Tuesday, May 12, 2020

Device Management | Protection and Security | Page Fault

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Intro: Q1.What do you mean by Device Management in operating System? Q2.What is System, Protection and Security in operating System? Q3.When do Page Fault occur? Describe the steps in handling a page fault(Operating System all notes)

Device-Management-&-Protection-Security-&-Page-Fault

Q1. What do you mean by Device Management in operating System?

Ans. Device Management: Within the computer, activating and controlling the peripheral devices. In a desktop computer, the operating system interacts with the device drivers for peripheral control. In very small embedded systems, the device management routines may be included within the Operating System.
Configuring and deploying applications to the computing devices within an organization, such as desktop PCs, laptops, and mobile devices.

The Functions of Device Management:

The following functions are used in device management:
FunctionDescription
Device I/O controlSends a control code directly to a specified device driver.
Install new deviceInstalls a new device. The user is prompted to select the device.
Register device notificationRegisters the device or type of device for which a window will receive notifications.
Unregister device notificationCloses the specified device notification handle.

Q2. What is System, Protection and Security in operating System?

Ans. System: System means a set of things working together as part of a mechanism or an interconnecting network, a complex whole.
Protection: Protection is a mechanism that prevents accidental or intentional misuse of a system. Its aspects include authentication, authorization and access enforcement.
Security: Security means to limit access to only what is absolutely needed. It involves logging, the principle of minimum privilege, absence of bugs, information flow control, etc.

Q3. When do Page Fault occur? Describe the steps in handling a page fault?

Ans. Page Fault: A page fault is an exception that is raised by the memory management unit when a needed page is not mapped in physical memory. This exception is passed on to the operating system which will bring the required page into physical memory.

An interrupt that occurs when a program requests data that is not currently in real memory. The interrupt triggers the operating system to fetch the data from virtual memory and load it into RAM.

An invalid page fault or page fault error occurs when the operating system cannot find the data in virtual memory. This usually happens when the virtual memory area or the table that maps virtual addresses to real addresses becomes corrupt.

Steps in Handling a Page Fault

1. We check an internal table kept with the process control block for this process to determine if the reference was invalid or in-valid memory access. If it was invalid, we terminate the program.
2. If it was a valid reference, but we have not yet brought on that page we must now bring it in.
3. Find a free frame.
4. Schedule a disk-operation to read the desired page into the newly allocated frame.
5. When the disk read a complete, modified the internal table kept with the process and the page-table to indicate the page is now in memory.
6. Restart the instruction that was interrupted by the illegal address trap the process can now access the page as if it had always been in memory.




[ Topic= Device Management in operating System,  Protection and Security  in operating system ]



External Links:-

1. Device Management in operating System - (click here)
2. Protection and Security  in operating system - (click here)
3. When do Page Fault occur - (click here)


[ Topic= Device Management in operating System,  Protection and Security  in operating system ]
[ Topic= Device Management in operating System,  Protection and Security  in operating system ]

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