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Re: [Xen-devel] Page tables in Xen

  • To: "Haifeng He" <hehaifeng2nd@xxxxxxxxx>
  • From: Satya <satyakiran@xxxxxxxxx>
  • Date: Thu, 29 Nov 2007 09:58:56 -0600
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 29 Nov 2007 07:59:33 -0800
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On Nov 28, 2007 4:49 AM, Haifeng He <hehaifeng2nd@xxxxxxxxx> wrote:

I have a question about memory page tables in Xen. As far as I
understood, every modification
to page table will go through Xen(hypervisor).

that is correct.  The hypervisor must know (and validate) all page table updates.

Is it so that all page
tables are actually allocated
in Xen(hypervisor) instead of guest OS(domain)?

Nope. For page tables, the guest domain has to allocate pages from it's own memory pool. The guest domain must then inform the hypervisor about these pages so that Xen knows that they are page-table pages.
Also, is it the case
that Xen(hypervisor) needs to
maintain a page table for each process running in every domain?

No. Each domain maintains it's own page tables for processes. The hypervisor only needs to know which physical pages contain page table entries.




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