Is the Operating System a process?

Question

I am just now learning about OSes and I stumbled upon this question from my class' lecture notes. In our class, we define a process as a program in execution and I know that an OS is itself a program. So by this definition, an OS is a process.

At the same time processes can be switched in or out via a context switch, which is something that the OS manages and handles. But what would handle the OS itself when it isn't running?

Also if it is a process, does the OS have a process control block associated with it?

There was an older question on this site that I looked at, but I felt as if the answers weren't clear enough to really outline WHY the OS is/isn't a process so I thought I'd ask again here.

Answer 1

First of all, an OS is multiple parts. The core piece is the kernel, which is not a process. It is a framework for running processes. In practice, a process is more than just a "program in execution". On a system with an MMU, a process is usually run in its own virtual address space. The kernel however, is usually mapped into all processes. It's always there.

Other ancillary parts of the OS exist to make it usuable. The OS may have processes that it runs as part of its management. For example, Linux has many kernel threads that are independently scheduled tasks. But these are often not crucial to the OS's operation.