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RE: [Xen-devel] Domain save/migrate issue

  • To: "Anthony Liguori" <aliguori@xxxxxxxxxx>
  • From: "Noam Taich" <noam.taich@xxxxxxxxxxxx>
  • Date: Wed, 15 Feb 2006 08:22:51 -0800
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Wed, 15 Feb 2006 16:35:26 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcYyOoUYzSmpah4BQNeCRKX9/z0BgQADysog
  • Thread-topic: [Xen-devel] Domain save/migrate issue

>Suspend does more than just canonicalize the p2m, it also provides 
callbacks for all of the devices so that they can canonicalize their own

page references and set them self up to reinitialize upon resume.

>While the save code can access the p2m table, it has no way of knowing 
the device information so just pausing isn't really an option (also, you

could do bad things like checkpoint before a storage operation was 
committed or something like that).


>Anthony Liguori

Ok. So pause ALONE is not possible. But I didn't mean I'd do only a

Suspend writes all the info you just mentioned. And the save code just 
writes the info that suspend left for it.
So, lets tackle the problem in xen and/or the host.

If a change was entered into the suspend code, say, a special mode,
"pseudoSuspend" was added, in which the function writes all that same
Into that very same place it wrote to before (or any other cozy spot we
can access from the save function), but does NOT actually suspend the
(Ideally, it would suspend nothing. But, if necessary, it can resume
everything instead of calling the actual shutdown code).

The save function doesn't need to know anything now that it didn't know

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