Kernel build

Last updated April 27, 2024

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.^[1] 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.^[2]

Overview

The Linux kernel is an open-source software project maintained by a global community of developers.^[3] 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.^[4]

Process

The process of building a Linux kernel involves several steps:^[5]^[4]

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.

Related Research Articles

The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and works for many programming languages, including Ada, Assembly, C, C++, D, Fortran, Haskell, Go, Objective-C, OpenCL C, Modula-2, Pascal, Rust, and partially others.

A Linux distribution is an operating system made from a software collection that includes the Linux kernel and often a package management system. Linux users usually obtain their operating system by downloading one of the Linux distributions, which are available for a wide variety of systems ranging from embedded devices and personal computers to powerful supercomputers.

GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Free Software Foundation's Multiboot Specification, which provides a user the choice to boot one of multiple operating systems installed on a computer or select a specific kernel configuration available on a particular operating system's partitions.

A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on Android devices is a cross compiler.

udev is a device manager for the Linux kernel. As the successor of devfsd and hotplug, udev primarily manages device nodes in the /dev directory. At the same time, udev also handles all user space events raised when hardware devices are added into the system or removed from it, including firmware loading as required by certain devices.

make menuconfig is one of five similar tools that can configure Linux source, a necessary early step needed to compile the source code. make menuconfig, with a menu-driven user interface, allows the user to choose the features of Linux that will be compiled. It is normally invoked using the command make menuconfig; menuconfig is a target in Linux Makefile.

The MicroBlaze is a soft microprocessor core designed for Xilinx field-programmable gate arrays (FPGA). As a soft-core processor, MicroBlaze is implemented entirely in the general-purpose memory and logic fabric of Xilinx FPGAs.

In Linux systems, initrd is a scheme for loading a temporary root file system into memory, to be used as part of the Linux startup process. initrd and initramfs refer to two different methods of achieving this. Both are commonly used to make preparations before the real root file system can be mounted.

In the context of free and open-source software, proprietary software only available as a binary executable is referred to as a blob or binary blob. The term usually refers to a device driver module loaded into the kernel of an open-source operating system, and is sometimes also applied to code running outside the kernel, such as system firmware images, microcode updates, or userland programs. The term blob was first used in database management systems to describe a collection of binary data stored as a single entity.

<span class="mw-page-title-main">Linux</span> Family of Unix-like operating systems

Linux is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution (distro), which includes the kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses and recommends the name "GNU/Linux" to emphasize the use and importance of GNU software in many distributions, causing some controversy.

The Linux booting process involves multiple stages and is in many ways similar to the BSD and other Unix-style boot processes, from which it derives. Although the Linux booting process depends very much on the computer architecture, those architectures share similar stages and software components, including system startup, bootloader execution, loading and startup of a Linux kernel image, and execution of various startup scripts and daemons. Those are grouped into 4 steps: system startup, bootloader stage, kernel stage, and init process. When a Linux system is powered up or reset, its processor will execute a specific firmware/program for system initialization, such as Power-on self-test, invoking the reset vector to start a program at a known address in flash/ROM, then load the bootloader into RAM for later execution. In personal computer (PC), not only limited to Linux-distro PC, this firmware/program is called BIOS, which is stored in the mainboard. In embedded Linux system, this firmware/program is called boot ROM. After being loaded into RAM, bootloader will execute to load the second-stage bootloader. The second-stage bootloader will load the kernel image into memory, decompress and initialize it then pass control to this kernel image. Second-stage bootloader also performs several operation on the system such as system hardware check, mounting the root device, loading the necessary kernel modules, etc. Finally, the very first user-space process starts, and other high-level system initializations are performed.

ELinOS is a commercial development environment for embedded Linux. It consists of a Linux distribution for the target embedded system and development tools for a development host computer. The development host computer usually is a standard desktop computer running Linux or Windows. The Linux system and the application software for the target device are both created on the development host.

