本书是对4.4BSD操作系统的设计和实现的全面描述，在讨论设计理论的同时，也注重介绍实现的细节。
全书分为五个部分，共有14章。**部分介绍了BSD的历史，简单介绍了操作系统设计的几个基本方面，还介绍了内核服务的基本内容。第二部分介绍了进程管理和内存管理的内容。第三部分介绍I／O系统，包括本地和网络文件系统以及终端处理。第四部分介绍了进程间通信、网络通信以及网络协议。第五部分介绍了系统操作知识。
本书适合作为高等院校计算机专业操作系统课程教材，也适合开放系统下的管理人员和开发人员阅读参考。

Part 1 Overview 1

Chapter 1 History and Goals 3
1.1 History of the UNIX System 3
·Origins 3
·Research UNIX 4
·AT&T UNIX System Ⅲ and System V 7
·Other Organizations 8
·Berkeley Software Distributions 8
·UNIX in the World 10
1.2 BSD and Other Systems 10
·The Influence of the User Community 11
1.3 Design Goals of 4BSD 12
·4.2BSD Design Goals 13
·4.3BSD Design Goals 14
·4.4BSD Design Goals 15
1.4 Release Engineering 16
·References 17

Chapter 2 Design Overview of 4.4BSD 21
2.1 4.4BSD Facilities and the Kernel 21
·The Kernel 22
2.2 Kernel Organization 23
2.3 Kernel Services 25
2.4 Process Management 26
·Signals 27
·Process Groups and Sessions 28
2.5 Memory Management 29
·BSD Memory-Management Design Decisions 29
·Memory Management Inside the Kernel 31
2.6 I/O System 31
·Descriptors and I/O 32
·Descriptor Management 33
·Devices 34
·Socket IPC 35
·Scatter/Gather I/O 35
·Multiple Filesystem Support 36
2.7 Filesystems 36
2.8 Filestores 40
2.9 Network Filesystem 41
2.10 Terminals 42
2.11 Interprocess Communication 43
2.12 Network Communication 44
2.13 Network Implementation 44
2.14 System Operation 45
·Exercises 45
·Reference 46

Chapter 3 Kernel Services 49
3.1 Kernel Organization 49
·System Processes 49
·System Entry 50
·Run-Time Organization 50
·Entry to the Kernel 52
·Return from the Kernel 53
3.2 System Calls 53
·Result Handing 54
·Returning from a System Call 54
3.3 Traps and Interrupts 55
·Traps 55
·I/O Device Interrupts 55
·Software Interrupts 56
3.4 Clock Interrupts 57
·Statistics and Process Scheduling 58
·Timeouts 58
3.5 Memory-Management Services 60
3.6 Timing Services 63
·Real Time 63
·Adjustment of the Time 63
·External Representation 64
·Interval Time 64
3.7 User, Group, and Other Identifiers 65
·Host Identifiers 67
·Process Groups and Sessions 68
3.8 Resource Services 68
·Process Priorities 69
·Resource Utilization 69
·Resource Limits 70
·Filesystem Quotas 70
3.9 System-Operation Services 71
·Accounting 71
·Exercises 72
·References 73

Part 2 Processes 75

Chapter 4 Process Management 77
4.1 Introduction to Process Management 77
·Multiprogramming 78
·Scheduling 79
4.2 Process State 80
·The Process Structure 81
·The User Structure 85
4.3 Context Switching 87
·Process State 87
·Low-Level Context Switching 88
·Voluntary Context Switching 88
·Synchronization 91
4.4 Process Scheduling 92
·Calculations of Process Priority 93
·Process-Priority Routines 95
·Process Run Queues and Context Switching 96
4.5 Process Creation 98
4.6 Process Termination 99
4.7 Signals 100
·Comparison with POSIX Signals 103
·Posting of a Signal 104
·Delivering a Signal 106
4.8 Process Groups and Sessions 107
·Sessions 109
·Job Control 110
4.9 Process Debugging 112
·Exercises 114
·References 116

