Full Structure of Operating System Kernel Explained (With Diagrams)

🧩 Introduction: What is a Kernel?

The kernel is the core part of an operating system that acts as a bridge between hardware and software applications.

It manages:

• CPU execution
• Memory allocation
• Device communication
• System resources

Without the kernel, software cannot directly interact with hardware.

---

🧱 Overall Kernel System Structure

Here is a simplified view of how the kernel sits inside an operating system:

🧠 Key Layers:

1. User Applications
2. System Libraries
3. Kernel Space
4. Hardware Layer

---

⚙️ Core Components of Kernel

1. 🧵 Process Management

Handles execution of programs.

• Creates and destroys processes
• CPU scheduling
• Context switching

👉 Example: Running Chrome and VS Code simultaneously

---

2. 🧠 Memory Management

Controls RAM usage efficiently.

• Allocates memory to processes
• Handles virtual memory
• Prevents memory conflicts

---

3. 📂 File System Management

Manages files and directories.

• File creation/deletion
• Permissions handling
• Storage organization

---

4. 🔌 Device Management (I/O System)

Acts as a translator between hardware devices and software.

• Printer, keyboard, disk handling
• Device drivers
• Interrupt handling

---

5. ⏱ CPU Scheduling

Decides which process gets CPU time.

Common algorithms:

• FCFS (First Come First Serve)
• Round Robin
• Priority Scheduling

---

6. 🔐 Security & Protection

Ensures system safety.

• User authentication
• Access control
• Process isolation

---

🧠 Types of Kernel Architecture

1. 🧱 Monolithic Kernel

Everything runs in kernel space.

✔ Fast performance ❌ Hard to maintain

Examples: Linux, UNIX

---

2. 🧩 Microkernel

Only essential services run in kernel.

✔ More secure ❌ Slightly slower due to communication overhead

Examples: Minix, QNX

---

3. ⚡ Hybrid Kernel

Combination of both monolithic + microkernel.

✔ Balanced performance and modularity Examples: Windows NT, macOS

---

🔄 How Kernel Works (Step-by-Step)

1. User runs an application
2. System call is made to kernel
3. Kernel processes request
4. Kernel interacts with hardware
5. Result is returned to application

---

📊 System Call Interface

System calls are the gateway to kernel services.

Examples:

• read()
• write()
• fork()
• exec()

---

⚡ Why Kernel is Important?

Without kernel:

• No multitasking
• No hardware communication
• No memory protection
• No file system

---

🧾 Conclusion

The kernel is the heart of every operating system. It ensures communication between hardware and software while managing resources efficiently. Understanding kernel architecture helps in OS development, system programming, and low-level engineering.

---