Kernel | Operating System

PPT on Kernel of an Operating System.

1. KERNEL OF OPERATING SYSTEM By - Kanan, Kirti & Sumit

2. 1. OS Architecture 2. OS & Kernel as a Window 3. What is Kernel 4. Diagrams Explanation 5. Responsibilities of Kernel 6. Kernel Mode vs User Mode 7. Necessity of Dual Mode GLOSSARY

3. After this presentation, we will be able to answer the following questions - 1. Why OS & Kernel act as a Window to the User ? 2. How OS Architecture looks ? 3. What is Kernel ? 4. What are the responsibilities of Kernel ? 5. How to differentiate between Kernel Mode & User Mode ? 6. What is the necessity of Dual Mode in OS ? OBJECTIVE

4. Window OS User Kernel Devices Hardware Software

5. OS   A rchitecture   1 2 3

6. K   E  R  N  E  L     Kernel  is  the  core  component  of  Operating  System  where  actual  code  and  functionality of  OS  lies. It  is  responsible  for  scheduling  running  of  user  and  other  processes. It  is  responsible  for  allocating   memory.

7. Responsibilities of KERNEL Device Management :   A system has many devices connected to it like CPU, a memory device, sound cards, graphic cards, etc. A kernel stores all the data related to all the devices in the device driver ( without this kernel won't be able to control the devices ). Thus kernel knows what a device can do and how to manipulate it to bring out the best performance. It also manages communication between all the devices. The kernel has certain rules that have to be followed by all the devices. Handling system calls : Handling system calls means a programmer can write a query or ask the kernel to perform a task.

8. Responsibilities of KERNEL Memory management :   Another function that kernel has to manage is the memory management. The kernel keeps track of used and unused memory and makes sure that processes shouldn't manipulate data of each other using virtual memory addresses. Process management :   In the process management, kernel assigns enough time and gives priorities to processes before handling CPU to other processes. It also deals with security and ownership information.

9. In Kernel Mode The system starts in kernel mode when it boots and after the operating system is loaded, it executes applications in user mode. There are some privileged instructions that can only be executed in kernel mode. These are interrupt instructions, input output management etc. If the privileged instructions are executed in user mode, it is illegal and a trap is generated. The mode bit is set to 0 in the kernel mode. It is changed from 0 to 1 when switching from kernel mode to user mode. KERNEL    MODE   Vs    USER   mode

10. KERNEL    MODE   Vs    USER   mode In User Mode The system is in user mode when the operating system is running a user application such as handling a text editor. The transition from user mode to kernel mode occurs when the application requests the help of operating system or an interrupt or a system call occurs. The mode bit is set to 1 in the user mode. It is changed from 1 to 0 when switching from user mode to kernel mode.

11. KERNEL    MODE   Vs    USER   mode Kernel  mode  is  used  to  perform  lower  level  functionalities &  in  user  mode,  the  code  has  no  access  to  hardware  or  lower  level resources  like memory. The  kernel  (which  is  the  core  of  the  OS  and  has  complete   control   over  everything   that   occurs in   the   system)   is   trusted   software. User  Mode,  A  non-privileged   mode   for   user   programs,  that   is,  for  everything  other  than  the kernel.

12. Necessity of Dual Mode in Operating System The lack of a dual mode i.e. user mode and kernel mode in an operating system can cause serious problems. Some of these are − A running user program can accidentally wipe out the operating system by overwriting it with user data. Multiple processes can write in the same system at the same time, with disastrous results. These problems could have occurred in the MS-DOS operating system which had no mode bit and so no dual mode.

13. CONCLUSION K ernel is heart of operating system. To be sure, the kernel has unique qualities. It enforces its own rules and stakes. T here are various responsibilities of kernel like managing devices, Handling system call , managing memory and different process also. Both the modes are very important for OS and are dependent on each other.