CPU Privilege Rings: Why rings 1 and 2 aren't used?

Question

A couple of questions regarding the x86 CPU privilege rings:

• Why aren\'t rings 1 and 2 used by most operating systems? Is it just to maintain code compatibi

Answer 1

According to Wikipedia’s page on Ring Security, rings 1 and 2 are used for drivers(ring 1), guest operating systems(ring 1), and i/o privileged code(ring 2), hypervisors sit in -1/0 (depending on the hyper-visor) not 1 as I previously stated.

However, the extra two rings never really helped and thus became rarely used. TBH, most code using rings 1 and 2 these have semi-repurposed them from their original use (such as the hypervisors). Most windows code these days seems to treat the system as only having two levels (kernel and user), probably due to the overhead associated with entering and leaving kernel land.