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

[Eric Blake]

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 <address@hidden>
>>
>> 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.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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