Chapter 5 Memory Management 117
5.1 Terminology 117
·Processes and Memory 118
·Paging 119
·Replacement Algorithms 120
·Working-Set Model 121
·Swapping 121
·Advantages of Virtual Memory 122
·Hardware Requirements for Virtual Memory 122
5.2 Overview of the 4.4 BSD Virtual-Memory System 123
5.3 Kernel Memory Management 126
·Kernel Maps and Submaps 127
·Kernel Address-Space Allocation 128
·Kernel Malloc 129
5.4 Per-Process Resources 132
·4.4BSD Process Virtual-Address Space 132
·Page-Fault Dispatch 134
·Mapping to Objects 134
·Objects 136
·Objects to Pages 137
5.5 Shared Memory 137
·Mmap Model 139
·Shared Mapping 141
·Private Mapping 142
·Collapsing of Shadow Chains 144
·Private Snapshots 145
5.6 Creation of a New Process 146
·Reserving Kernel Resources 147
·Duplication of the User Address Space 148
·Creation of a New Process Without Copying 149
5.7 Execution of a File 150
5.8 Process Manipulation of Its Address Space 151
·Change of Process Size 151
·File Mapping 152
·Change of Protection 154
5.9 Termination of a Process 154
5.10 The Pager Interface 156
·Vnode Pager 157
·Device Pager 159
·Swap Pager 160
5.11 Paging 162
5.12 Page Replacement 166
·Paging Parameters 168
·The Pageout Daemon 169
·Swapping 171
·The Swap-In Process 172
5.13 Portability 173
·The Role of the pmap Module 176
·Initialization and Startup 179
·Mapping Allocation and Deallocation 181
·Change of Access and Wiring Attributes for Mappings 184
·Management of Page-Usage Information 185
·Initialization of Physical Pages 186
·Management of Internal Data Structures 186
·Exercises 187
·References 188

Part 3 I/O System 191

Chapter 6 I/O System Overview 193
6.1 I/O Mapping from User to Device 193
·Device Drivers 195
·I/O Queuing 195
·Interrupt Handing 196
6.2 Block Devices 196
·Entry Points for Block-Device Drivers 197
·Sorting of Disk I/O Requests 198
·Disk Labels 199
6.3 Character Devices 200
·Raw Devices and Physical I/O 201
·Character-Oriented Devices 202
·Entry Points for Character-Device Drivers 203
6.4 Descriptor Management and Services 205
·Open File Entries 205
·Management of Descriptors 207
·File-Descriptor Locking 209
·Multiplexing I/O on Descriptors 211
·Implementation of Select 213
·Movement of Data Inside the Kernel 216
6.5 The Virtual-Filesystem Interface 218
·Contents of a Vnode 219
·Vnode Operations 220
·Pathname Translation 222
·Exported Filesystem Services 222
6.6 Filesystem-Independent Services 223
·The Name Cache 225
·Buffer Management 226
·Implementation of Buffer Management 229
6.7 Stackable Filesystems 231
·Simple Filesystem Layers 234
·The Union Mount Filesystem 235
·Other Filesystems 237
·Exercises 238
·References 240

Chapter 7 Local Filesytems 241
7.1 Hierarchical Filesystem Management 241
7.2 Structure of an Inode 243
·Inode Management 245
7.3 Naming 247
·Directories 247
·Finding of Names in Directories 249
·Pathname Translation 249
·Links 251
7.4 Quotas 253
7.5 File Locking 257
7.6 Other Filesystem Semantics 262
·Large File Sizes 262
·File Flags 263
·Exercises 264
·References 264

Chapter 8 Local Filestores 265
8.1 Overview of the Filestore 265
8.2 The Berkeley Fast Filesystem 269
·Organization of the Berkeley Fast Filesystem 269
·Optimization of Storage Utilization 271
·Reading and Writing to a File 273
·Filesystem Parameterization 275
·Layout Policies 276
·Allocation Mechanisms 277
·Block Clustering 281
·Synchronous Operations 284
8.3 The Log-Structured Filesystem 285
·Organization of the Log-Structure Filesystem 286
·Index File 288
·Reading of the Log 290
·Writing to the Log 291
·Block Accounting 292
·The Buffer Cache 294
·Directory Operations 295
·Creation of a File 296
·Reading and Writing to a File 297
·Filesystem Cleaning 297
·Filesystem Parameterization 300
·Filesystem-Crash Recovery 300
8.4 The Memory-Based Filesystem 302
·Organization of the Memory-Based Filesystem 303
·Filesystem Performance 305
·Future Work 305
·Exercises 306
·References 307

Chapter 9 The Network Filesystem 311
9.1 History and Overview 311
9.2 NFS Structure and Operation 314
·The NFS Protocol 316
·The 4.4BSD NFS Implementation 318
·Client-Server Interactions 321
·RPC Transport Issues 322
·Security Issues 324
9.3 Techniques for Improving Performance 325
·Leases 328
·Crash Recovery 332
·Exercises 333
·References 334