A standard operating environment (SOE) is a standard implementation of an operating system and its associated software. Associated names and concepts include:

<span class="mw-page-title-main">Linux kernel</span> Operating system kernel

The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally written in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix.

<span class="mw-page-title-main">Linux-libre</span> Version of the Linux kernel without proprietary code

According to the Free Software Foundation Latin America, Linux-libre is a modified version of the Linux kernel that contains no binary blobs, obfuscated code, or code released under proprietary licenses. In the Linux kernel, they are mostly used for proprietary firmware images. While generally redistributable, binary blobs do not give the user the freedom to audit, modify, or, consequently, redistribute their modified versions. The GNU Project keeps Linux-libre in synchronization with the mainline Linux kernel.

NixOS is a free and open source Linux distribution based on the Nix package manager. NixOS uses an immutable design and an atomic update model. Its use of a declarative configuration system allows reproducibility and portability.

OpenWrt is an open-source project for embedded operating systems based on Linux, primarily used on embedded devices to route network traffic. The main components are Linux, util-linux, musl, and BusyBox. All components have been optimized to be small enough to fit into the limited storage and memory available in home routers.

<span class="mw-page-title-main">Parabola GNU/Linux-libre</span> Linux distribution based on Arch Linux offering only free software

Parabola GNU/Linux-libre is a free and open-source Linux distribution based on Arch Linux and Arch Linux ARM for the x86-64, i686, and ARMv7 architectures. It is distinguished from other Arch-based distributions by offering only free software. It includes the GNU operating system components common to many Linux distributions and the Linux-libre kernel instead of the generic Linux kernel. Parabola is listed by the Free Software Foundation as a completely free operating system, true to their Free System Distribution Guidelines.

Buildroot is a set of Makefiles and patches that simplifies and automates the process of building a complete and bootable Linux environment for an embedded system, while using cross-compilation to allow building for multiple target platforms on a single Linux-based development system. Buildroot can automatically build the required cross-compilation toolchain, create a root file system, compile a Linux kernel image, and generate a boot loader for the targeted embedded system, or it can perform any independent combination of these steps. For example, an already installed cross-compilation toolchain can be used independently, while Buildroot only creates the root file system.

Windows Subsystem for Linux (WSL) is a feature of Microsoft Windows that allows developers to run a Linux environment without the need for a separate virtual machine or dual booting. There are two versions of WSL: WSL 1 and WSL 2. WSL is not available to all Windows 10 users by default. It can be installed either by joining the Windows Insider program or manually via Microsoft Store or Winget.

References

↑ "Kernel overview". Android Open Source Project. Retrieved 2024-03-22.
↑ Bovet, Daniel P.; Cesati, Marco (2005-11-17). Understanding the Linux Kernel: From I/O Ports to Process Management. "O'Reilly Media, Inc.". ISBN 978-0-596-55491-0.
↑ "Linux and GNU - GNU Project - Free Software Foundation". www.gnu.org. Retrieved 2024-03-22.
1 2 Soyinka, Wale. "Building and Installing Custom Linux Kernels - Documentation". docs.rockylinux.org. Retrieved 2024-03-22.
↑ "Kernel Build System — The Linux Kernel documentation". docs.kernel.org. Retrieved 2024-03-22.

External links

How to build a custom Linux kernel from scratch.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[1] "Kernel overview". Android Open Source Project. Retrieved 2024-03-22.

[2] Bovet, Daniel P.; Cesati, Marco (2005-11-17). Understanding the Linux Kernel: From I/O Ports to Process Management. "O'Reilly Media, Inc.". ISBN 978-0-596-55491-0.

[3] "Linux and GNU - GNU Project - Free Software Foundation". www.gnu.org. Retrieved 2024-03-22.

[rocky-4] 1 2 Soyinka, Wale. "Building and Installing Custom Linux Kernels - Documentation". docs.rockylinux.org. Retrieved 2024-03-22.

[5] "Kernel Build System — The Linux Kernel documentation". docs.kernel.org. Retrieved 2024-03-22.

[1]

[2]

[3]

[4]

[5]