Operating Systems Chapter on System Calls

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Questions and Answers

What is the primary purpose of the system call table?

To keep track of the memory usage of a program

To store the implementation code of system calls

To maintain addresses of system call routines (correct)

To display all available APIs

Which method of parameter passing does NOT limit the number or length of parameters being passed?

Placing parameters on the stack (correct)

Storing parameters in a block in memory (correct)

Using a high-level API to abstract system calls

Passing parameters in registers

How does a caller typically interact with system calls?

By manually managing memory allocations

Through direct access to system call implementations

By defining the parameters within the system call routine

By utilizing a high-level Application Program Interface (API) (correct)

What can be a consequence of having more parameters for a system call than available registers?

Parameters must be stored in memory or on the stack Signup and view all the answers

In the context of system calls, what does the caller necessarily not know?

The precise implementation details of system calls Signup and view all the answers

What is the purpose of a denial-of-service attack?

To render a system unavailable to legitimate users Signup and view all the answers

Which of the following best describes the function of system calls in an operating system?

They serve as a programming interface to request OS services Signup and view all the answers

What happens when a system call is executed?

The processor changes modes to execute privileged operations Signup and view all the answers

Why is it important for operating systems to manage user identifiers?

To distinguish among users for protection and security Signup and view all the answers

In what mode does execution occur on behalf of the operating system?

Kernel mode Signup and view all the answers

What is a primary advantage of a layered operating system?

Simplicity in debugging and extending the system. Signup and view all the answers

What characteristic does a microkernel provide for system reliability?

It runs all modules as separate user processes. Signup and view all the answers

What challenge is associated with designing a layered operating system?

Defining the appropriate roles and interactions of layers. Signup and view all the answers

How does communication occur between user modules in a microkernel architecture?

Via message passing. Signup and view all the answers

What will happen if an error occurs in a device driver in a microkernel system?

Only the specific component will be affected. Signup and view all the answers

Which of the following best describes a disadvantage of layering in an operating system?

Layer interactions need careful planning and definition. Signup and view all the answers

What is a potential consequence of a buggy audio driver in a monolithic operating system?

The entire system may crash due to invalid memory access. Signup and view all the answers

In a layered operating system, what assumption can be made after debugging the first layer?

The first layer is guaranteed to be error-free. Signup and view all the answers

What is a key advantage of using a microkernel system structure?

Increased reliability because less code runs in kernel mode Signup and view all the answers

How does the reincarnation server contribute to the microkernel system's reliability?

It automatically replaces faulty servers without user intervention Signup and view all the answers

What is a disadvantage associated with microkernel systems?

Performance overhead due to user space to kernel space communication Signup and view all the answers

Which of the following correctly describes the role of device drivers in a microkernel system?

They run in user mode and make kernel calls to access hardware. Signup and view all the answers

What common feature do modern implementations of operating systems share with loadable kernel modules?

Additional services can be linked in dynamically. Signup and view all the answers

In a microkernel system, what function do servers perform?

They process short messages from user programs to provide OS services. Signup and view all the answers

How does the modular kernel design differ from a truly layered system?

Modules can call any other module directly without restrictions. Signup and view all the answers

What role does the file server play in the architecture of a microkernel system?

It communicates with processes to facilitate file system operations. Signup and view all the answers

Which API is commonly used for POSIX-based systems?

POSIX API Signup and view all the answers

What is a primary function of the 'File management' category of system calls?

Create or delete files Signup and view all the answers

Which type of system call involves managing the attributes of devices?

Device management Signup and view all the answers

Which of the following is not a function of the 'Communications' category of system calls?

Setting process attributes Signup and view all the answers

What characterizes a simple structure operating system?

It is appropriate for small and restricted systems. Signup and view all the answers

Which of the following actions is included in the 'Process control' category of system calls?

Create and terminate processes Signup and view all the answers

Which structure is known as a straightforward operating system structure but lacks definition?

Simple structure Signup and view all the answers

What does the 'Device management' category of system calls enable?

Manage device access and attributes Signup and view all the answers

What happens if there is no active partition or the active partition's boot sector is invalid?

