On Mon, Sep 25, 2023 at 04:26:59PM +0200, Alice Frosi wrote: > Hi Rich, > > On Mon, Sep 25, 2023 at 4:10 PM Richard W.M. Jones <rjo...@redhat.com> wrote: > > [Alice: See patch 2] > > > I'm not 100% sure about the source of this work. However, we had in > KubeVirt people interested in using localtime with Windows [1]. Yes, > I see that you pointed to that PR in patch 2. The problem with that > PR is the migration. What happens if we migrate the VM to a host > that is in another timezone? Is it going to break the application > running inside the VM?
Does every Windows VM running in Kubevirt have its registry adjusted so it expects the BIOS to be set to UTC? (ie: https://wiki.archlinux.org/title/System_time#UTC_in_Microsoft_Windows). This is a non-standard setting, but I can't understand how Windows VMs would have correct clocks if this were not the case. BTW you could find out by running: $ virt-win-reg window.img 'HKLM\SYSTEM' on some Kubevirt Windows VMs, and looking for: [\ControlSet001\Control\TimeZoneInformation] in the output. See if there is a key called "RealTimeIsUniversal" and what it is set to. If it is the case that this is always set for existing Kubevirt guests, then virt-v2v would have to be changed so it also sets this registry entry when the output is Kubevirt. I agree that migration across timezones is highly problematic for the BIOS = localtime situation. I don't see any solution for that except disallowing it. > IMO, that was the major blocker of that PR. I initially suggested that we > either avoid migration as a first step or try to migrate only on nodes at the > same timezone, > Do you know if anyone has experience on this particular problem? I guess RHV must have encountered this before, but I don't know any specifics. Thanks, Rich. > [1] https://github.com/kubevirt/kubevirt/pull/9587 > > Many thanks, > Alice -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs
