Pkg xen devel - Aug 2011 - Bug#638837: independent_wallclock sysctl has gone away?

Package: xen
Severity: important
Version: 4.0.1-1

The Xen documentation and Xen Debian wiki describes using 
independent_wallclock to sync domU clocks against the dom0 clock

http://docs.vmd.citrix.com/XenServer/4.0.1/guest/ch04s06.html

http://wiki.debian.org/Xen#Possible_problems_and_bugs-1

This sysctl appears to have gone away with squeeze, but the 
documentation is not updated

Time drift is observed running dom0 2.6.32 from squeeze, and a domU 
2.6.32-xen kernel from squeeze

Is there outstanding work required to support the independent_wallclock 
sysctl in squeeze, or is there just a documentation issue?

Your message dated Mon, 22 Aug 2011 13:47:25 +0200
with message-id <20110822114725.GA29601 at wavehammer.waldi.eu.org>
and subject line Re: [Pkg-xen-devel] Bug#638837: independent_wallclock sysctl
has gone away?
has caused the Debian Bug report #638837,
regarding independent_wallclock sysctl has gone away?
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner at bugs.debian.org
immediately.)


-- 
638837: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=638837
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems
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Subject: independent_wallclock sysctl has gone away?
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From: Bastian Blank <waldi at debian.org>
Subject: Re: [Pkg-xen-devel] Bug#638837: independent_wallclock sysctl has gone
away?
Date: Mon, 22 Aug 2011 13:47:25 +0200
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Thanks for the prompt reply about this.

There is no clear documentation (or discussion) of this issue that could 
be found in a web search.

Some of the pages I did find suggest that NTP on a domU is a bad idea, 
with one suggesting that the time goes backwards sometimes, interfering 
with some processes like Dovecot.  E.g:

http://wiki.dovecot.org/TimeMovedBackwards

Could you maybe elaborate on the situation or provide a link to the 
relevant mailing list discussion or README, to assist myself and anyone 
else who stumbles across this bug report?

Here is another page I stumbled across discussing a range of issues with 
clock sync and time zone, but like several pages I've seen, they suggest 
using a non-pv_ops kernel:

https://wiki.umiacs.umd.edu/VirtualMeshTest/index.php/Xen_clock_sync_issues

Could you comment on any of those issues, or maybe put something 
definitive about it in the Debian wiki for people using squeeze?