From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:32870)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <lcapitulino@redhat.com>) id 1SxMCA-0006H8-8D
	for qemu-devel@nongnu.org; Fri, 03 Aug 2012 14:01:55 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <lcapitulino@redhat.com>) id 1SxMC9-0001kB-2X
	for qemu-devel@nongnu.org; Fri, 03 Aug 2012 14:01:54 -0400
Received: from mx1.redhat.com ([209.132.183.28]:26849)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <lcapitulino@redhat.com>) id 1SxMC8-0001k2-PP
	for qemu-devel@nongnu.org; Fri, 03 Aug 2012 14:01:52 -0400
Date: Fri, 3 Aug 2012 15:02:25 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
Message-ID: <20120803150225.6a645209@doriath.home>
In-Reply-To: <501C10CD.10402@redhat.com>
References: <1343869374-23417-1-git-send-email-lcapitulino@redhat.com>
	<1343869374-23417-31-git-send-email-lcapitulino@redhat.com>
	<20120803174433.GB16157@illuin> <501C10CD.10402@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 30/34] qemu-ga: switch to the new error
 format on the wire
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Eric Blake <eblake@redhat.com>
Cc: kwolf@redhat.com, aliguori@us.ibm.com, qemu-devel@nongnu.org, armbru@redhat.com, Michael Roth <mdroth@linux.vnet.ibm.com>, pbonzini@redhat.com

On Fri, 03 Aug 2012 11:56:29 -0600
Eric Blake <eblake@redhat.com> wrote:

> On 08/03/2012 11:44 AM, Michael Roth wrote:
> > On Wed, Aug 01, 2012 at 10:02:50PM -0300, Luiz Capitulino wrote:
> >> IMPORTANT: this BREAKS qemu-ga compatibility for the error response.
> >>
> >> Instead of returning something like:
> >>
> >> { "error": { "class": "InvalidParameterValue",
> >>              "data": {"name": "mode", "expected": "halt|powerdown|reboot" } } }
> >>
> >> qemu-ga now returns:
> >>
> >>  { "error": { "class": "GenericError",
> >>               "desc": "Parameter 'mode' expects halt|powerdown|reboot" } }
> > 
> 
> >>
> >> Notice that this is also a bug fix, as qemu-ga wasn't returning the
> >> human message.
> >>
> >> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> > 
> > So, if the libvirt folks are okay with it:
> 
> The only use libvirt made of existing qemu-ga errors was to stringify
> them in order to pass on an error message to the user when a command
> failed.  Existing libvirt attempts to look up the 'desc' field, and when
> it is lacking, then attempts to stringify the 'class' field based on a
> finite list of known classes.  Qemu is now shrinking the list of known
> classes but providing a 'desc' field, so the error message quality in
> libvirt will actually improve.  After reading libvirt's
> src/qemu/qemu_agent.c, I don't see any problem with this patch from
> libvirt's point of view.

Yeah, I actually have a request from Michal to do just that (add 'desc'
to qemu-ga's errors).

> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
>