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

Perfect induction, Any identity or equality in Boolean algebra, suchas de M...

Any identity or equality in Boolean algebra, suchas de Morgan's Theorem can be proved usingthe method of perfect induction. 1. All combinations of variables are written down.

What is a resource-allocation graph, What is a resource-allocation graph? ...

What is a resource-allocation graph? Deadlocks can be described more precisely in terms of a directed graph known as a system resource allocation graph. This graph having of a

Prove, state and prove distributive law?

state and prove distributive law?

What do you mean by single construct in fortan, Q. What do you mean by Sing...

Q. What do you mean by Single Construct in FORTAN? Single construct specifies the associated structured block is executed by just one thread in team (not essentially the master

What is the advantage of caching in a web browser, What is the advantage of...

What is the advantage of caching in a web browser? Like other application browsers utilize a cache to enhance document access. The browser places a copy of all items it retriev

Explain difference between scanning and parsing, Explain difference between...

Explain difference between Scanning and parsing. Scanning and parsing: Scanning process is the process of recognizing the lexical components in a source string whereas parsin

Determine the begin - end keywords, Determine the begin - end keywords ...

Determine the begin - end keywords Group several statements together. Cause the statements to be evaluated sequentially (one at a time) -> Any timing within sequential group

Describe arp message format in brief, Describe ARP message format in brief....

Describe ARP message format in brief.                             0                                        8                                      16

State the advantages of CMOS, State the advantages of CMOS. Ans. Su...

State the advantages of CMOS. Ans. Subsequent are the advantages of CMOS: Both n-channel and p-channel devices are fabricated on similar substrate. Low power di

Programming for arithmetic and string operations, Advanced aspects of assem...

Advanced aspects of assembly language programming in this section. A number of these aspects give assembly an edge over high level language programming as far as efficiency is conc

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