Windows-10 – Fixing Wrong Time Display When Dual-Booting with Ubuntu

I had a similar issue with ArchLinux guest in VirtualBox host. When I use TIMEZONE="Africa/Johannesburg" or TIMEZONE="Asia/Bahrain" in my rc.conf file, the output of date is correct but when I use TIMEZONE="/Etc/GMT+2" or "/Etc/GMT+3" (corresponding to aforementioned timezones) then the VBoxService sets time 6 hours to early.

My hardware clock time always remains correct (sudo hwclock --show) and setting system time from hardware clock (sudo hwclock --hctosys) sets system time correctly until VBoxService runs timesync again and output of date is 6 hours too early.

To summarize; using timezones from /usr/share/zoneinfo// seems to work but other zoneinfos might not work, I don't know why this is.

Yep, I had success. Don't forget disabling the "internet update" for the time!

I used the way described in the ArchWiki using a QWORD on a 64bit Win10. The NTP is done on Arch and not on Windows, but the latter isnt getting booted so often anyway.

Here's the .reg file:

RealTimeIsUniversal.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
     "RealTimeIsUniversal"=hex(b):01,00,00,00,00,00,00,00

From ArchWiki: UTC in Windows

Using regedit, add a DWORD value with hexadecimal value 1 to the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal

Alternatively, create a *.reg file (on the desktop) with the following content and double-click it to import it into registry:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
 "RealTimeIsUniversal"=dword:00000001

If the above appears to have no affect, and a 64-bit variant of Windows is being used, using a QWORD value instead of a DWORD value may resolve the issue.