Sorry if this is a stupid question. I couldn't find the answer anywhere :/. My question is this:

What is the difference in the rings?

ring0 - ? (protected)
ring1 - ?
ring2 - ?
ring3 - ? (applications)

I've read some on rings 0 & 3, but what are 1 and two used for (if at all)? Thanks.
Posted on 2001-12-17 18:30:38 by lackluster
Under Win32 only ring0 and ring3 is used.
386+ prc gives possibility to use 4 rings of priviledge but its upto OS which of them to use.
It gives protection on hardware level. Stone looks at desc table
and giving access to data and some system registers according to the preveldge level. 0 is the highest 3 is the lowerest.
Thread of curtain prevelege is grunted access to regions of the same prividge or lower.
Posted on 2001-12-18 04:04:35 by The Svin
IMO ring1 and 2 aren't too useful, as they don't add much extra
protection. And to use them, you have have to add additional code.
Use segments. And more (slow!) ring switches. And page tables
only has concept of user/supervisor.
Posted on 2001-12-18 10:31:09 by f0dder