RealTimeIsUniversal - Windows VM - PV driver does not work

[jiri.hadamek]

We installed new VM (Windows 11 - 24H2) in XCP-ng (latest-version, from source).
Everything works fine, XEN tools work fine

Management agent 9.4.1-160 detected and works

We set-up in windows registry QWORD value HKLM\CurrentControlSet\CurrentControl\TimeZoeInformation\RealTimeIsUniversal=1
(We need this settings for many computers/VM with dual boot)

1. The VM cannot boot with using PV drivers - it use QEMU drivers.

2, in XOA the VM reported "management agent NOT installed" (In windows is reported as installed)

• XOA is unable report memory usage

If we tried to remove (manualy, by GPO or by script) this registry entry, VM is unable to boot (error: unaccesible boot device) or crashed (rarely).

I think it is bug in management agent/PV drivers for Windows.
Have you any solution for using PV drivers in Windows with setting BIOS/UEFI using real time clock as UTC?

[olivierlambert]

Hi,

Question for @dinhngtu

[dinhngtu]

@jiri.hadamek The drivers don't like that value being a REG_QWORD. Try using REG_DWORD instead.

[jiri.hadamek]

@dinhngtu "The drivers don't like that value being a REG_QWORD" - if you mean by that: "The PV driver doesn´t work correctly with qword value" then I will try set it to REG_DWORD even every documentation on Internet and in Microsoft demand QWORD.

Then I will put result here.

[jiri.hadamek]

With DWORD value the PV drivers work.
But the PV driver´s instability with QWORD value is worth to "be corrected". (by my opinion)

Solved.

[dinhngtu]

@jiri.hadamek Yes, it's a driver bug. I'll plan for a fix.

[dinhngtu]

Fix committed upstream.