The art of Linux kernel design: illustrating the operating system design principle and implementation

524 Pages·2014·9.66 MB·English

by  Dazhao, Chen, Ke, Feng, Liu, Tianhou, Qi, Song, Ruobing, Wu, Wenfeng, Liang, Yang, Lixiang

Art

The of
Linux KerneL

Design
Illustrating the Operating
System Design Principle
and Implementation
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Art

The of
Linux KerneL

Design
Illustrating the Operating
System Design Principle
and Implementation
Yang Lixiang • Liang Wenfeng
Chen Dazhao • Liu Tianhou,
Wu Ruobing • Song Qi • Feng Ke
CRC Press
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Contents
Preface xi
Author xiii
1. From Power-Up to the Main Function 1
1.1 Loading BIOS, Constructing Interrupt Vector Table, and Activating
Interrupt Service Routines in the Real Mode.............................2
1.1.1 Procedure for Starting BIOS..................................2
1.1.2 BIOS Loads the Interrupt Vector Table and Interrupt Service
Routines into Memory.......................................3
1.2 Loading the OS Kernel and Preparing for the Protected Mode .............4
1.2.1 Loading Bootsect............................................5
1.2.2 Loading the Second Part of Code— —Setup ....................7
1.2.3 Load the System Module ....................................12
1.3 Transfer to 32-Bit Mode and Prepare for the Main Function..............16
1.3.1 Disable Interrupts and Move System to 0x00000 ...............16
1.3.2 Set the Interrupt Descriptor Table and Global Descriptor
Table .................................................18
1.3.3 Open A20 and Achieve 32-Bit Addressing.....................20
v
1.3.4 Prepare for the Implementation of head.s in the
Protected Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..21
1.3.5 CPU Starts to Execute head.s ................................23
1.4 Summary ..........................................................43
2. Device Initialization and Process 0 Activation 45
2.1 Set Root Device 2 and Hard Disk......................................46
2.2 Set Up Physical Memory Layout, Buffer Memory, Ramdisk, and
Main Memory......................................................46
2.3 Ramdisk Setup and Initialization .....................................49
2.4 Initialization of the Memory Management Structure mem_map ..........52
2.5 Binding the Interrupt Service Routine .................................53
2.6 Initialize the Request Structure of the Block Device .....................58
2.7 Binding with the Interrupt Service Routine of Peripherals and
Establishing the Human–Computer Interaction Interface . . . . . . . . . . . . . . . .61
2.7.1 Set the Serial Port ..........................................61
2.7.2 Set the Display.............................................62
2.7.3 Set the Keyboard...........................................62
2.8 Time Setting .......................................................66
2.9 Initialize Process 0 ..................................................67
2.9.1 Initialization of Process 0 ...................................71
2.9.2 Set the Timer Interrupt .....................................73
2.9.3 Set the Entrance of System Call ..............................74
2.10 Initialize the Buffer Management Structure ............................75
2.11 Initialize the Hard Disk..............................................78
2.12 Initialize the Floppy Disk ............................................80
2.13 Enable the Interrupt.................................................80
2.14 Process 0 Moves from Privilege Level 0 to 3 and Becomes a
Real Process .................................................81
3. Creation and Execution of Process 1 85
3.1 Creation of Process 1 ................................................85
3.1.1 Preparation for Creating Process 1 ...........................85
3.1.2 Apply for an Idle Position and a Process Number for Process 1...91
3.1.3 Call Copy_process()........................................92
3.1.4 Set the Page Management of Process 1 ........................98
3.1.4.1 Set the Code Segment and Data Segment in the
Linear Address Space of Process 1..................99
3.1.4.2 Create the First Page Table for Process 1 and
Set the Corresponding Page Directory Entry........101
3.1.5 Process 1 Shares Files of Process 0...........................103
3.1.6 Set the Table Item in the GDT of Process 1 ...................104
3.1.7 Process 1 Is in Ready State to Complete the Creation of
Process 1.................................................105
vi Contents
3.2 Kernel Schedules a Process for the First Time..........................109
3.3 Turn to Process 1 to Execute.........................................113
3.3.1 Preparing to Install the Hard Disk File System by Process 1.....115
3.3.1.1 Process 1 Set hd_info of Hard Disk................115
3.3.1.2 Read the Hard Disk Boot Blocks to the Buffer.......116
3.3.1.3 Bind the Buffer Block with Request................125
3.3.1.4 Read the Hard Disk .............................129
3.3.1.5 Wait for Hard Disk Reading Data, Process
Scheduling, and Switch to Process 0 to Execute .....134
3.3.1.6 Hard Disk Interruption Occurs during the
Execution of Process 0...........................137
3.3.1.7 After Reading the Disk, Switch Process
Scheduling to Process 1..........................143
3.3.2 Process 1 Formats the Ramdisk and Replaces the Root Device
as the Ramdisk............................................146
3.3.3 Process 1 Loads the Root File System into the Root Device......149
3.3.3.1 Copying the Super Block of the Root Device to the
super_block[8]..................................152
3.3.3.2 Mount the i node of the Root Device to the Root
Device Super Block in super_block[8]..............157
3.3.3.3 Associate the Root File System with Process 1.......160
4. Creation and Execution of Process 2 165
4.1 Open the Terminal Device File and Copy the File Handle ...............165
4.1.1 Open the Standard Input Device File ........................165
4.1.1.1 File_table[0] is Mounted to Filp[0] in Process 1 .....165
4.1.1.2 Determine the Starting Point of Absolute Path......167
4.1.1.3 Acquiring the i node of Dev ......................172
4.1.1.4 Determine the i node of Dev as the Topmost
i node ......................................175
4.1.1.5 Acquire the i node of the tty0 File .................177
4.1.1.6 Determine tty0 as the Character Device File........180
4.1.1.7 Set file_table[0] .................................181
4.1.2 Open the Standard Output and Standard Error Output
Device File ...............................................182
