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Date: Wed, 18 Nov 2009 16:10:39 -0200
From: Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 10/10] monitor: do_info_balloon(): use QError
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To: Anthony Liguori <aliguori@linux.vnet.ibm.com>
Cc: kraxel@redhat.com, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

On Wed, 18 Nov 2009 09:58:30 -0600
Anthony Liguori <aliguori@linux.vnet.ibm.com> wrote:

> Markus Armbruster wrote:
> > Luiz Capitulino <lcapitulino@redhat.com> writes:
> >
> >   
> >> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> >> ---
> >>  monitor.c |    7 ++++---
> >>  1 files changed, 4 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/monitor.c b/monitor.c
> >> index 74abef9..e42434f 100644
> >> --- a/monitor.c
> >> +++ b/monitor.c
> >> @@ -1722,10 +1722,11 @@ static void do_info_balloon(Monitor *mon, QObject **ret_data)
> >>  
> >>      actual = qemu_balloon_status();
> >>      if (kvm_enabled() && !kvm_has_sync_mmu())
> >> -        monitor_printf(mon, "Using KVM without synchronous MMU, "
> >> -                       "ballooning disabled\n");
> >> +        qemu_error_new(QERR_SERVICE_UNAVAILABLE,
> >> +                      "Using KVM without synchronous MMU, ballooning disabled");
> >>      else if (actual == 0)
> >> -        monitor_printf(mon, "Ballooning not activated in VM\n");
> >> +        qemu_error_new(QERR_SERVICE_UNAVAILABLE,
> >> +                       "Ballooning not activated in VM");
> >>      else
> >>          *ret_data = QOBJECT(qint_from_int((int)(actual >> 20)));
> >>  }
> >>     
> >
> > In PATCH 7/10:
> >
> > +#define QERR_SERVICE_UNAVAILABLE \
> > +        "{ 'class': 'ServiceUnavailable', 'data': { 'reason': %s } }"
> > +
> >
> > and
> >
> > +    {
> > +        .error_fmt   = QERR_SERVICE_UNAVAILABLE,
> > +        .desc        = "%(reason)",
> > +    },
> >
> > How to do a ServiceUnavailable error with a description that is not a
> > compile time literal?  Add another macro and error table entry for that?
> >   
> 
> An error that just contains reason is a good indication that the error 
> is not the right level of abstraction.
> 
> There are two error conditions here.  One is that kvm is in use, but 
> it's missing a capability and therefore we have to disable a feature.   
> The second error is that the guest did not activate a device.

 Thanks for the detailed explanation, I've included the new errors.