[Xen-devel] Memory management, mapping, paging questions...

[nicko.koinkoin@xxxxxxx]

First hello everybody,

Currently I play with Xen (2.0.7), especially I want to know more about
the memory management. What I understood is that at start-of-day, in the
start_info structure, we have the following information:

nr_pages = Number of machine pages provided for the virtual machine. Represents
           the amount of memory specified in the configuration file (nr_pages *
           4096).
pt_base  = The virtual address of the page directory.
nr_pt_frames = Number of page tables created for the VM by Xen
mfn_list = List of machine adresses.

So my questions are the following :

* pt_base is the virtual adress of the pd. But what means virtual here ? in
which adress space does this adress has the right meaning ?
* Does Xen create the page tables (I do not include the pd in page tables, I
think it is more understable like this, i.e. pd != pt) ? Where are these pt?
their address ?
* mfn_list : is this a list, starting at adress mfn_list, that contains all the
machine adresses of all machine pages allocated for our VM ? i.e. the following
code print all the machine page adresses :
       for (i = 0; i < nr_pages; i++)
              printf("page %d at %x\n", i, ((unsigned long *)mfn_list)[i]);
* If I want to map at identical (machine or physical adress == virtual address),
  how can I do ?

Thanks.

--
Nicolas CLERMONT
Xen player

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