Guest Time drift: Difference between revisions

Revision as of 23:44, 16 October 2013

Some tips if you have time drifts (mainly for windows)

Using the Real-Time Clock with Windows Server 2003 and Windows XP guests

Windows uses the both the Real-Time Clock (RTC) and the Time Stamp Counter (TSC).

For Windows guests the RTC can be used instead of the TSC for all time sources, which resolves guest timing issues.

To enable the RTC for the PMTIMER clock source (usually uses the TSC), add the option /usepmtimer to the end of the boot line in boot.ini.

In your windows guest:

C:\Windows\system32>bcdedit /set {default} USEPLATFORMCLOCK on

@@ Line 11: / Line 11: @@
 Windows uses the both the Real-Time Clock (RTC) and the Time Stamp Counter (TSC).
-For Windows guests the Real-Time Clock can be used instead of the TSC for all time sources which resolves guest timing issues.
+For Windows guests the RTC can be used instead of the TSC for all time sources, which resolves guest timing issues.
-To enable the Real-Time Clock for the PMTIMER clock source (the PMTIMER usually uses the TSC), add the following option to the Windows boot settings.
+To enable the RTC for the PMTIMER clock source (usually uses the TSC), add the option '''/usepmtimer''' to the end of the boot line in '''boot.ini'''.
-Windows boot settings are stored in the boot.ini file.
-Add the following option to the end of the Windows boot line in the boot.ini file:
-/usepmtimer
 ==WIN VISTA - WIN7 - WIN2008==