4.2 Fork Process 2 and Switch to Process 2 to Execute......................187
4.3 Load the Shell Program.............................................198
4.3.1 Close the Standard Input File and Open the rc File ............198
4.3.2 Detect the Shell File .......................................201
4.3.2.1 Detect the Attribute of the i node .................201
4.3.2.2 Test File Header’s Attributes......................202
4.3.3 Prepare to Execute the Shell Program........................206
4.3.3.1 Load Parameters and Environment Variables.......206
4.3.3.2 Adjust the Management Structure of Process 2......210
4.3.3.3 Adjust EIP and ESP to Execute Shell...............212
Contents vii
4.3.4 Execute the Shell Program..................................214
4.3.4.1 Execute the First Page Program Loading by
the Shell....................................214
4.3.4.2 Map the Physical Address and Linear Address of
the Loading Page................................218
4.4 The System Gets to the Idle State.....................................219
4.4.1 Create the Update Process..................................219
4.4.2 Switch to the Shell Process..................................220
4.4.3 Reconstruction of the Shell.................................228
5. File Operation 231
5.1 Install the File System ..............................................231
5.1.1 Get the Super Block of Peripherals...........................232
5.1.2 Confirm the Mount Point of the Root File System .............234
5.1.3 Mount the Super Block with the Root File System .............235
5.2 Opening a File.....................................................236
5.2.1 Mount *Filp[20] in the User Process to File_table[64] ..........238
5.2.2 Get the File’s i node........................................239
5.2.2.1 Get the i node of the Directory File................239
5.2.2.2 Get the i node of the Target File...................248
5.2.3 Bind File i node with File_table[64]..........................249
5.3 Reading a File .....................................................250
5.3.1 Locate the Position of the Data Block in the Peripherals ........250
5.3.2 Data Block Is Read into the Buffer Block .....................254
5.3.3 Copy Data from the Buffer into the Process Memory...........255
5.4 Creating a New File ................................................256
5.4.1 Searching a File ...........................................256
5.4.2 Create a New i node for a File ...............................258
5.4.3 Create a New Content Item.................................260
5.5 Writing a File......................................................265
5.5.1 Locate the Position of the File to Be Written In................265
5.5.2 Apply for a Buffer Block....................................267
5.5.3 Copy Specified Data from the Process Memory to the
Buffer Block ..............................................268
5.5.4 Two Ways to Synchronize Data from the Buffer to the
Hard Disk................................................269
5.6 Modifying a File ...................................................272
5.6.1 Reposition the Current Operation Pointer of the File...........273
5.6.2 Modifying Files...........................................273
5.7 Closing a File......................................................275
5.7.1 Disconnecting Filp and File_table[64] in the Current Process......275
5.7.2 Releasing the Files’ i node ..................................277
5.8 Deleting a File .....................................................277
5.8.1 Checking the Deleting Conditions of Files....................278
5.8.2 Specific Deleting Work.....................................279
viii Contents
6. The User Process and Memory Management 283
6.1 Linear Address Protection ..........................................284
6.1.1 Patterns of the Process Linear Address Space .................284
6.1.2 Segment Base Addresses, Segment Limit, GDT, LDT, and
Privilege Level ............................................284
6.2 Paging............................................................287
6.2.1 Linear Address to Physical Address..........................287
6.2.2 Process Execution Paging ..................................289
6.2.3 Process Sharing the Page...................................295
6.2.4 Kernel Paging.............................................299
6.3 Complete Process of User Process from Creation to Exit ................302
6.3.1 Create Process str1.........................................302
6.3.2 Preparation to Load str1. ...................................315
6.3.3 Running and Loading of Process str1 ........................320
6.3.4 Exiting of Process str1......................................325
6.4 Multiple User Processes Run Concurrently............................331
6.4.1 Process Scheduling........................................331
6.4.2 Page Protection ...........................................336
7. Buffer and Multiprocess File 343
7.1 Function of Buffer..................................................343
7.2 Structure of Buffer .................................................345
7.3 The Function of b_dev, b_blocknr, and Request........................346
7.3.1 Ensure the Correctness of the Data Interaction between
Processes and Buffer Block .................................346
7.3.2 Let the Data Stay in the Buffer as Long as Possible .............353
7.4 Function of Uptodate and Dirt.......................................359
7.4.1 Function of b_uptodate ....................................359
7.4.2 Function of the b_dirt .....................................365
7.4.3 Function of the i_update, i_dirt, and s_dirt...................368
7.5 Function of the Count, Lock, Wait, Request ...........................370
7.5.1 Function of b_count.......................................370
7.5.2 Function of i_count .......................................372
7.5.3 Function of b_lock and *b_wait . . . . . . . . . . . . . . . . . . . . . . . . . . . . .375
7.5.4 Function of i_lock, i_wait, s_lock, and *s_wait................378
7.5.5 Function of Request .......................................381
7.6 Example 1: Process Waiting Queue of Buffer Block .....................383
7.7 Overall Look at the Buffer Block and the Request Item..................408
7.8 Example 2: Comprehensive Examples of Multiprocess Operating File.....411
8. Inter-Process Communication 431
8.1 Pipe Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
8.1.1 The Creation Process of the Pipe ............................433
8.1.2 Operation of Pipe .........................................439
Contents ix