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 program invisible registers, What are program invisible registe...

What are program invisible registers? Global and local descriptor tables are found in memory system. In order to specify and access the address of these tables, program invisi

Explain network security, Explain network security. Network security me...

Explain network security. Network security means the security of networks and their services from unauthorized access, changes, destruction or disclosure. It gives for assuranc

Why does microprocessor contain rom chips?, Microprocessor have ROM chip be...

Microprocessor have ROM chip because it have instructions to implement data. It have the monitor program which not only include implementation instruction but also interfacing

Variance of predictions is expected to decrease, Suppose the random sample ...

Suppose the random sample used for each tree in the previous random forest is decreased from 1000 rows to 500 rows. Circle ALL that are true for the ensemble classifier. a) Vari

Returns the information about tasks running, Returns the information about ...

Returns the information about tasks running int info = pvm_tasks( int where, int *ntask, struct pvmtaskinfo **taskp ) struct pvmtaskinfo {  int ti_tid; int ti_pt

What is meant by latch, Latch is a D- type flip-flop used as a temporary st...

Latch is a D- type flip-flop used as a temporary storage device controlled by a timing signal, which can kept 0 or 1. The primary function of a Latch is data storage. It is used in

.image forgery detection, what is the code to detect image forgery using Ma...

what is the code to detect image forgery using Matlab..??

Dpsd -asynchronous circuits, an asyncronous sequential circuit is described...

an asyncronous sequential circuit is described by the the exitatio function and the output function y=x1x2''+(x1=x2'')y output function z=y a)draw the logic diagram of the circuit.

Define memory allocation scheme in ''external'' fragmentation, The memory a...

The memory allocation scheme subject to “external” fragmentation is? Segmentation is the memory allocation scheme subject to “external” fragmentation.

How many bits are required for a ladder d/a converter, How many bits are re...

How many bits are required at the input of a ladder D/A converter, if it is required to give a resolution of 5mV and if the full scale output is +5V. Find the %age resolution.

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