After this documentation was released in July 2003, I was approached by Prentice Hall and asked to write a book on the Linux VM under the Bruce Peren's Open Book Series.

The book is available and called simply "Understanding The Linux Virtual Memory Manager". There is a lot of additional material in the book that is not available here, including details on later 2.4 kernels, introductions to 2.6, a whole new chapter on the shared memory filesystem, coverage of TLB management, a lot more code commentary, countless other additions and clarifications and a CD with lots of cool stuff on it. This material (although now dated and lacking in comparison to the book) will remain available although I obviously encourge you to buy the book from your favourite book store :-) . As the book is under the Bruce Perens Open Book Series, it will be available 90 days after appearing on the book shelves which means it is not available right now. When it is available, it will be downloadable from http://www.phptr.com/perens so check there for more information.

To be fully clear, this webpage is not the actual book.

4.4 Translating and Setting Page Table Entries

This set of functions and macros deal with the mapping of addresses and pages to PTEs and the setting of the individual entries.

mk_pte() takes a struct page and protection bits and combines them together to form the pte_t that needs to be inserted into the page table. A similar macro mk_pte_phys() exists which takes a physical page address as a parameter.

pte_page() returns the struct page which corresponds to the PTE entry. pmd_page() returns the struct page containing the set of PTEs.

set_pte() takes a pte_t such as that returned by mk_pte() and places it within the process's page tables. pte_clear() is the reverse operation. An additional function is provided called ptep_get_and_clear() which clears an entry from the process page table and returns the pte_t. This is important when some modification needs to be made to either the PTE protection or the struct page itself.