What is the Linux kernel and what tasks does it perform?

The Linux kernel is the main component of the Linux operating system, a low-level program that serves as an interface between the computer hardware and user applications.

The main tasks of the Linux kernel include:

• Process management: Distributing CPU time among processes, creating, terminating, and context switching processes.
• Memory management: Allocating, freeing, and protecting memory for processes, managing virtual memory and swapping.
• Device management: Providing interfaces for accessing hardware devices (hard drives, network cards, etc.) through drivers.

// Example kernel function for memory allocation
void *kmalloc(size_t size, gfp_t flags);

• File system management: Organizing and accessing data on storage media, supporting various file systems (ext4, XFS, etc.).
• Network functions: Handling network packets, implementing network protocols (TCP/IP), and managing network interfaces.
• System calls: Providing a standardized set of functions for user programs to interact with the kernel.

# Example of using the open system call via strace
strace cat /etc/fstab

• Security management: Implementing access control mechanisms, process isolation, and privilege management.

The kernel operates in privileged mode (kernel space), having direct access to hardware, while user applications run in user mode (user space), interacting with the kernel through system calls.

Here is a simple table summarizing the interaction:

Mode	Hardware Access	Examples
Kernel Space	Direct	Kernel
User Space	Through system calls	Applications