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Re: [Xen-devel] Re: [PATCH] Xen Guest Kexec

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] Xen Guest Kexec
From: Gerd Hoffmann <kraxel@xxxxxxx>
Date: Mon, 06 Mar 2006 15:15:00 +0100
Cc: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Mark Williamson <mark.williamson@xxxxxxxxxxxx>, Horms <horms@xxxxxxxxxxxx>
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  Hi,

Ok, one of the more intresting issues is p2m map and ballooning, I'm not
sure yet how to address that best.

One problem are the "holes" in guest physical memory created by
ballooning.  The other one is the time gap between loading and booting
the kexec kernel (and the p2m table which may change inbetween).

My first attempt to address that issue by avoiding it
(features="auto_translated_physmap" ;) resulted in this:
kernel BUG at drivers/xen/balloon/balloon.c:216!

For now I have a few questions:

 * Which events can change the p2m map?  I think for domU that is only
   ballooning, right?  For dom0 additionally the backend drivers (when
   mapping foreign pages).  Anything else?
 * Is there some way to rebuild the p2m map from scratch using
   hypercalls?
 * Is there some easy way to "compress" the memory, i.e. move all pages
   to the start of (guest physical) memory?

 * Are unpriviledged domains allowed to do Dom0 ops for DOM_SELF?
   getdomaininfo for example?  Or hypercall_init?

cheers,

  Gerd

-- 
Gerd 'just married' Hoffmann <kraxel@xxxxxxx>
I'm the hacker formerly known as Gerd Knorr.
http://www.suse.de/~kraxel/just-married.jpeg

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