From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54328) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V4Q2F-0000jV-HV for qemu-devel@nongnu.org; Wed, 31 Jul 2013 02:37:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V4Q2A-0000gG-Gf for qemu-devel@nongnu.org; Wed, 31 Jul 2013 02:37:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39374) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V4Q2A-0000gA-82 for qemu-devel@nongnu.org; Wed, 31 Jul 2013 02:37:18 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r6V6bHTb025739 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 31 Jul 2013 02:37:17 -0400 Message-ID: <51F8B09C.3010004@redhat.com> Date: Wed, 31 Jul 2013 08:37:16 +0200 From: Michal Novotny MIME-Version: 1.0 References: <7f847cb5fd7c350e1460df5772c5a0481bc77b3c.1375211373.git.minovotn@redhat.com> <51F81412.10809@redhat.com> In-Reply-To: <51F81412.10809@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3] vl.c: Output error on invalid machine type provided List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: qemu-devel@nongnu.org On 07/30/2013 09:29 PM, Eric Blake wrote: > On 07/30/2013 01:10 PM, Michal Novotny wrote: >> Output error message when user provides the invalid machine type >> on the command line. This also saves time to find what issue is >> when you upgrade from one version of qemu to another version that >> doesn't support required machine type any longer. > I know that has historically happened downstream (for example, Fedora 13 > made the mistake of creating a downstream-only fedora-13 machine type > that corresponded roughly to qemu 0.13, it took some further Fedora > patches to libvirt to modernize that name back to an upstream machine > type on an upgrade path before finally being able to drop the downstream > nonsense in Fedora 18 or so). But isn't upstream qemu supposed to be > guaranteeing command-line stability, in that a newer qemu will never > take away a machine type supported by an older qemu? > > But even if the upstream upgrade path never hits this code, your patch > will make it nicer if you _downgrade_ to a version of qemu (still with > this patch, of course) that lacks support for a newer machine. And the > fact that downstream will take advantage of this even if upstream never > causes the problem on upgrades still justifies using it. You are correct, Eric. I sent a patch v4 to output error message to stderr instead so I fixed the commit message. Thanks, Michal -- Michal Novotny , RHCE, Red Hat Virtualization | libvirt-php bindings | php-virt-control.org