Re: [Qemu-devel] [PULL 8/8] qga: Add `guest-get-timezone` command

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Apr 26, 2017 at 08:08:25AM -0500, Eric Blake wrote:
> On 04/26/2017 06:02 AM, Daniel P. Berrange wrote:
> > On Tue, Apr 25, 2017 at 06:04:41PM -0500, Michael Roth wrote:
> >> From: Vinzenz Feenstra <vfeenstr@redhat.com>
> >>
> >> Adds a new command `guest-get-timezone` reporting the currently
> >> configured timezone on the system. The information on what timezone is
> >> currently is configured is useful in case of Windows VMs where the
> >> offset of the hardware clock is required to have the same offset. This
> >> can be used for management systems like `oVirt` to detect the timezone
> >> difference and warn administrators of the misconfiguration.
> > 
> >> +GuestTimezone *qmp_guest_get_timezone(Error **errp)
> >> +{
> > 
> >> +    name = g_time_zone_get_abbreviation(tz, intv);
> > 
> > [snip]
> > 
> >> +##
> >> +# @GuestTimezone:
> >> +#
> >> +# @zone:    Timezone name
> > 
> > This isn't clearly documented in glib, but it looks like the time zone
> > names are *different* when glib is run on POSIX vs Win32 platforms.
> > 
> > Do we really want to expose something in QAPI that is going to have
> > different semantics depending on the guest OS the agent runs in ?
> > 
> 
> Maybe it's just a matter of proper documentation.  The 'offset' field is
> the important one, with unambiguous machine-parseable semantics; the
> 'zone' field is an optional, informative, human-readable format
> according to the guest OS's whims, and should not be relied on for
> scripting purposes.

Yeah, if it is only intended for informative purposes this should be
explicitly documented that it is not standardized across guests.

Regards,
Daniel
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