Re: [Xen-devel] [PATCH 0 of 5] update xenctx to dump pagetables

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 21.06.11 at 11:59, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> Hi, 
> 
> At 17:56 -0400 on 20 Jun (1308592583), Konrad Rzeszutek Wilk wrote:
>> > Any ideas why some mfns are not accessible?
>> 
>> They look to be the special I/O PFNs. The ones that cover ACPI, framebuffer,
>> PCI IO bars, MP tale.
> 
> I think they're too high for that, but if you can post the e820 map of
> the system this happened on then we'll know. 
> 
>> > Are there any other paging states maintained outside of the guests
>> > memory?
>> 
>> They look to be I/O pages.
>> 
>> But not sure why they are mapped to your guest?
> 
> But they're not mapped into the guest - from the look of them they're
> not mapped anywhere.  You could add some extra printouts around that
> warning in mm.c to show whether the MFNs are valid and if so which
> domain owns them.
> 
> Also, interesting that it's the addresses just above 0xffff800000000000
> that are different - what lives at that address in the PV kernel you're
> running?

That's Xen's space, isn't it. Clearly any non-hypervisor based page
table walking code has to ignore this range for PV guests' page
tables.

Jan


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