Physical address of Page Table Entries

Mark Wallace lotabout at gmail.com
Fri Nov 8 20:37:32 EST 2013


Hi all,

*Question: *
When we use 2 level paging(Directory+Table+Offset), does the page table
entries have to be put exactly on the beginning of a page frame?

*Description: *
The format of Page Directory and Page Table are the same. And they all
contain 20 bits as a pointer to the next level entries.

For Page Table entry, I understand that 20 bits is enough because page
frames are 4k aligned. But for Page Directory entry, the 20 bits should be
the address of a Page Table, that means the physical address of a Page
Table entry should be 4k aligned too. And thus they may only exist at the
beginning of a page frame.

Is this right or am I missing something?

Thanks.
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