Hi all, AFAIK, for IA-32 arch, two-level paging is sufficient. But the positions of PUD and PMD are kept. In the book "Understanding the Linux Kernel, 3rd", it said that kernel set the number of the entries of PUD and PMD to 1 and mapping these two entries into the proper entry of the Page Global Directory. I don't quite understand the word "mapping". Does that mean there is one entry in PGD for both PUD and PMD? What do they used for? I think the hardware only knows there's two-level paging, so whatever in the entry of PUD and PMD doesn't matter to the hardware. Am I right? Could anyone give me some explain? I wanna look through the source code of paging mechanism, but don't know where to start. Some clues? Thanks a lot! -- Wu Yu -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