The MBR loads a secondary boot loader. Signup and view all the answers

Which of the following is an example of a secondary boot loader?

GRUB Signup and view all the answers

What is a potential drawback of using ROM for operating system storage?

Code execution in ROM is generally slower. Signup and view all the answers

How is the boot loader transferred from ROM to RAM?

By a routine loaded by the BIOS. Signup and view all the answers

What is the primary function of a Network Operating System (NOS)?

To support workstations, PCs, and terminals on a LAN. Signup and view all the answers

What distinguishes the Client Server Model from Peer to Peer networking in a NOS?

There are multiple clients and one dedicated server. Signup and view all the answers

Which statement about network operating systems is true?

They allow devices to share resources in a multiuser environment. Signup and view all the answers

Why has the traditional concept of a typical NOS evolved?

Most modern OSes have integrated network capabilities. Signup and view all the answers

Study Notes

Operating Systems Overview

An operating system (OS) is a program that manages computer hardware.
It acts as an intermediary between the user and the hardware.
The OS's purpose is to create a convenient and efficient environment for running programs.

Types of Operating Systems

Batch systems: Users submit jobs to the computer operator, and the output appears later.
Multiprogrammed systems: The OS keeps several jobs in memory simultaneously, increasing CPU utilization. The OS selects and executes one job; if it has to wait for an I/O operation, it switches to another job.
Time-sharing (multitasking) systems: Multiple users can interact with the computer simultaneously by switching between jobs rapidly. Each user gets the impression that the entire system is dedicated to their use.
Multiprocessor systems: Several processors work closely together, sharing resources like the bus, clock, and sometimes memory. This increases throughput.
Clustered systems: Multiple computers are coupled together to share storage and resources. This is often done for high availability—one device can take over operations from a failed device.
Real-time systems: These are special-purpose operating systems designed to meet rigid time requirements in dedicated applications.

System Calls

System calls are the interface between application programs and the operating system.
They allow application programs to request services from the OS.
System calls change the processor mode from user mode to kernel mode.
The OS can then perform restricted actions like accessing hardware or memory management.

Operating System Structures

Simple structure: A direct, non-modular approach.
Monolithic systems: A collection of procedures linked together into one program. Each procedure operates directly. Simple to design but difficult to maintain.
Layered systems: The OS is organized as a hierarchy of layers, one built atop the other. Each layer uses the services provided by the lower layers. Debugging is simpler.
Microkernel systems: The OS is structured around a small kernel, and other services run as processes. Communication between modules happens via interprocess communication (IPC). This allows for more reliability but may increase overhead.
Modular systems: Modules can be added or removed dynamically. This improves flexibility. The approach resembles layering.

Booting a Computer System

Hardware doesn't know where the operating system is located or how to load it.
A special program—a bootstrap loader—does this task.
It locates the kernel and loads it into memory, after which it executes the kernel.
In some systems, there are secondary boot loaders to load the kernel from different drives or partitions.
During booting processes, the BIOS interacts with hardware components to ensure they're functioning.

Network Operating Systems (NOS)

Network OSes coordinate computers across a LAN, allowing sharing of resources (like file servers) and handling multiple requests simultaneously.
There are two main types:
- Client-server model: A single server serves multiple clients.
- Peer-to-peer model: Each node acts as a server and a client.

Functions of an Operating System

Process management: Manages processes (programs in execution) and scheduling on CPUs to manage resources and ensure efficiency.
Memory management: Manages use of memory.
File management: Manages files and directories and provides primitives for manipulating them.
Device management: Manages I/O devices and drivers.
Secondary storage management: Manages secondary storage (like disks), including tasks such as free-space management, storage allocation, and disk scheduling.
Networking: Provides network services and features.
Security: Controls access to resources and protects the system against attacks.
Protection: Controls access to computer system resources, preventing unwanted or inappropriate access.

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Description

This quiz covers key concepts related to system calls in operating systems. It explores their purpose, methods of parameter passing, and the implications of parameter limits. Additionally, it addresses the role of system calls in user-module communication and overall system reliability.