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Chapter 2.2 - Linux Kernel

Learning Objectives​

By the end of this chapter, you will be able to:

  • Understand the role of the Linux Kernel
  • Explain how the Kernel manages resources
  • Understand system calls (syscalls)
  • Identify interactions with hardware

What is the Linux Kernel?​

The Linux Kernel is the heart of the operating system. It acts as an interface between hardware and software, managing all system resources.

Roles of the Kernel​

1. Process Management​

The Kernel creates, schedules, and terminates processes:

  • Creation: fork(), clone()
  • Scheduling: Scheduler (CFS - Completely Fair Scheduler)
  • Termination: exit(), kill()
  • Communication: pipes, sockets, signals

2. Memory Management​

The Kernel manages physical and virtual memory:

  • Allocation: malloc() → kmalloc()
  • Virtual memory: Paging, swap
  • Protection: Separation of memory spaces
  • Cache: Buffer cache, page cache

3. File System​

The Kernel manages file access:

  • VFS: Virtual File System (unified interface)
  • Multiple FS support: ext4, xfs, btrfs, etc.
  • Permissions: Access rights verification
  • Cache: Performance improvement

4. Network Management​

The Kernel manages network communications:

  • TCP/IP Stack: Protocol implementation
  • Network interfaces: eth0, wlan0, etc.
  • Firewall: iptables, netfilter
  • Routing: Routing tables

5. Device Management​

The Kernel manages hardware devices:

  • Drivers: Drivers for each device
  • Plug and Play: Automatic detection
  • Power management: ACPI, suspend/resume
  • Interruptions: IRQ management

System Calls (Syscalls)​

Applications communicate with the Kernel via system calls:

Examples of system calls:

  • open(): Open a file
  • read(): Read from a file
  • write(): Write to a file
  • fork(): Create a process
  • exec(): Execute a program
  • socket(): Create a network socket

Kernel Architecture​

The Kernel is organized into modules:

Types of modules:

  • Core: Essential features (always loaded)
  • Modules: Optional features (loaded on demand)
  • Drivers: Hardware drivers

Summary​

In this chapter, you learned:

Linux Kernel: Heart of the system, hardware/software interface
Roles: Process, memory, file, network, device management
System calls: Interface between applications and kernel
Architecture: Core + modules + drivers
Modules: Dynamic loading of features

Next Steps​

Chapter 2.3: Memory Management and Swap
Chapter 2.4: Virtual File System (VFS)

Chapter created on: December 2024