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 about layout cells, Q. Explain about Layout Cells? In Layout vi...

Q. Explain about Layout Cells? In Layout view you can draw layout cells and layout tables to define design areas of a document. This task is easier to accomplish if you prepare

Difference between visual check and parity check, Difference between Visual...

Difference between Visual check and Parity check Visual check This is checking for errors by comparing entered data with original document (NOTE: this is not the same as

Find values of x using 7s complement, Q. Perform binary subtraction, using ...

Q. Perform binary subtraction, using 1s & 2s complement: 1) 1010-1011 2) 0.1111-0.101 3) 11.11-10.111 Q.  (192.25)10 - (C0.C)16 = (x)7 Find values of x, using 7's compl

What is an i/o buffer, What is an I/O buffer? I/O buffer: One ty...

What is an I/O buffer? I/O buffer: One type of input-output requirement arises from devices which have a very high character density as disks and tapes. With these chara

When can a user program execution be interrupted, When can a user program e...

When can a user program execution be interrupted? It won't be desirable to interrupt a program when an instruction is being executed and is in a state such as instruction decod

Observing the existing system first hand, Observing the existing system fir...

Observing the existing system first hand This involves watching personnel using the existing system to find out precisely how it works. There are a number of disadvantages as

Modelsim, design a basic computer

design a basic computer

Instruction issue degree in superscalar processing, Q. Instruction Issue de...

Q. Instruction Issue degree in superscalar processing? The major concept in superscalar processing is how many instructions we are able to issue per cycle. If we are able to 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