sumit sahu <sahusumit2001@yahoo.co.in> writes: > hi all, > could someone please explain me the significance of > _PAGE _PROTNONE flag of a page table entry. > thanx > sumit Check out the definition of pte_present and the comments for the bits. If I recall correctly, when you mprotect a page to PROT_NONE, the page is marked as absent in the page tables and the _PAGE_PROTNONE bit is set. That way, if the user app tries to access the page, the hardware sees that the page is marked as not present and invokes the kernel exception handler. The kernel knows, though, that if the _PAGE_PROTNONE bit is set, then the page really is present. -- --Ed L Cashin | PGP public key: ecashin@uga.edu | http://noserose.net/e/pgp/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
