Re: [Xen-devel] Confused about start of day setup

[Goswin von Brederlow <brederlo@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> writes:

> On 23/9/07 06:29, "Goswin von Brederlow"
> <brederlo@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>> Now here is an example output of this loop:
>> 
>> ERROR: -22 pinning failed: addr = 90000 [212000], op = 0, mfn = 212
>> ERROR: -22 pinning failed: addr = 91000 [0], op = 0, mfn = 0
>> ERROR: -22 pinning failed: addr = 92000 [b3d5000], op = 0, mfn = b3d5
>> ERROR: -22 pinning failed: addr = 93000 [2000], op = 0, mfn = 2
>> ERROR: -22 pinning failed: addr = 96000 [2000], op = 0, mfn = 2
>> ERROR: -22 pinning failed: addr = 97000 [1000000], op = 0, mfn = 1000
>> ERROR: -22 pinning failed: addr = 98000 [0], op = 0, mfn = 0
>> ERROR: -22 pinning failed: addr = 99000 [1000], op = 0, mfn = 1
>> ERROR: -22 pinning failed: addr = 9a000 [0], op = 0, mfn = 0
>
> The [phys] values look screwed. There are duplicates and many are 0! So it
> looks rather like your p2m lookup logic is broken somehow.
>
>  -- Keir

I can't fathom what could be wrong with this:

unsigned long *phys_to_machine_mapping;
phys_to_machine_mapping = (unsigned long *)start_info.mfn_list;

machine_address = phys_to_machine_mapping[(addr - VIRT_START) >> PAGE_SHIFT] << 
PAGE_SHIFT;

The code is too simple and it works for all other pages outside that
one range. No I don't think it is this piece of code. But if there is
nothing to be there than the data itself must be corrupt. Although I
can't think of anything that could be overwriting that
phys_to_machine_mapping array.

Maybe I could hack the domain creator to map the array read-only and
see if I get a segfault?

MfG
        Goswin

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