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Re: [Xen-devel] pagetable pinning question


I'm a bit confused by parts of the discussion going here. Can anyone
explain the difference between linear page table and normal page table?
Linux page tables are all linear, i.e. contiguous page table entries
correspond to contiguous virtual pages. Is this right? How about

How can one page directory be mapped from another page directory?

My understanding is: (maybe wrong) each process has only one
page directory and 1024 page tables. Each page directory and page
table fits into one page (on 32-bit computers with 4k page size).
Not all page tables are allocated physical page frames initially. During
a context switch from process A to process B, A's PD and PTs can be
swapped out (in face of memory shortage), releasing physical page
frames for use by B. So, how can one PD be mapped by another PD?

What am I missing here?


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