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

Telematics, How are switching system classified

How are switching system classified

Designing e-cash based system, How can it be achieved in designing e-cash b...

How can it be achieved in designing e-cash based system? E-cash is essentially an online solution.  The buyer must validate the coins by the issuer in order to get the purchase

What is optical mark recognition, Optical mark recognition (OMR)  OMR ...

Optical mark recognition (OMR)  OMR technology scans a printed form and reads pre-defined positions (where specific fields have been filled in for instance ?-?or _); system re

Determine about the verilog task, Determine about the Verilog Task - Ta...

Determine about the Verilog Task - Tasks are capable of enabling a function as well as enabling other versions of a Task. - Tasks also run with a zero simulation however the

What are advantages and drawbacks of latches, What are advantages and drawb...

What are advantages and drawbacks of latches? Advantages and drawbacks of latches: Area of a latch is classically less than a Flip Flop. It consumes less power, becaus

Write an applet, Write an applet that can interact with both the HTTP clien...

Write an applet that can interact with both the HTTP client and HTML interpreter in a browser.  import java.applet.*; import java.net.*;                        // import pac

What is a microinstruction, What is a microinstruction? Each word in co...

What is a microinstruction? Each word in control memory having within it a microinstruction.  The microinstruction specifies one or more micro-operations for the system.  A seq

What is virtual memeory, What is virtual memory? How address mapping is don...

What is virtual memory? How address mapping is done in cache memory? Elaborate your answer with examples.

Describe about directory in doc, Q. Describe about directory in DOC? We...

Q. Describe about directory in DOC? We all know that, the volume of the hard disk is generally quite large (10 MB to a few GB). You can keep hundreds or even thousands of files

Detrmine pure paging, Which is not a key piece of information, stored in si...

Which is not a key piece of information, stored in single page table entry, assuming pure paging and virtual memory Ans. A reference for the disk block which stores the page is

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