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Re: does pmd_offset return the physical address or virtual address of the page table?

Hi Tsai,
   The Page Table Entries contain physical addresses. The PGD and PMD
entries are always present whereas as the PTE entries can be in memory
or swap. But the xxx_offset macros return the virtual address as they
use __va(address) to convert these physical addresses to virtual
addresses. This can be done because these are valid kernel virtual
addresses.

-------------
Raj.

On Apr 6, 2005 6:02 PM, nitin ahuja <nitin2ahuja@xxxxxxxxxxxxx> wrote:
> This is what Mel Gormen says:
> 
> pgd_offset() takes an address and the mm_struct for the process and returns the PGD entry that covers the requested address. pmd_offset() takes a PGD entry and an address and returns the relevant PMD. pte_offset() takes a PMD and returns the relevant PTE.
> 
> Physical address space is flat, no concept of PGDs, PMDs and PTEs. So, the address returned by pmd_offset is virtual address as one would access it inside kernel.
> 
> Nitin
> 
> 
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Kernelnewbies: Help each other learn about the Linux kernel.
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