[pve-devel] timedrift on win7/2008 with hpet timer

[Alexandre DERUMIER]

Hi,

users reports some time drifts problem with win7 and win2008 guests.
http://forum.proxmox.com/threads/8943-Time-running-fast-after-upgrading-to-PVE-2-final

from wikipedia:
http://en.wikipedia.org/wiki/High_Precision_Event_Timer

not able to use HPET: Windows XP sp2,[note 2] Windows Server 2003, and earlier Windows versions
 able to use HPET: Windows XP sp3,Windows 2008, Windows Vista, Windows 7

The problem seem to be that HPET timer doesn't have timedrift compensation in current kvm

I also check on the redhat side, they disable hpet by default (-no-hpet) since 2010
https://bugzilla.redhat.com/show_bug.cgi?id=595130


default redhat libvirt config for timers:


<clock mode="localtime">
	<timer name="rtc" tickpolicy="catchup" wallclock="guest" />
	<timer name="pit" tickpolicy="none" />
	<timer name="hpet" present="no" />
</clock>

give

   
   -clock base=localtime,clock=guest,driftfix=slew
   -no-kvm-pit-reinjection
   -no-hpet


maybe could it good to add  -no-kvm-pit-reinjection -no-hpet by default for win7,win2008 guests ?