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Re: [Xen-devel] HVM save/restore issue

To: "Zhai, Edwin" <edwin.zhai@xxxxxxxxx>, Ewan Mellor <ewan@xxxxxxxxxxxxx>, Tim <Tim.Deegan@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] HVM save/restore issue
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Tue, 20 Mar 2007 08:29:30 +0000
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On 20/3/07 08:12, "Zhai, Edwin" <edwin.zhai@xxxxxxxxx> wrote:

> latest HVM save/restore break again:(
> i use the memsize(the number in the xmexample.hvm) deduced from
> 'memory_static_min' to calculate some HVM PFNs when restore.

Out of interest: why would you do this? I glanced upon the code you are
referring to in xc_hvm_restore.c yesterday, and it struck me as particularly
gross. All three PFNs (ioreq, bufioreq, xenstore) could be saved in the
store after building the domain and then saved/restored as part of the
Python-saved data. The situation is easier than for a PV guest because PFNs
do not change across save/restore.

The more assumptions about memory layout we bake into xc_hvm_{save,restore}
now, the more we have to unbake when the HVM memory map becomes more dynamic
(balloon driver support, in particular). Making these assumptions to some
extent for now is okay, but we should avoid it where possible.

 -- Keir

> but now, 'memory_static_min' becomes 0 since r14425 and memsize is not
> recorded 
> in the saved configuration(memory_static/dynamic_min/max...) any more.
> do we have any reason to change the guest configuration so frequently?
> do you have any other suggestion to get the memsize from configuration?

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