part 2 os

Embedded Systems

Systems designed for specific tasks or functions, often with a fixed hardware configuration.

Loadable Kernel Modules

Modules that can be dynamically loaded into the kernel to provide additional functionality.

Linux

An open-source operating system kernel that can be customized and compiled for specific hardware configurations.

Bootstrap Program

Small piece of code that initiates the booting process by locating and loading the kernel.

Boot Loader

Software that loads the operating system into memory and starts its execution.

UEFI (Unified Extensible Firmware Interface)

Firmware interface that replaces BIOS in modern computer systems for faster booting.

GRUB

Open-source boot loader for Linux and UNIX systems that allows for flexible boot configurations.

Initramfs

Temporary RAM file system created during the boot process to support the real root file system.

Debugging

The process of finding and fixing errors in a system, including hardware and software issues.

Debugger

A tool that allows a programmer to explore the code and memory of a process at the time of failure, aiding in identifying and fixing issues.

Kernel

The core part of an operating system that manages the hardware and provides essential services for the user-level processes.

Crash

A failure in the kernel of an operating system, leading to error information being saved to a log file and the memory state being saved to a crash dump.

Performance Monitoring

The process of observing and measuring system behavior to identify bottlenecks and improve performance.

Counters

System activity tracking mechanisms used by operating systems to monitor various metrics like system calls, network operations, and disk operations.

Tracing

Tools that collect data for specific events, such as system-call invocations, providing a detailed view of system behavior.

BCC (BPF Compiler Collection)

A toolkit for dynamic kernel tracing in Linux systems, enabling debugging of interactions between user-level and kernel code with minimal performance impact.

Operating System

An environment that provides services for the execution of programs, interacting with users and managing system resources.

System Call

Interface for programs to request services from the operating system, categorized into process control, file management, device management, information maintenance, communications, and protection.

Standard C Library

Provides the system-call interface for UNIX and Linux systems, enabling programmers to access system-call services.

Monolithic Operating System

A structure where all functionality is in a single static binary file running in a single address space, known for efficiency but difficult to modify.

Layered Operating System

Divided into layers from hardware interface to user interface, though not ideal due to performance issues.

Microkernel Approach

Operating system design with a minimal kernel where most services run as user-level applications, communicating via message passing.

Modular Approach

Operating system design with services provided through loadable modules that can be added or removed during runtime.

Boot Loader

Loads the operating system into memory, initializes it, and starts system execution.

Linker

Combines relocatable object modules into a single binary executable file.

Loader

Loads the executable file into memory for execution on a CPU.

Operating System Services

The functions provided by an operating system can be categorized into two main groups.

Passing Parameters to the Operating System

Three general methods exist for passing parameters to the operating system.

Statistical Profiling

Describing how to obtain a statistical profile of a program's execution time and its importance.

System-Call Interface

Advantages and disadvantages of using the same system-call interface for files and devices manipulation.

Command Interpreter Development

Possibility of developing a new command interpreter using the system-call interface.

Android Compilation

Explanation of why Android uses ahead-of-time (AOT) compilation over just-in-time (JIT) compilation.

Interprocess Communication Models

Description of the two models of interprocess communication and their strengths and weaknesses.

API vs

Comparison between an application programming interface (API) and an application binary interface (ABI).

Mechanism and Policy Separation

Reasoning behind the desirability of separating mechanism and policy.

Layered System Components

Challenges in achieving a layered approach when two system components are interdependent.

Microkernel Design

Advantages, interactions, and disadvantages of the microkernel approach to system design.

Loadable Kernel Modules

Advantages of using loadable kernel modules in an operating system.

iOS vs

Similarities and differences between iOS and Android operating systems.

Java on Android

Explanation for not using the standard Java API and virtual machine for Java programs on Android systems.

Synthesis Operating System

Pros and cons of the Synthesis approach to kernel design and system-performance optimization.

dmesg command

A command used in Linux to display the message buffer of the kernel, providing information about recent system messages.

kernel module

A software component that can be dynamically loaded and unloaded into the Linux kernel to extend its functionality.

An include file in Linux that defines hashing functions for use within the kernel, including the constant value GOLDEN RATIO PRIME.

printk()

A function in Linux used to print messages to the kernel log buffer.

gcd

An include file in Linux that defines the function gcd() to calculate the greatest common divisor of two numbers.

jiffies

A global variable in the Linux kernel that maintains the number of timer interrupts since system boot.

HZ

A value defined in in Linux that determines the frequency of the timer interrupt, varying by machine type and architecture.