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

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 23/11/06 6:53 pm, "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx> wrote:

>> Pagetables etc. are all in 'p' address space, so there should
>> be no need for p2m or m2p in that case I think
>> 
>> 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!
> 
> Trouble is, the PV guest hasn't done an orderly suspend, and may be
> holding machine address references in registers/memory and in pagetables
> that haven't been pinned yet.
> 
> The guest's core dump will already contain the p2m table, and its root
> location has been registered with xen during boot, so this just needs to
> be saved too.

It's questionable how useful the ability to m2p-translate those marginally
possible bits of state is though. Currently the p2m table is used *only* to
construct an m2p table allowing pagetable walks in xc_ptrace_core().

 -- Keir


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