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

Explain sequential sharing, Explain Sequential Sharing In this sharing ...

Explain Sequential Sharing In this sharing method, a file can be shared by just one program at a time, i.e. file accesses by P1 and P2 are spaced out over time. A lock field ca

Real life decoding, We have not considered the time element in our decoding...

We have not considered the time element in our decoding. An important time for decoding is the time from the address strobe (AS) to when the data is required in a read.   Time

Conversion of decimal number 10.625 into binary number, Conversion of decim...

Conversion of decimal number 10.625 into binary number ? Ans. There is integer part is 10 and fractional part is 0.625. Firstly convert the decimal number 10 in its equal bina

Explain the test instruction, Explain the TEST instruction TEST instru...

Explain the TEST instruction TEST instruction performs the AND operation. The difference is that AND instruction changes the destination operand whereas TEST instruction doesn

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,

How steps of instruction execution can be broken down, Q. How steps of inst...

Q. How steps of instruction execution can be broken down? Let's explain how these steps of instruction execution can be broken down to micro-operations. To make easier this dis

The height of the left sub tree and height of the right tree, The differenc...

The difference among the height of the left sub tree and height of the right tree, for each node, is almost one.  AVL - tree

What is synchronous message passing, Q. What is Synchronous message passing...

Q. What is Synchronous message passing? In Synchronous message passing is executed on synchronous communication network.  In that case sender and receiver processes should be

Problem specification - logic programs, Problem Specification : Hence ...

Problem Specification : Hence given the above context for "ILP" there we can state the learning problem as follows: that we are given a set of positive and a set of negative e

Illustrate domain names and address resolution, Q. Illustrate Domain Names ...

Q. Illustrate Domain Names and Address Resolution? But what if you don't know IP address of the computer you want to connect to? What happens if you need to access a web server

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