Implementing protection with virtual memory, Computer Engineering

Assignment Help:

Implementing Protection with Virtual Memory - computer architecture:

To enable the operating system to implement protection in the VM system, the HW have to:

I. Support at least 2 modes that denoted whether the running process is a user process (executive process) or an operating system process (kernel/supervisor process).

II. Provide a part ion of the CPU state that a user process may read but not write (includes supervisor mode bit).

  • Provide mechanism where the CPU may go from user mode to supervisor mode (accomplished by a system call exception) and vice versa (return from exception instruction).

o   Only operating system process may change page tables. Page tables are held in operating system address space thereby preventing a user procedure from changing them. 

o   When processes desire to share information in a restricted way, the OS have to assist them.

o   The write access bit (in both the TLB and the page table) can be used to limit the sharing to only read sharing.

 


Related Discussions:- Implementing protection with virtual memory

Describe about the protection features present in ms access, If a programme...

If a programmer doesn't wish to make modifies to the document he can lock the document data and its code from more changes by changing the extension of the file system to .MDE. Cha

Explain Not recently used page replacement algorithm, Not Recently Used Pag...

Not Recently Used Page Replacement Algorithm The not recently used abbreviated as NRU page replacement algorithm works on the subsequent principle: while a page is referenced,

Explain significance of init() & destroy( ) method of applet, Explain the s...

Explain the significance of init() and destroy( ) methods of an applet? Also explain two ways of invoking an applet. The init( ) method is utilized for fundamental initializati

# real life business subsystem, Is production, marketing, personal, materia...

Is production, marketing, personal, material, finance are the real life business subsystems? if yes, then how?

Is it possible to create graph form spreadsheets, Is it possible to create ...

Is it possible to create graph form spreadsheets For example IF G5 > 100 THEN "Y" ELSE "N" -  It's also possible to create graphs and charts from spreadsheets (such as using

. net is compile time or runtime environment, . NET is Compile Time OR RunT...

. NET is Compile Time OR RunTime Environment?   .Net's framework has CLS,CTS and CLR.CTS checks declaration of types at the time when u write code and CLS explains some rules a

Evidence of intelligent behavior - artificial intelligence, Evidence of int...

Evidence of intelligent behavior - Artificial Intelligence: Machines mean they could simply be personal computers, or they could be robots with embedded automative systems, or

Instruction pipeline-level of processing, Classification according to level...

Classification according to level of processing According to this classification, computer operations are classified as arithmetic operations and instruction implementation. Ne

Define multi programming, Define multi programming? Many operating syst...

Define multi programming? Many operating systems are designed to enable the cpu to process a number of independent programs concurrently. This concept is  known as multi progra

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd