[vbox-dev] Translating different types of memory addresses in virtual box

[Knut St. Osmundsen]

On Feb 14, 2010, at 17:49, mgofman1 at binghamton.edu wrote:

> I analysed the return codes; they were either -1004
> (PAGE_TABLE_NOT_FOUND) or -31 (PAGE_NOT_FOUND). I guess it was the  
> addresses that I supplied.
>
> I tried converting all virtual addresses from 0 to 10000000000 to  
> physical and got valid conversions for many of them (while many  
> others still returned error codes).  So I think the issue is as I  
> said the addresses that I supplied.
>
> So what I am trying to understand is the relationship between the  
> VirtualBox virtual addresses and guest virtual addresses. I.e.  
> suppose that in the guest I get the virtual address xxxx from proc  
> file system or what not. Now, in the VirtualBox, if I use  
> PGMPhysGCPtr2GCPhys function to convert address xxxx to physical, it  
> should work, and the physical address should correspond to the  
> actual guest physical address. So reading something from this  
> physical address inside the guest or in VirtualBox should give the  
> same result.
>
> When I try to do the above, ie get the virtual address inside the  
> guest from proc file system, and try to translate that address to  
> physical in VirtualBox using PGMPhysGCPtr2GCPhys it gives me  
> PAGE_TABLE_NOT_FOUND.  So it seems that there is not a one-to-one  
> relationship between the virtual addresses which guest sees and what  
> VirtualBox sees.
>
> Is my understanding of the above correct? Or I am I doing something  
> wrong?


My guess is that you are disregarding the memory context of the guest  
virtual address.

--

Kind regards / Mit freundlichen Gruessen / Vennlig hilsen,
   Knut

--

Sun Microsystems GmbH        Knut St. Osmundsen
Werkstrasse 24               Senior Staff Engineer, VirtualBox
71384 Weinstadt, Germany     mailto:bird at sun.com

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