" None of this makes much sense. It's certainly worth instrumenting " SETTIME.

I added a printk in do_dom0ops. I saw the same 70 minute jump ahead in the system clock in domain 0 when I shutdown domain 1. I did not get any new SETTIME printk from xm dmesg. The only settime calls occured when dom0 booted and ntp started.

The client domains do not have CONFIG_XEN_PRIVILEGED_GUEST set and nothing unusual is running on dom0. I start up xen0, then xenU, then kill xenU and the xen0 date immediately jumps.

" No -- SETTIME effectively sets the dom0 system time, that Xen " also exports to other domains.

So does that mean from the dom0 perspective that system time and hwclock time should always be identical?

What hwclock says on dom0 did not change. Just what date says changed.