Lecture 7 -- Kernel & System

Kernel

the core component of the operating system that manages hardware, memory, processes and file system access

Kernel space

A memory region where the kernel runs with full access to hardware and system resources

User space

memory region where applications and user processes run with limited access

System calls

requests made by user space programs to the kernel to perform operations

Kernel vs OS

• kernel = core component

• operating system = kernel + user applications + utilities

Monolithic kernel

a kernel where all system services run in kernel space

Microkernel

a kernel where only essential services run in kernel space and others run in user space

Linux kernel

a free and open source monolithic kernel used in Linux operating systems

uname

displays system and kernel information

uname -r

displays the current kernel version

Kernel modules

loadable components that extend kernel functionality without rebooting

modprobe

loads or removes kernel modules and automatically handles dependencies

lsmod

lists all currently loaded kernel modules

insmod

loads a kernel module manually (does NOT handle dependencies)

rmmod

removes a kernel module

depmod

creates and updates module dependency information

Kernel module config

location /etc/modprobe.d/ used to configure module behaviour

Kernel parameters

settings that control kernel behaviour at runtime

sysctl command

used to view and modify kernel parameters

/proc file system

a virtual file system that provides real-time system and kernel information

dmesg

displays messages from the kernel buffer, used for troubleshooting and checking hardware/events

kernel space vs user space

• kernel space has full hardware access

• user space must request access via system calls

monolithic vs microkernel

• monolithic = faster, less stable

• microkernel = more stable, slower performance