthony's "you don't need a version number") > If you want to prevent incompatibilities, you need to make everything new (potentially including bugfixes) non-default. Eventually the default configuration becomes increasingly unusable and you need a new baseline. You must still be able to fall back to the old baseline for older guests. I don't think games with configuration files can hide that. -- error compiling committee.c: too many arguments to function