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 the operation of JK flip flop when all inputs are 0, Write the trut...

Write the truth table for a clocked J-K flip-flop that is triggered by the positive-going edge of the clock signal. Explain the operation of this flip-flop for the following condit

Proof by contradiction - artificial intelligence, Proof by Contradiction - ...

Proof by Contradiction - Artificial intelligence So, both backward chaining andforward chaining have drawbacks. Another approach is to think regarding proving theorems by contr

What is EDO RAM, What is EDO RAM A minor modification to the structure ...

What is EDO RAM A minor modification to the structure of the DRAM changes the device into an EDO (extended data output) DRAM device. In EDO memory, any memory access, including

Keyboard status word generator, Q.  Write short note on Interfacing Keyboar...

Q.  Write short note on Interfacing Keyboard, giving block diagram. Why do we need to introduce circuitry called Keyboard Status Word Generator?

What is locking, What is Locking? When two users at the same time atte...

What is Locking? When two users at the same time attempt to access the similar data record, this is synchronized by a lock mechanism

What is a cgi bin directory, A CGI bin directory is a special directory on ...

A CGI bin directory is a special directory on the server where CGI scripts are allowed to be implemented. Most servers are configured to only permit CGI scripts to be implemented f

Manipulating logical expressions, Digital circuits also manipulate logicale...

Digital circuits also manipulate logicalexpressione.g. IF account is in credit THEN allow phoneto make calls.So a digital circuit must determine if somethingis TRUE or FALSE. Norma

Explain about two-pass assembler, Q. Explain about Two-pass assembler? ...

Q. Explain about Two-pass assembler? Assemblers usually make two or more passes through a source program in order to resolve forward references in a program. A forward referenc

Define the while loop, The while Loop The while loop repeats a statemen...

The while Loop The while loop repeats a statement until the test at the top proves false. As an example, here is a function to return the length of a string. int string_leng

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