slides02

Question 1

3 ways of allowing users to interact with machine

Answer 1

1. command-line interfaces - most fault tolerant
2. graphical user interfaces
3. touch screen interfaces

Question 2

system calls

Answer 2

• provides an interface to services made available by OS
• computer makes a system call when it makes a request to the OS’ kernel
• mode switch from user mode to kernel mode
• downside: slows down program

Question 3

OS architectures (3)

Answer 3

1. layered approach
2. monolithic structure
3. microkernel OS

Question 4

layered approach

Answer 4

• layer i only depends on layer i-1 or below
• hard to organize OS like this

Question 5

monolithic structure

Answer 5

• no structure
• all functionality thrown into kernel
• user+ kernel in same address space

Question 6

microkernel OS

Answer 6

• only basic functions offered by kernel - rest is in user mode
• kernel and user services in different address spaces (isolated)
• isolation: fault tolerant + intercommunication is expensive

Question 7

monolithic kernel vs microkernel

Answer 7

• file system always running in a monolithic kernel
• not the case for microkernels - not all components of file system are needed

Question 8

linux system structure

Answer 8

• applications interact with the kernel through standard C library
• kernel is monolithic structure in a single address space
• kernel split into modules for dynamic loading
• no message passing btwn modules - they all talk to the core
• core has important functions like CPU scheduling and memory management