Modern operating systems are based on a memory model called VM. This includes Linux, Unixes, MS Windows, and macOS. Truly understanding how a modern OS works under the hood requires a deep understanding of VM and memory management – not topics we delve into in intricate detail in this book; nevertheless, a solid grasp of VM concepts is critical for Linux system developers.
Virtual memory
No VM – the problem
Let's imagine for a moment that VM, and all the complex baggage it lugs around, does not exist. So, we're working on a (fictional) pure flat physical memory platform with, say, 64 MB RAM. This is actually not that unusual – most old OSes (think DOS) and even modern Real-Time Operating Systems...