Rather than totally disable all Guest Addition features, you can just disable the time sync function.
You can turn the VirtualBox timesync off, but sometimes the VM then doesn't keep very good time and slips (it might only report 40 seconds of elapsed for every 60 seconds of elapsed real time, or it might be OK).
Or you can apply an offset to the time sync, so that the VM runs hours, days, years etc behind the host, but still maintains time sync.
Disable GA time-sync by editing the parameters passed to the VirtualBox Guest Additions Service (on Windows guests):
- Open Registry Editor (Start menu>Run...>Type 'regedit' into the 'Open:' field>Click the OK button)
WARNING: Incorrect editing of the registry can damage your system.
- Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VBoxService
- Double-click on 'ImagePath'
- Change the 'Value data:' field to:
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system32\VBoxService.exe --disable-timesync
- Click OK
- Either reboot the VM, or stop and then restart the 'VirtualBox Guest Additions Service'
To restart the 'VirtualBox Guest Additions Service':
- Right-click 'My Computer' on the desktop and select 'Manage'
- Expand 'Services and Applications' and select 'Services'
- Find service: 'VirtualBox Guest Additions Service' in the list
- Right-click>Properties
- Click 'Stop' button
- Click 'Start' button
After these steps, timesync will be disabled.
To reenable timesync, repeat the steps but remove the --disable-timesync parameter.
Keywords: time clock sync synchronisation synchronization
OR A time offset can be set using:
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VBoxManage modifyvm "My VM" --biossystemtimeoffset <msec>
... this should set the VM clock to be in sync with the host clock, but <msec> (milliseconds) offset. Negative numbers put the VM clock in the past, positive numbers put the VM into the future.