🚀 go-pugleaf

In article <43367@ames.arc.nasa.gov> lamaster@ames.arc.nasa.gov (Hugh LaMaster) writes:
>1) Several posters have mentioned that there is some unspecified but obvious
>(to them) major problem with using inverted page tables together with
>memory mapped files.  I wonder if someone could enlighten us regarding
>this problem, since apparently it isn't obvious to every system architect :-)

The big problem is with sharing.

The word "inverted" is used, because the table is a map from physical
addresses to virtual addresses. More precisely, you use an array, and
use physical page numbers as subscripts. Each table entry tells you
what virtual page is mapped to there.

SO: only one page can be mapped to there. Unless, of course, the OS
goes through a fair bit of grief to make the machine work right in
spite of its design.



-- 
Don		D.C.Lindsay 	Carnegie Mellon Computer Science