On 26/10/2022 11:33, Scott Cheloha wrote:
There might be a second workaround. Kalabic mentions here in the
other thread about this problem:
https://marc.info/?l=openbsd-bugs&m=166664949825616&w=2
... that changing the ESXi option "Guest OS Version" from "FreeBSD
(32-bit)" to "FreeBSD (64-bit)" seemed to fix the problem on his
version of ESXi. Does that work for you? I don't know what the other
consequences of that configuration change are, but it might be worth a
try if you prefer to run 7.2-RELEASE or 7.2-STABLE instead of patching
-current.
Do you have VMware support? Is there any way for you to report this
problem to them? It's unlikely they explicitly support running an
OpenBSD guest, but it's plausible this issue could affect other
operating systems. I can't imagine OpenBSD is reading the ACPI PM
timer differently than Linux or FreeBSD.
Maybe related or not, but there's official paper from VMware that
describes several known timekeeping issues and how to correct or work
around them:
https://www.cse.psu.edu/~buu1/teaching/spring06/papers/vmware-timing.pdf
Also pardon my ignorance about TSC counters and related stuff, but just
looking at FreeBSD related code it seems to take into account the fact
it is running as a hypervisor guest (ESXi or Xen).
https://github.com/freebsd/freebsd-src/blob/main/sys/x86/x86/tsc.c
Is there a detail that makes a difference when different "Guest OS
Version" is used? Note that I have no idea what is happening there.
So, just like some AMD related improvements for TSC were introduced into
OpenBSD recently, maybe this issue can be properly solved only by doing
something similar for guests on hypervisor?
I have found that similar issues were reported for FreeBSD and other
virtual machines previously:
- "Time drift/system clock too fast on a PFSense VM":
https://forum.netgate.com/topic/108653/time-drift-system-clock-too-fast-on-a-pfsense-vm
- "Clock on ADC VPX hosted on VMware is running very fast causing
exchange issues":
https://support.citrix.com/article/CTX335923/clock-on-adc-vpx-hosted-on-vmware-is-running-very-fast-causing-exchange-issues
- ... and more can easily be googled.
