paging crazyness

[DruG5t0r3]

I've seen this practice where a page directory entry would have his own address in it....basically a page pointing to itself. It's sorta mind bogling....anyone have some explaination on how the heck that works?

[viral]

see
www.osdever.net > Tutorial > MM tut by Tim Robinson

[AR]

By mapping the page directory to itself, all the page tables are made contiguous in memory, eg. Page Directory last entry equals page directory then accessing 0xFFC00000 will allow you to rewrite the page table for 0-4MB regardless of where it is. 4-8MB at 0xFFC01000 and so on.