linux and kernel component

8/8/2019 Linux and Kernel Component

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Presented by:

Raheel Ahmed Memon

[email protected]


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What is Linux


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Properties of Linux

Multiprocessor:

Multiprocessor means that Several processes can be handled

concurrently by different CPUs.One of the few operating systems supporting multiprocessor.

Multiuser:

Support separate user accounts with different levels of accessprivilege

Each user can work concurrently in one system

Giving each user the experience of being connected to a

standalone computer


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Properties of linux

Multiplatform:

Linux was Originally developed only for the personal

computer (Intel 80386)

But it runs on more than ten processor architectures today

Supported platforms extends from small digital personalassistants over the standard personal computer

Multitasking:

Multitasking is an operating-system technique for sharinga single processor among multiple threads of execution.


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Properties of Linux

Efficient Network Implementation:

The Linux kernel makes available a well structured implementation of the networkfunctionality.

Open Source:

The source code is available to anyone who wants it, and can be freely modified,developed, and so forth.

Linux is Free:

free of charge

freedom to use Linux

free Software applications, programming

Advance in Technology:

Linux kernel provides a stable and relatively complete implementation of the newInternet Protocol IPv6.


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Linux Kernel Structure


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Linux Conceptual Architecture

User Space

Linux Kernel Hardware

User Space

Linux Kernel

Hardware


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Kernel Architecture

Structure of Linux Kernel

Process management

Memory management

File System

Device Drivers

Network


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Components

Process Management:

Responsible for creating and terminating processes

Memory Management:

Responsible for allowing each process its own memory section

File System:

Responsible for handling over the file system interface

Device Drivers:

This is abstract from underlying hardware, it allow you to accessthis hardware

Network:

All network operations have to be managed by the operatingsystem


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Monolithic Architecture and

Microkernels

Linux OS is based on monolithic kernel

Windows NT is microkernel architecture


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Key Concept

Monolithic:

Is a kernel architecture where the entire operating

system is working in the kernel space and aloneas supervisor mode.

Monolithic kernel examples

Unix kernels Linux

Mac OS kernel, up to Mac OS 8.6

DOS


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Key Concept

Microkernel:

Only parts which really require to be in a privileged

mode are in kernel space. the remaining functionalityof the OS is moved to independent processes orthreads, running outside the OS kernel. They use adefined interface to communicate with the

microkernel, generally via system callsExamples:

Windows NT

Chorus MLinux


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System Calls

The system call interface layer contains entry point in thekernel code user process must not be given open access tothe kernel code for security reasons.

However when a process want to access or use afunctionality of of the OS kernel, it has to use a system callto do this. The system call use the process to change thesystem mode

User

Kernel

Hardware

System Call


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System Call Execution

This sequence ofevents takes placewhen a process

invokes a system call


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Hardware Interrupts

Peripherals use hardware interrupts (oftenabbreviated as HW IRQs) to inform an operating

system about important eventsExample:

That the mouse has been moved, a key has been

pressed

Registered at runtime by using the function request_irq( )

To release the handling routine of an interrupt free_irq( )


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Software Interrupts

Software interrupts (or soft IRQs for short) areactually a form of activity that can be scheduled

for later execution rather than real interrupts.

Software and hardware interrupts differ mainly in

that; a software interrupt is scheduled forexecution by an activity of the kernel and has towait until it is called by the scheduler.

started by the function do_softirq()


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..Thanks..

linux and kernel component

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