theory_on_paging

references :

• https://os.phil-opp.com/paging-introduction/

Supervisor mode in riscv introduces a paging system that pages the physical memory.
But before we discuss the paging system that is specific to RISCV, we need to understand paging theory by itself.

Virtual addresses and Phsical addresses

Before we discuss paging, let's first find out what virtual addresses and physical addresses are.

A Physical memory address is the constant and full address of a physical space in memory. It is the address pf a physical space in memory. Each physical memory address is unique. And each physical address represents a single unique physical space.

A virtual memory address is like a variable that contains the Physical memory address as its value. Just like in programming, variables are unique only in a certain scope. Different variables can contain the same value... the same way different virtual addresses can represent the same physical memory addresses.

A virtual address can be translated to its equivalent physical address.
We need virtual addresses so that we can manipulate memory just like how we manipulate variables.
Virtual Addresses are a way of abstracting the physical memory.