Xen devel - Nov 2007 - map_domain_va and map problem with address mapped.

Hi

I have some problem about access a guest location memory using 
map_domain_va function. My situation is next:

I have a simple program running in domU, I retrieve a guest virtual 
address for a struct value and I pause the domain (when I pause the domU 
the interested program still run...).

So I call map_domain_va function that call map_domain_va_pae. It seems 
that everything works properly because I obtain an address (PT walk 
don''t fails...), but If I try to access this address I find a
"strange"
value.

For example:

domU guest address: 0xbfd38838 a location that contains an int, for 
example 10.

Address mapped returned by map_domain_va: 0xb7fac838

If I access the pointer returned above I obtain: 0xbfd38858 (very 
similar to domU guest address...). Perhaps I did not understand 
something, but I should not obtain 10?

Tnx in advance.

Best Regards

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> I have some problem about access a guest location memory using
> map_domain_va function. My situation is next:
>
> I have a simple program running in domU, I retrieve a guest virtual
> address for a struct value and I pause the domain (when I pause the domU
> the interested program still run...).
>
> So I call map_domain_va function that call map_domain_va_pae. It seems
> that everything works properly because I obtain an address (PT walk
> don''t fails...), but If I try to access this address I find a
"strange"
> value.
>
> For example:
>
> domU guest address: 0xbfd38838 a location that contains an int, for
> example 10.
>
> Address mapped returned by map_domain_va: 0xb7fac838
>
> If I access the pointer returned above I obtain: 0xbfd38858 (very
> similar to domU guest address...). Perhaps I did not understand
> something, but I should not obtain 10?
Yeah, I agree you should get 10, and what you''re doing sounds right. 
It seems
strange.

Can you post some relevant snippets of your code (both in the domU and dom0) 
and maybe the problem will become apparent when we can all have a look at it?

Cheers,
Mark


-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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