| This text discusses both philosophical and design issues, as well as details of the actual implementation. Often, the discussion starts at the system-call level and descends into the kernel. Tables and figures are used to clarify data structures and control flow. Pseudocode similar to the C language displays algorithms. Boldface font identifies program names and filesystem pathnames. Italics font introduces terms that appear in the glossary and identifies the names of system calls, variables, routines, and structure names. Routine names (other than system calls) are further identified by the name followed by a pair of parenthesis (e.g., malloc() is the name of a routine, whereas argv is the name of a variable). The book is divided into five parts, organized as follows: Part I, Overview Three introductory chapters provide the context for the complete operating system and for the rest of the book. Chapter 1, History and Goals, sketches the historical development of the system, emphasizing the system's research orientation. Chapter 2, Design Overview of FreeBSD, describes the services offered by the system and outlines the internal organization of the kernel. It also discusses the design decisions that were made as the system was developed. Sections 2.3 through 2.14 in Chapter 2 give an overview of their corresponding chapter. Chapter 3, Kernel Services, explains how system calls are done and describes in detail several of the basic services of the kernel. Part II, Processes The first chapter in this part Chapter 4, Process Management lays the foundation for later chapters by describing the structure of a process, the algorithms used for scheduling the execution of the threads that make up a process, and the synchronization mechanisms used by the system to ensure consistent access to kernel-resident data structures. In Chapter 5, Memory Management, the virtual-memory-management system is discussed in detail. Part III, I/O System First, Chapter 6, I/O System Overview, explains the system interface to I/O and describes the structure of the facilities that support this interface. Following this introduction are four chapters that give the details of the main parts of the I/O system. Chapter 7, Devices, gives a description of the I/O architecture of the PC and describes how the I/O subsystem is managed and how the kernel initially maps out and later manages the arrival and departure of connected devices. Chapter 8, Local Filesystems, details the data structures and algorithms that implement filesystems as seen by application programs as well as how local filesystems are interfaced with the device interface described in Chapter 7. Chapter 9, The Network Filesystem, explains the network filesystem from both the server and client perspectives. Chapter 10, Terminal Handling, discusses support for character terminals and provides a description of the pseudo-terminal device driver. Part IV, Interprocess Communication Chapter 11, Interprocess Communication, describes the mechanism for providing communication between related or unrelated processes. Chapters 12 and 13, Network Communication and Network Protocols, are closely related because the facilities explained in the former are implemented by specific protocols, such as the TCP/IP protocol suite, explained in the latter. Part V, System Operation Chapter 14, Startup and Shutdown, discusses system startup and shutdown and explains system initialization at the process level from kernel initialization to user login.
The book is intended to be read in the order that the chapters are presented, but the parts other than Part I are independent of one another and can be read separately. Chapter 14 should be read after all the others, but knowledgeable readers may find it useful independently. At the end of the book are a Glossary with brief definitions of major terms and an Index. Each chapter contains a Reference section with citations of related material. |
