On 19 June 2015 at 18:07, Anil Madhavapeddy <[email protected]> wrote: > On 19 Jun 2015, at 17:50, Justin Cormack <[email protected]> wrote: >> >> On 19 June 2015 at 17:42, Martin Lucina <[email protected]> wrote: >>> Also note that I have no idea what the stability of TSC is under KVM and >>> the current code makes no attempt to figure out if TSC is invariant, >>> constant, or anything else. So option 3) would also be a safe(r) bet in >>> that the PIT should "just work". >> >> KVM has a PV clock, see summary of how it works here >> https://rwmj.wordpress.com/tag/kvmclock/ >> >> Because clocks under virtualization are problematic, using this is >> probably the best solution longer term. > > On Xen HVM, you can still use the PV hypercall to map the shared_info > page and get the PV clock from there. Does all of that "just work" > from the NetBSD Xen PCI bridge device driver and Rump/Xen?
No one has looked at Xen/HVM yet as far as I know; upstream NetBSD does not support PVHVM yet which would be one approach. Now Amazon seem to be phasing out PV on favour of PV on HVM I guess this is getting more urgent. Justin
