Red Hat Bugzilla – Bug 865315
RFE: use -rtc driftfix=slew
Last modified: 2013-07-03 22:52:27 EDT
Description of problem:
I'm not sure what the default downstream of driftfix is, but it should be slew to prevent Windows from BSOD.
RHEV/oVirt sets this option in the QEMU command line.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
This was included in Folsom:
Author: Daniel P. Berrange <email@example.com>
Date: Mon Jun 11 17:16:10 2012 +0100
Update default policies for KVM guest PIT & RTC timers
The default policies for the KVM guest PIT and RTC timers
are not very good at maintaining reliable time in guest
operating systems. In particular Windows 7 guests will
often crash with the default KVM timer policies, and old
Linux guests will have very bad time drift
Set the PIT such that missed ticks are injected at the
normal rate, ie they are delayed
Set the RTC such that missed ticks are injected at a
higher rate to "catch up"
This corresponds to the following libvirt XML
<timer name='pit' tickpolicy='delay'/>
<timer name='rtc' tickpolicy='catchup'/>
And the following KVM options
This should provide a default configuration that works
acceptably for most OS types. In the future this will
likely need to be made configurable per-guest OS type.
Fixes LP bug #1011848
Signed-off-by: Daniel P. Berrange <firstname.lastname@example.org>