On Thu, Jan 02, 2025 at 05:11:01PM +0100, Peter Hilber wrote:

Would it be more acceptable to just announce leap seconds, but not
whether to smear?

Up until now, leap second announcements were handled in user space,
and the kernel played no role.

I do not understand. Is the point that guests should decide through
another channel about leap second smearing?

Yes, that would make more sense to me.

I hope there will be some feedback from third parties (at least related
to virtualization).

+1

I'm no VM expert, but I'd like to avoid tacking things onto the kernel
PTP layer, unless there is a really strong justification.

For sure. But the aim of this proposal is to have an interoperable time
synchronization solution for VMs through a Virtio device. So the idea is
to include metrics, if a consensus on their usefulness can be reached.
AFAIU it is difficult to bypass the kernel for Virtio devices.

Providing clock metrics only makes sense when there is some choice to
be made based on those metrics.  If the "limited" VM guests don't even
have networking, then they have no choice but to accept the time from
the VM host, right?  In which case, the metrics do not provide any
benefit to the guest.

Or what am I missing?

Thanks,
Richard