Kernel Modules and Their Lifecycle
Kernel modules are pieces of code that can be loaded into or removed from the kernel at runtime, without the need to reboot the system. They are used to extend the functionality of the kernel, such as adding support for new hardware, filesystems, or other features, without modifying the core kernel itself. This modular approach makes it easier to maintain and update the kernel, as you can add or remove features as needed.
simple_module.c
123456789101112131415161718192021#include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> static int __init simple_init(void) { printk(KERN_INFO "Simple Module: Init called\n"); return 0; } static void __exit simple_exit(void) { printk(KERN_INFO "Simple Module: Exit called\n"); } module_init(simple_init); module_exit(simple_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Your Name"); MODULE_DESCRIPTION("A simple kernel module example");
The lifecycle of a kernel module is controlled by its initialization and exit functions. When you load a module into the kernel, the function specified with the module_init macro is called. This is where you typically allocate resources, register devices, or perform setup tasks. When the module is removed, the function specified with the module_exit macro is called, which is where you should clean up and release any resources acquired during initialization. In the example above, simple_init is the initialization function, and simple_exit is the cleanup function. This structure ensures that modules can be safely loaded and unloaded without affecting the stability of the kernel.
dependency_module.c
123456#include <linux/module.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("Your Name"); MODULE_DESCRIPTION("Module with dependency example"); MODULE_DEPEND(dep_module, "other_module", "1.0", "2.0", "2.5");
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Kernel Modules and Their Lifecycle
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Kernel modules are pieces of code that can be loaded into or removed from the kernel at runtime, without the need to reboot the system. They are used to extend the functionality of the kernel, such as adding support for new hardware, filesystems, or other features, without modifying the core kernel itself. This modular approach makes it easier to maintain and update the kernel, as you can add or remove features as needed.
simple_module.c
123456789101112131415161718192021#include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> static int __init simple_init(void) { printk(KERN_INFO "Simple Module: Init called\n"); return 0; } static void __exit simple_exit(void) { printk(KERN_INFO "Simple Module: Exit called\n"); } module_init(simple_init); module_exit(simple_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Your Name"); MODULE_DESCRIPTION("A simple kernel module example");
The lifecycle of a kernel module is controlled by its initialization and exit functions. When you load a module into the kernel, the function specified with the module_init macro is called. This is where you typically allocate resources, register devices, or perform setup tasks. When the module is removed, the function specified with the module_exit macro is called, which is where you should clean up and release any resources acquired during initialization. In the example above, simple_init is the initialization function, and simple_exit is the cleanup function. This structure ensures that modules can be safely loaded and unloaded without affecting the stability of the kernel.
dependency_module.c
123456#include <linux/module.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("Your Name"); MODULE_DESCRIPTION("Module with dependency example"); MODULE_DEPEND(dep_module, "other_module", "1.0", "2.0", "2.5");
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