From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH v4 0/9] toolstack-based approach to pvhvm
 guest kexec
Date: Thu, 11 Dec 2014 16:30:29 +0100
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	<20141211142428.GA19820@aepfle.de> <5489B721.6010504@citrix.com>
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To: David Vrabel <david.vrabel@citrix.com>
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On Thu, Dec 11, David Vrabel wrote:

> Nothing special needs to be done with ballooned pages.  If frames are
> not populated in the original domain, they will be unpopulated in the
> new domain.
> 
> It's the responsibility of the guest to ensure it either doesn't kexec
> when it is ballooned or that the kexec kernel can handle this (e.g., by
> using a crash region that is never ballooned out).

There is a difference between kexec and kdump. The kdump kernel does not
care because there is code in /proc/vmcore to handle ballooned pages in
the crashed kernel gracefully.
But a kexec boot will likely access pages which are not backed by RAM.
Unfortunately there is no flag left to mark a page as ballooned.

So what you are saying means that kexec-tools needs to continue to
balloon up before doing the actual kexec. I had hoped this suggested
approach would get rid of that limitation.

Olaf