Kernel build. Kernel build is the process of compiling and configuring the Linux kernel source code to generate a functional kernel image that can be loaded into memory and executed by the operating system. The kernel serves as the core component of the Linux operating system, providing essential functions such as process management, memory management, device drivers, and system calls.

Overview 
The Linux kernel is an open-source software project maintained by a global community of developers. It is distributed under the terms of the GNU General Public License (GPL) and is available for various architectures, including x86, ARM, MIPS, and others. While precompiled kernel images are often provided by Linux distributions, users and system administrators may choose to customize and build their own kernels to suit specific requirements or hardware configurations.

Process 
The process of building a Linux kernel involves several steps:

 Obtaining the Source Code: The first step is to obtain the kernel source code. This can be done by downloading a tarball from kernel.org or by using version control systems like Git to clone the source repository.
 Configuration: Before compiling the kernel, it needs to be configured. This involves selecting the desired features, options, and device drivers that will be included in the kernel image. Configuration can be done manually through the make menuconfig, make xconfig, or make config commands, or by using pre-existing configuration files.
 Compilation: Once the kernel is configured, it can be compiled using the make command. The compilation process translates the source code into executable machine code specific to the target architecture. This step may take some time, depending on the speed of the system and the complexity of the configuration.
 Installation: After successful compilation, the newly built kernel image, along with associated files such as kernel modules and firmware, needs to be installed in the appropriate location on the system. This typically involves copying the kernel image to the /boot directory and updating the bootloader configuration to recognize the new kernel.
 Testing and Deployment: Before deploying the new kernel in a production environment, it is essential to test it thoroughly to ensure compatibility with hardware and software components. This may involve booting into the new kernel, running various applications, and performing system stability tests. Once validated, the new kernel can be deployed to production systems.

Importance 
Custom kernel builds offer several advantages:

 Performance Optimization: By including only necessary features and device drivers, custom kernels can be optimized for specific hardware configurations, resulting in improved performance and efficiency.
 Feature Customization: Users can enable or disable kernel features based on their requirements, allowing for a more tailored and streamlined system.
 Security: Building a custom kernel enables users to apply security patches and updates promptly, reducing the risk of security vulnerabilities.
 Learning and Experimentation: Kernel building provides an opportunity for users to learn about the inner workings of the Linux kernel and experiment with different configurations and optimizations.

References

Further reading

External links 
How to build a custom Linux kernel from scratch.

Linux kernel