Configuration guide for building Linux kernel modules using CMake

Configuration Guide for Using CMake to Build Linux Kernel Modules

Introduction:
CMake is a cross-platform build tool that can help developers manage and build projects more conveniently. When developing Linux kernel modules, using CMake can simplify the configuration and compilation process and improve development efficiency. This article will introduce how to use CMake to configure and build Linux kernel modules, with code examples.

1. Install CMake
Before we start, we need to install CMake first. On Ubuntu, you can install it with the following command:

sudo apt-get install cmake

2. Create the CMakeLists.txt file
In the project root directory of the Linux kernel module, create a file named CMakeLists.txt. This file describes the project's build configuration and dependencies.

The following is a simple CMakeLists.txt file example:

# CMake最低版本要求
cmake_minimum_required(VERSION 3.10)

# 项目名称
project(kmodule_example)

# 内核模块源文件
set(SOURCES example_module.c)

# 编译选项
add_compile_options(-Wall -Wextra)

# 内核模块的构建配置
add_module(${PROJECT_NAME} ${SOURCES})

In this example, we first specify the minimum version requirements of CMake and name the project "kmodule_example". Next, we put the source file of the kernel module (example_module.c) in a variable. We then added some compilation options (-Wall -Wextra) to enable warnings and add additional warning information.

Finally, we use the add_module() function to define the build configuration of the kernel module. The first parameter is the name of the kernel module, and the second parameter is the source file of the kernel module.

3. Build and install the kernel module
Create a directory named build in the project root directory, and execute the following command in the build directory:

cmake ..
make

Executing the cmake command will be based on CMakeLists .txt file to generate Makefile, and then execute the make command to compile the kernel module.

After successful compilation, you can use the following command to install the kernel module:

sudo make install

The kernel module will be installed to the standard location of the system.

4. Clean up the build directory
If you need to clean up the intermediate files generated by the build, you can execute the following command:

make clean

This will delete the generated executable files and temporary files.

5. Summary
In this article, we introduced how to use CMake to configure and build Linux kernel modules. By using CMake, we can manage and build projects more conveniently and improve development efficiency. I hope this article can help you use CMake more easily when developing Linux kernel modules.

Code example:
The following is a simple Linux kernel module example named example_module.c:

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("An example Linux kernel module");

static int __init example_module_init(void)
{
    printk(KERN_INFO "Hello, World!
");
    return 0;
}

static void __exit example_module_exit(void)
{
    printk(KERN_INFO "Goodbye, World!
");
}

module_init(example_module_init);
module_exit(example_module_exit);

This example kernel module implements a simple initialization and exit function. In the initialization function, it prints a message "Hello, World!"; in the exit function, it prints a message "Goodbye, World!".

By using the CMake configuration and build methods introduced in this article, it will be very convenient to compile this sample module.

Reference link:

• CMake official documentation: https://cmake.org/documentation/
• Linux kernel module development guide: https://www. kernel.org/doc/html/latest/kbuild/modules.html

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