Understanding the Linux Kernel [Detailed Guide]


Linux kernel is a monolithic kernel; thus, it has the largest footprint and is highly complex. Unlike other kernels, Linux kernels can be loaded and unloaded at runtime. This means you may add or remove features of your kernel as you please. 

The complexity of the Linux kernel makes understanding it even more important. This article provides information to help you comprehend the Linux kernel. Read on.

What is the Linux Kernel?

The Linux kernel a major component of the Linux operating system. It interfaces between your computer’s hardware and its processes. It manages resources efficiently and communicates between the hardware and its processes. It is the core component of your Linux operating system(source).

It exists within the operating system and controls all the hardware’s major functions in whatever device. By virtue of being a monolithic kernel, Linux kernels have better access to the hardware and are great at multitasking. 

The Linux Kernel Relationship with Your Hardware

The Linux kernel manages your system’s hardware through what is known as interrupts. An interrupt helps the hardware interface with the system by is issuing a signal that interrupts the processor. The kernel can disable interrupts to aid synchronization, be it only one or all of them. 

In Linux, the interrupt handlers are not run in a process context; rather, they are run in the form of an interrupt context unassociated with other processes. This interrupt context exists only to allow the interrupt handlers to respond swiftly to an individual interrupt and finally exit.

What Does Linux Kernel Do?

The kernel can be described as an assistant to the hardware. It relays messages and requests (processes) from the users to the hardware. This interfacing activity controls what has been stored in the memory and regulates access to the hardware at any given time.

The Linux kernels function can be categorized and grouped into: 

Communication Management – The Linux kernel supports communication between the hardware via drivers. These drivers may be included in the kernel or added to the kernel via kernel modules and the software.

Process management: focuses on process execution. Linux kernel provides an application program interface that allows you to create new processes. This program also allows communication between the processes and synchronizes them. The kernel implements a unique scheduling algorithm that operates in constant time, regardless of the number of threads vying for the CPU. 

System call interface – The SCI is a thin layer that permits function calls from user space into the kernel. This interface can be dependent on architecture, even within the same processor family. 

Resource Management – It considers the number of resources used to store processes and determines where these processes are stored. The Linux kernel is also tasked with managing the system’s resources efficiently. 

The system’s resources include memory management, process, task management, and disk management. By doing so, the kernel ensures there is enough memory available for your process to run. It also guarantees the efficient working of the processor so that tasks are run and completed successfully. 

Memory Management – Linux kernel manages the computer’s memory. The memory is managed via pages. Linux kernel manages the available memory, as well as the hardware mechanisms for physical and virtual mappings. With the Linux kernel, you can swap pages that is move pages out of the memory to the disk.

What makes the Linux Kernel Standout from other Classic Unix Kernels?

There are unique features that distinguish the Linux kernel from the other Classic Unix kernels. These unique features are listed below.

The Linux Kernel Is Monolithic

The Linux kernel is a type of monolithic kernel; hence, it has a large footprint. The Linux kernel also includes system server calls, device drivers, and the file management system.

All of these make the Linux kernel better at multitasking and accessing hardware since there is direct access to any information required from memory or any running process.

You would expect that it would have the usual problems since it has a large footprint, but no. The developers of the Linux kernel have sidestepped this problem by making use of kernel modules. These Kernel modules can be loaded or unloaded at runtime, which allows you to add or remove features at any time. 

Portability – The Linux kernel is portable. It is the kernel of choice in almost all the fast supercomputers.  

Patching
Some versions of Linux kernel support direct patching. This update was applied to the Linux kernel version 4.0 released in April 2015. Updates can be applied to the kernel or even replaced without you needing to reboot your computer. Patching gives room for system updates with no downtime on systems. System updates can be especially useful in server systems. 

The Linux kernel is unable to differentiate between threads and normal processes
It does not differentiate between threads and normal processes and threads. For the Linux kernel, all processes are the same— some happen to share resources. In Linux, both Process creation and Thread creation make use of the clone system call. Linux kernel has solid support for threads, which means separate data structures are used within the kernel to depict the Thread and a process.

Linux kernel can be pre-emptive – quite different from other Unix types; the Linux kernel is capable of pre-empting a task while it is being executed in the kernel. 

Added hardware functionality – by including kennel modules that run server processes, like low-level virtualization, the Linux kennel is a step up. It can allow you to replace the entire kernel without having to reboot your computer in some instances.

What are the Components of Linux Kernel?

At the top layer is the user/application space responsible for executing user applications. Below the user space, you’ll find the kernel space; this is where the Linux kernel is found. You will also find the GNU C Library, which is responsible for providing the system call interface.

The system call interface is connected to the kernel and provides a way to facilitate the switch between the user-space application and the kernel. This interface is essential, seeing as kernel and user applications are contained in different address spaces. The kernel occupies a single address space; on the other hand, the user-space process each occupies different address spaces.

The Linux kernel is further categorized into three sub levels. The top houses the system call interface, responsible for carrying out tasks like read and write. The kernel code lies below the system call interface. The kernel code is independent of the Linux architecture. The kernel code is one of the common features of Linux supported processor architectures.

The architecture-dependent code is below the kernel code. It makes up what is commonly referred to as a BSP (Board Support Package). The architecture-dependent code acts like the processor and platform-specific code for the given architecture.

Why Should Install the Updated Linux Kernel on My Computer System?

Linux kernel updates always come with improved or new features, as well as increased driver support. Because these updates tackle previously discovered bugs and glitches, it is important you’re your Linux kernel is up to date. There are two primary ways you can install the updated Linux 5.8 kernel, which we will outline in this article.

How Can I Linux 5.8 Kernel on Ubuntu?

  • Step 1: Start by ensuring all the existing packages on your device are up to date. For this, enter the command code Sudo apt update
  • Step 2: Open a command terminal. If you are using the CLI version, the command terminal is already open. For other versions, hold down key Ctrl+Alt+T or open the command terminal from Applications.
  • Step 3: you can check the version of the Linux kernel you are running on using the command uname -sr.
  • Step 4: download the kernel package. Go to http://kernel.ubuntu.com/~kernel-ppa/mainline/ on your browser. It will bring up the versions. Select version 5.8 and then download the packages.

Step 5: Install the downloaded packages using a package manager if you have one. Or run the command: sudo dpkg -i linux-*.deb. The installation requires time. Once done, reboot your system and check if version 5.8 has been installed. Use command code uname -sr.

How to Install Linux Kernel Using Source Code

  • Step 1: Download the source package from https://www.kernel.org/ and extract it to the home partition.
  • Step 2: Next, run command code make menuconfigNext, run code sudo make modules_install install.
  • Step 3: Reboot your system.

 Conclusion

Linux Kernel acts as a communication bridge between the user applications and the installed hardware. There are different types of kernels, each with their unique properties. The Linux kernel is a monolithic kernel, which means it handles most of the Operating System’s work by itself. This article has all the information that will help you to understand the Linux kernel fully.

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