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8/8/2019 Linux and Kernel Component
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Presented by:
Raheel Ahmed Memon
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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..