Difference between revisions of "Guest Time drift"

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Windows uses the both the Real-Time Clock (RTC) and the Time Stamp Counter (TSC).  
 
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==
 
==WIN VISTA - WIN7 - WIN2008==

Revision as of 01:44, 17 October 2013

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

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/chap-Virtualization_Host_Configuration_and_Guest_Installation_Guide-KVM_guest_timing_management.html


WIN XP - WIN2003

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.

WIN VISTA - WIN7 - WIN2008

In your windows guest:

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