[libvirt-users] How to use rtc_timeoffset (XL toolkit option) in Libvirt and Xen/libxl hypervisor?

[Jim Fehlig]

On 02/16/2018 08:37 AM, Volo M. wrote:
> Hello techs,
> 
> We used XL toolkit for Xen hypervisor for starting Windows hvm VMs and the 
> option rtc_timeoffset worked perfectly with XL. It helped us to set correct 
> Timezone time/offset for Windows HVM VMs from inside virtual_machine xen config.
> 
> For example:
> Below option WORKS perfectly with XL toolkit.
> [root at hw12xen ~]# cat goillltawdlssq.xl.cfg | grep offset
> rtc_timeoffset = "7200"   # +2 hours to UTC time (or +/-3600=+/-1 hour to UTC time)
> [root at hw12xen ~]#
> 
> Now we try to migrate all the Windows hvm VMs to using Libvirt and Xen 4.6.6 (or 
> 4.4).
> But as we see it's impossible to make VMs using correct time/offset set in XML 
> config like below:
> 
> below Libvirt option DOESN'T WORK as we expect...
> [root at hw12xen ~]# cat goillltawdlssq.var.xml | grep offset
>    <clock offset='variable' adjustment='7200' />
> [root at hw12xen ~]#
> 
> Can you please explain if there's something we're doing wrong way or it's just a 
> bug like described here:
> https://bugzilla.redhat.com/show_bug.cgi?id=1212191   ?

No, you're not doing anything wrong. And yes, you've hit that bug, although I'd 
prefer to call it an enhancement request. Xen's rtc_timeoffset setting is 
currently not supported by the libvirt libxl driver.

Regards,
Jim