Rings 1 and 2

[lopidas]

Is there some privilege difference between these two?
And of course then privilege difference between 0 and 1, 2 and 3?

My thoughts (maybe I am absolutely wrong): It is for combining user-mode in ring 3 with driver in ring 2 and kernel mode ring 0 with driver in ring 1
Edited thoughts: ring 2 seems to be in kernel-mode too

[AJ]

Hi,

Yes there are privilege differences, but the reasons for using rings 1 and 2 evaporate when you start using paging, which only has the concept of 'User' and 'Supervisor' levels and you therefore only use rings 0 and 3.

Cheers,
Adam

[lopidas]

Hi,
does anyone know link to exact description of differences?

[AJ]

http://www.lmgtfy.com/?q=intel+software ... per+manual

[lopidas]

http://download.intel.com/products/proc ... 325462.pdf 15.5.1

[Casm]

Is there some privilege difference between these two?
And of course then privilege difference between 0 and 1, 2 and 3?

My thoughts (maybe I am absolutely wrong): It is for combining user-mode in ring 3 with driver in ring 2 and kernel mode ring 0 with driver in ring 1
Edited thoughts: ring 2 seems to be in kernel-mode too

The original reason for having four privilege levels was that the American military wanted it. Only ring 0 counts as kernel mode. You will get a general protection error if you try to execute privileged instructions in rings 1 or 2.