FreeBSD 10-BETA4 r258899 PVHVM Xen clock -> 1970 on VM migration

[Adam McDougall]

On Fri, Dec 06, 2013 at 06:36:17PM +0100, Roger Pau Monné wrote:

  On 06/12/13 18:14, Adam McDougall wrote:
  > Hello,
  > 
  > I noticed on recent (PVHVM) builds of FreeBSD 10 that I randomly lose the
  > proper date/time when I migrate my VM from one XenServer to another in the
  > pool.  I was intending to reproduce a much smaller time difference I've seen
  > on 9 but this was a much bigger jump so I started concentrating on the big
  > jumps.  When I migrate my VM back and forth between two servers, it will
  > randomly jump to a date in 1970 or 1969.  Continued migrations often bring
  > the proper date/time back, but there is not a strong pattern.  The 1970
  > comes and goes.  I could not reproduce this kind of jump on 9.  This happens
  > on XenServer 6.0 and 6.2.
  
  Hello,
  
  Thanks for testing, there were some bugs in Xen regarding the migration
  of PVHVM guests, the one that comes to mind, and that could cause this
  kind of time disruption is:
  
  http://lists.xenproject.org/archives/html/xen-devel/2013-06/msg01110.html
  
  The patch should be present in at least Xen 4.3, not sure about previous
  versions. Is there anyway you could try this on a recent Xen version (4.3)?

It seems fine in 4.3, I installed the 2013-12-05 ISO on 
http://www.xenserver.org/overview-xenserver-open-source-virtualization/download/2-uncategorised/115-development-snapshots.html
which identifies itself as 6.2.50.  I migrated a VM about 8 times.  It did
become off by a couple seconds but ntpd should fix that up.
  
  > I will take a stab at trying PVH time permitting,
  > but since 10.0 will ship with PVHVM it seems appropriate to try to fix it
  > if possible.  Let me know if there is more testing or information gathering
  > I should do.  Thanks.
  
  Xen 4.4 will be the first version to support PVH, which has not yet been
  released, and right now doesn't support migration. If you could try a
  recent version of Xen that contains the mentioned patch it will
  certainly help diagnose it (or at least make sure it's caused by this
  issue).
  
  Roger.
  
Sorry, I missed the part in your original email about needing Dom0 changes for
PVH.