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Re: [Xen-devel] xc_get_pfn_list() creates broken core files

To: Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] xc_get_pfn_list() creates broken core files
From: John Levon <levon@xxxxxxxxxxxxxxxxx>
Date: Thu, 23 Nov 2006 19:17:32 +0000
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On Thu, Nov 23, 2006 at 06:39:11PM +0000, Keir Fraser wrote:

> On 23/11/06 18:16, "John Levon" <levon@xxxxxxxxxxxxxxxxx> wrote:
> 
> >> Save out the guest's own p2m table.
> > 
> > OK. What about HVM?
> 
> Pagetables etc. are all in 'p' address space, so there should be no need for
> p2m or m2p in that case I think

Sure, but I still need to map the domain pages, so I still need
xc_get_pfn_list() in this case, right? Will it work?

> In fact pagetables could be canonicalised into 'p' space for PV guests too
> (xc_linux_save has the code for this) then there'd be no need to dump the
> p2m table in the core dump at all. Save format and core dump format should
> probably be one and the same!

They should indeed be essentially the same format. But I'm not fond of
the idea of canonicalisation; it makes certain things impossible to
debug as you've lost all notion of what the pagetables /really/ were.
And there will be cases the domain is stuck in some HAT routine and I
really want to know what that local mfn variable refers to.

regards,
john

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