What is the difference between ring0 and ring1?
At the interview, they asked me the difference, but I couldn't answer.
What is the difference between ring0 and ring1? Why are they needed?
I was also advised to learn about two and three, but they said that it was difficult. I tried Googling, but it's in English and it's not clear.
Can someone explain clearly?
2 answers
These are the privilege levels of the process. Usually physically defined by a few bits in one of the CPU's control registers.
At level (ring, ring) 0, any processor (CPU) commands with any registers can be executed, at others only a subset of them.
Well.. in short, and in your own words - Ring0 or otherwise Kernel Mode - the highest level of privileges available in the OS, allows you to access protected resources - any data of any program in memory, perform I / O operations through any ports. Usually, no one except the OS kernel has such privileges. Ring3 or User Mode-Win API