Chapter 10 Terminal Handing 337
10.1 Terminal-Processing Modes 338
10.2 Line Disciplines 339
10.3 User Interface 340
10.4 The tty Structure 342
10.5 Process Group, Sessions, and Terminal Control 343
10.6 C-lists 344
10.7 RS-232 and Modem Control 346
10.8 Terminal Operations 347
·Open 347
·Output Line Discipline 347
·Output Top Half 349
·Output Bottom Half 350
·Input Bottom Half 351
·Input Top Half 352
·The stop Routine 353
·The ioctl Routine 353
·Modem Transitions 354
·Closing of Terminal Devices 355
10.9 Other Line Disciplines 355
·Serial Line IP Disciplines 356
·Graphics Tablet Discipline 356
·Exercises 357
·References 357

Part 4 Interprocess Communication 359

Chapter 11 Interprocess Communication 361
11.1 Interprocess-Communication Model 362
·Use of Sockets 364
11.2 Implementation Structure and Overview 368
11.3 Memory Management 369
·Mbufs 369
·Storage-Management Algorithms 372
·Mbuf Utility Routines 373
11.4 Data Structures 374
·Communication Domains 375
·Sockets 376
·Socket Addresses 378
11.5 Connection Setup 380
11.6 Data Transfer 382
·Transmitting Data 383
·Receiving Data 385
·Passing Access Rights 388
·Passing Access Rights in the Local Domain 389
11.7 Socket Shutdown 390
·Exercises 391
·References 393

Chapter 12 Network Communication 395
12.1 Internal Structure 396
·Data Flow 397
·Communication Protocols 398
·Network Interfaces 400
12.2 Socket-to-Protocol Interface 405
·Protocol User-Request Routine 405
·Internal Requests 409
·Protocol Control-Output Routine 409
12.3 Protocol-Protocol Interface 410
·pr-output 411
·pr-input 411
·pr-ctlinput 411
12.4 Interface Between Protocol and Network Interface 412
·Packet Transmission 412
·Packet Reception 413
12.5 Routing 416
·Kernel Routing Tables 417
·Routing Lookup 420
·Routing Redirects 423
·Routing-Table Interface 424
·User-Level Routing Policies 425
·User-Level Routing Interface: Routing Socket 425
12.6 Buffering and Congestion Control 426
·Protocol Buffering Policies 427
·Queue Limiting 427
12.7 Raw Sockets 428
·Control Blocks 428
·Input Processing 429
·Output Processing 429
12.8 Additional Network-Subsystem Topics 429
·Out-of-Band Data 430
·Address Resolution Protocol 430
·Exercises 432
·References 433

Chapter 13 Network Protocols 435
13.1 Internet Network Protocols 436
·Internet Addresses 437
·Subnets 438
·Broadcast Addresses 441
·Internet Multicast 441
·Internet Ports and Associations 442
·Protocol Control Blocks 442
13.2 User Datagram Protocol(UDP) 443
·Initialization 443
·Output 444
·Input 445
·Control Operations 446
13.3 Internet Protocol(IP) 446
·Output 447
·Input 448
·Forwarding 449
13.4 Transmission Control Protocol(TCP) 451
·TCP Connection States 453
·Timers 459
·Estimation of Round-Trip Time 460
·Connection Establishment 461
·Connection Shutdown 463
13.6 TCP Input Processing 468
·Sending of Data 468
·Avoidance of the Silly-Window Syndrome 469
·Avoidance of Small Packets 470
·Delayed Acknowledgments and Window Updates 471
·Retransmit State 472
·Slow Start 472
·Source-Quench Processing 474
·Buffer and Window Sizing 474
·Avoidance of Congestion with Slow Start 475
·Fast Retransmission 476
13.8 Internet Control Message Protocol(ICMP) 477
13.9 OSI Implementation Issues 478
13.10 Summary of Networking and Interprocess Communication 480
·Creation of a Communication Channel 481
·Sending and Receiving of Data 482
·Termination of Data Transmission or Reception 483
·Exercises 484
·References 486

Part 5 System Operation 489

Chapter 14 System Startup 491
14.1 Overview 491
14.2 Bootstrapping 492
·The Boot Program 492
14.3 Kernel Initialization 493
·Assembly-Language Startup 494
·Machine-Dependent Initialization 495
·Message Buffer 495
·System Data Structures 496
14.4 Autoconfiguration 496
·Device Probing 498
·Device Attachment 499
·New Autoconfiguration Data Structures 499
·New Autoconfiguration Functions 501
·Device Naming 501
14.5 Machine-Independent Initialization 502
14.6 User-Level Initialization 505
·/sbin/init 505
·/etc/rc 505
·/usr/libexec/getty 506
·/usr/bin/login 506
14.7 System-Startup Topics 507
·Kernel Configuration 507
·System Shutdown and Autoreboot 507
·System Debugging 508
·Passage of Information To and From the Kernel 509
·Exercises 511
·References 511

Glossary 513
Index 551