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 pre-emptive scheduling, Explain Pre-emptive scheduling? Pre-em...

Explain Pre-emptive scheduling? Pre-emptive scheduling: in its approach, center processing unit can be taken away from a process if there is a require while in a non-pre-empt

Array is a pointer to pointer to int, Array is a pointer-to-pointer-to-int:...

Array is a pointer-to-pointer-to-int: at the first level, it points to a block of pointers, one for each row. That first-level pointer is the first one we allocate; it has nrows e

Sigmoid units-artificial intelligence, Sigmoid units - Artificial intellige...

Sigmoid units - Artificial intelligence Remember that the function inside units take as input the weighted sum, S, of the values coming from the units associated to it. The fun

Example calculation of entropy, Example Calculation: If we see an exam...

Example Calculation: If we see an example we are working with a set of examples like S = {s 1 ,s 2 ,s 3 ,s 4 } categorised with a binary categorisation of positives and negati

Explain segmentation, Explain segmentation? Segment memory addressing ...

Explain segmentation? Segment memory addressing divides memory into many segments. Each of these segments can be considered as a linear memory space. Every one of these segmen

Dram simm, The most common type of non-volatile memory is the ROM device. T...

The most common type of non-volatile memory is the ROM device. This device is read only and the data is masked into the chip during manufacture. Variations of the ROM are one off p

Produce an analysis model of the proposed system, Question: Read the fo...

Question: Read the following case study and answer the questions based on it. The local airline company needs to develop a system for controlling air traffic at the airport

What are the applications of edi in business, What are the applications of ...

What are the applications of EDI in business A.  Organistions that use EDI Extensive users of EDI contain: BHS- is a UK and European retailer dealing majorly in appare

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