Linux Architecture Explained from Scratch (Beginner Friendly Guide)

 

Linux architecture – internal structure and layered working explain

To understand Linux architecture, you should first know the basic that what Linux is.

In this blog, we learn about Linux architecture working, from basic to advance level. It’s a basic guide for beginners who wants to learn about Linux and its architecture. Understanding Linux architecture helps you to know how Linux OS runs applications, manages memory for application, interaction with hardware, and provides services and many more.

Linux is an open source and Unix-like operating system that manage hardware and software resources. Meanwhile Linux architecture is the internal structure of that operating system. It is the most powerful operating system.

What is Linux Architecture?

Linux architecture is the internal layer design of Linux OS, its shows you how the components of Linux architecture like hardware layer, kernel layer, system library layer and application layer work together to perform computer tasks, it follows the Unix-like architecture, means it’s a layer based model. Each layer work independently which makes it flexible and efficient.

So let’s break down how Linux architecture layers work, Linux architecture are divided into four main layers:

• Application layer­­
• System library layer
• Kernel layer
• Hardware layer

Let’s briefly understand each layer.

Application layer

This is the top layer of Linux architecture, in this layer user directly interact with applications. User do not directly communicate with the hardware instead users only interact with the applications. This layer include application and software programs like web browser, Firefox, Chrome, office suit, text editors, games and multimedia applications.

Let’s understand this with real time example:

So there is a user who clicks on the Chrome browser, the user does do not communicate with the hardware that’s why the click of the user on chrome icon activates application layer, The Chrome browser runs in the application layer it provides the user interface (address bar, tabs)

Now after this the chrome needs some resources like CPU, RAM, network and display.

So the Chrome request that I need resources for performing user task.

 

System library layer

The system library layer acts as a middle layer .It is a bridge between the applications programs and kernel, the application to do not directly access the kernel so they use library function to connect with kernel.

Let’s understand this with real time example

Let’s continue the previous example:

Now the chrome do not directly communicate with the kernel for resources so it used system libraries like (glibc).

So the libraries convert the kernel complex command into simple functions, it gives the easy functions like print, open file, read data. Now user wants to read a file on chrome, chrome sends a request to the kernel through a system call, and system calls generate by system libraries.

Kernel layer

The kernel is the core part of Linux operating system.it is a bridge between hardware and software and it directly manages the hardware. Functionalities of kernel are given below:

1. Process management

It manages the CPU time of applications (chrome, word) and if you open multiple application on computer system it also decide which applications runs first.

2. Memory management

It allocate the RAM between applications and also handle extra data using virtual memory and paging.

3. File system management

It manages the application’s file reading, writing and storage and save it on hard disk.

4. Device management

Kernel controls hardware devices using device drivers, like printer driver, graphics driver. Also Mouse, keyboard, screen, Network card (internet) are manages by device management.

5. System calls

It provides an interface for communication between applications and hardware.

 

Let’s understand this with real time example

When the kernel receives a request of chrome (via system libraries). It decides how to carefully manage all the resources of chrome.

When you open chrome, the kernel creates a new process for chrome, assigns CPU time so it can run, allocates RAM to store temporary data, allows access to network devices, and sends output to the display.

All of this happens within milliseconds.

Hardware layer

This is the bottom layer, this layer cannot directly contact with user even it provide resources through the kernel, Hardware does not make decisions. It only executes instructions given by the kernel. It include all the physical devices like:

• CPU
• RAM
• Hard disk
• Input devices
• Output devices

All these devices follows kernel instructions.

 

Complete flow of Linux architecture

When user open chrome, they are at application layer, the chrome does not know what to do after user click, then chrome request for resources, So it uses system libraries which translate the application’s (chrome) requests into a form that kernel understand easily.

System library sends a request to the kernel, now the kernel decides which resources allocate to chrome, it manages the CPU time, RAM, which device to use, and output should appear on the screen with kernel functionalities like process management, memory management, device management, and file system management.

Then the kernel discuss all these decisions to the hardware in the form of machine instructions after allocate all the resources to chrome, user finally see the display appear on monitor.

User → Application layer → System Libraries layer → Kernel layer → Hardware layer → Output

 

Some interview questions to remember

1. Define Linux Architecture?

Answer:
Linux Architecture is a layer structure of the Linux OS in which multiple components work together to manage hardware resources and provide services to applications.

2. Define all main layers of Linux Architecture?

Answer:
The four main layers of Linux Architecture are:

1.  Hardware layer

2.  Kernel layer

3.  System Libraries layers

4.  Application Layer

3. Define the role of the Kernel in Linux?

Answer:
The kernel is the major component of Linux. It manages CPU, RAM, files, and devices, and also acts as a bridge between software applications and hardware.

4. Can applications directly contact hardware in Linux?

Answer:
they cannot directly access hardware. They communicate with hardware using system libraries and the kernel.

5. Define the system libraries in Linux?

Answer:
System libraries provide secure interface for user that allows applications to use kernel services without directly interacting with the kernel.

6. Differentiate between User Space and Kernel Space?

Answer:
User space is where software applications like (chrome, Word, notepad) and libraries run, while kernel space is where the kernel and device drivers run. Because User space programs cannot directly access kernel space.

7. Define system call?

Answer:
A system call is a program that allows an application to request services from the kernel, such as reading a file or allocating memory etc.

8. Explain process management in Linux?

Answer:
Process management is a kernel function that controls, creates, schedules, and terminates processes and allocates CPU to each process.

9. Explain memory management in Linux?

Answer:
Memory management is handle by kernel and includes allocation and deallocation of RAM securely.

10. What you mean by virtual memory?

Answer:
Virtual memory is a technique in which the kernel uses disk space as an extension of RAM when physical memory is insufficient.

11. What are device drivers?

Answer:
A device driver is a software component that enables communication between the kernel and hardware devices. Devices like (mouse, keyboard, printer) etc.

12. Role of the file system in Linux?

Answer:
The file system organizes, stores, and manages data on storage devices and controls file creation, reading, writing, and deletion.

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Conclusion

Linux Architecture is a layer structure that provides safe and efficient communication between the user, kernel, software, and hardware. In this architecture, users cannot directly interact with the hardware even all tasks are performed through applications layer.

Because of the layer design of Linux IT is fast, secure, reliable, and widely used as an operating system around the world.