RE: pentium 4MB pages question for you MMU hackers

Michael Nelson (
Fri, 3 Jan 1997 18:42:34 -0500

>The Intel CPUs (and most other CPUs that do multitasking) have what are
>called "rings" which describe what kind of access the process can get to
>the CPU. The lowest ringlevel (ring 0) is your kernel and driver code.
>Most other CPUs only have 2 ringlevels, but Intel 32-bit CPUs (the 386 and
>up) have 4 ringlevels, but no one has ever put anything but rings 0 and 3
>to use.

That's not true at all, there are several operating systems that have put the other rings to use. QNX and OS/2 to name a couple.