libvirt users - Feb 2018 - Re: How to use rtc_timeoffset (XL toolkit option) in Libvirt and Xen/libxl hypervisor?

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@hw12xen ~]# cat goillltawdlssq.xl.cfg | grep offset
rtc_timeoffset = "7200"   # +2 hours to UTC time (or +/-3600=+/-1 hour
to
UTC time)
[root@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@hw12xen ~]# cat goillltawdlssq.var.xml | grep offset
  <clock offset='variable' adjustment='7200' />
[root@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   ?

Thanks in advance.

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@hw12xen ~]# cat goillltawdlssq.xl.cfg | grep offset
> rtc_timeoffset = "7200"   # +2 hours to UTC time (or +/-3600=+/-1
hour to UTC time)
> [root@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@hw12xen ~]# cat goillltawdlssq.var.xml | grep offset
>    <clock offset='variable' adjustment='7200' />
> [root@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

Jim,

Thanks a lot for your confirmation.
Could you also please explain if the issue can be ever fixed, if it's
possible to make some patch to fix it?
Is it libvirt-specific bug or Libvirt development team rely on some other
developers of libxl code...etc?
I'm asking because XL tools works fine and I wonder if XL uses the same
libxl libraries , doesn't it?
Lastly is the issue is going be fixed in near time? Can you answer my
questions and ask for some patch for
enhancement request or I should better send a separate email to development
team ("libvir-list@redhat.com
<https://www.redhat.com/mailman/listinfo/libvir-list>") ?
Thanks a lot in advance for your answers...


On Fri, Feb 16, 2018 at 8:37 PM, Jim Fehlig <jfehlig@suse.com> wrote:
> 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@hw12xen ~]# cat goillltawdlssq.xl.cfg | grep offset
>> rtc_timeoffset = "7200"   # +2 hours to UTC time (or
+/-3600=+/-1 hour to
>> UTC time)
>> [root@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@hw12xen ~]# cat goillltawdlssq.var.xml | grep offset
>>    <clock offset='variable' adjustment='7200' />
>> [root@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
>
>