文件名称：vxworks_kernel_programmers_guide_6.9
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vxworks kernel guide 6.9
PART I: CORE TECHNOLOGIES 1 Overview ...................................................................................................... 3 1.1 Introduction ...................................................................................................................... 3 1.2 Kernel Architecture ......................................................................................................... 3 1.3 Related Documentation Resources .............................................................................. 4 1.4 VxWorks Configuration and Build .............................................................................. 5 2 VxWorks Configuration ............................................................................. 7 2.1 Introduction ...................................................................................................................... 7 2.2 About VxWorks Configuration ................................................................................... 7 2.2.1 Default Configuration and Images ................................................................. 8 2.2.2 Configuration With VxWorks Image Projects ............................................... 8 2.2.3 Configuration With VxWorks Source Build Projects ................................... 8 2.2.4 Configuration and Customization .................................................................. 8 2.2.5 Configuration Tools: Workbench and vxprj .................................................. 9 2.3 VxWorks Image Projects: VIPs .................................................................................... 9 2.3.1 VxWorks Components ...................................................................................... 10 Component Names .......................................................................................... 10 Basic VxWorks Components ............................................................................ 11 2.3.2 Device Driver Selection ................................................................................... 13 2.3.3 Component Bundles and Configuration Profiles ........................................ 14 2.3.4 VxWorks Component Reference .................................................................... 14 2.4 VxWorks Source Build Projects: VSBs ....................................................................... 14 2.4.1 Basic Operating System VSB Options ........................................................... 16 BSP-Specific Optimizations ............................................................................. 16 VxWorks Kernel Programmer's Guide, 6.9 iv Inconsistent Cache Mode Support .................................................................. 17 System Viewer Instrumentation Support ...................................................... 17 Real-Time Process Support .............................................................................. 17 Object Management Support ........................................................................... 17 Error Detection and Reporting Policy Hooks ............................................... 18 Task Switch Hook Support .............................................................................. 18 Task Create Hook Support ............................................................................... 18 CPU Power Management Support ................................................................. 19 Advanced Options ............................................................................................ 19 VxWorks BSP Validation Test Suite Support ................................................. 19 Symmetric Multiprocessor (SMP) Support ................................................... 19 SMP Determinism ............................................................................................. 19 MIPC Support .................................................................................................... 20 WRLOAD Support ............................................................................................ 20 Task-Specific Current Working Directory ...................................................... 20 Device Name Length ........................................................................................ 20 NFS V3 Server Optimization ........................................................................... 20 DOSFS Name Length Compatible .................................................................. 21 2.4.2 VSB Profiles ........................................................................................................ 21 2.4.3 Using VSB Projects to Create VxWorks Systems: Basic Steps .................... 21 2.4.4 Developing Kernel Applications for VSB Systems ..................................... 21 2.5 VxWorks Without Networking ..................................................................................... 22 2.6 Small-Footprint VxWorks Configuration ................................................................... 22 2.6.1 About Small-Footprint VxWorks .................................................................... 22 Kernel Facilities ................................................................................................. 22 Unsupported Facilities ..................................................................................... 23 BSPs ..................................................................................................................... 23 2.6.2 Configuring Small Footprint VxWorks .......................................................... 23 Small-Footprint VSB Profile and Options ...................................................... 24 VSB Options Specific to the Small-Footprint Profile .................................... 24 Small-Footprint VIP Profile and Components .............................................. 25 Optional Components for a Small Footprint VIP Project ............................ 25 2.6.3 Configuration and Build Steps for Small-Footprint VxWorks ................... 25 2.6.4 Writing Applications for Small-Footprint VxWorks .................................... 26 2.6.5 Example Application ........................................................................................ 26 2.6.6 Debugging Small-Footprint VxWorks ............................................................ 28 2.7 VxWorks Image Types ................................................................................................... 28 2.7.1 Default VxWorks Images ................................................................................ 29 2.7.2 VxWorks Images for Development and Production Systems ..................... 29 2.7.3 Boot Parameter Configuration for Standalone VxWorks Images .............. 30 2.8 Image Size Considerations ............................................................................................ 30 2.8.1 Boot Loader and Downloadable Image ......................................................... 30 2.8.2 Self-Booting Image ............................................................................................ 31 Contents v 3 Boot Loader ................................................................................................. 33 3.1 Introduction ...................................................................................................................... 33 3.2 Using a Default Boot Loader ......................................................................................... 34 3.3 Boot Loader Image Types ............................................................................................... 35 3.4 Boot Loader Shell ............................................................................................................ 35 3.4.1 Boot Loader Shell Commands ......................................................................... 36 3.5 Boot Parameters ............................................................................................................... 39 3.5.1 Displaying Current Boot Parameters ............................................................. 40 3.5.2 Description of Boot Parameters ...................................................................... 41 3.5.3 Changing Boot Parameters Interactively ....................................................... 44 3.6 Rebooting VxWorks ........................................................................................................ 45 3.7 Configuring and Building Boot Loaders .................................................................... 46 3.7.1 Boot Loader Profiles .......................................................................................... 46 3.7.2 Boot Loader Components ................................................................................ 47 3.7.3 Configuring Boot Parameters Statically ......................................................... 47 3.7.4 Enabling Networking for Non-Boot Interfaces ............................................. 48 3.7.5 Selecting a Boot Device ..................................................................................... 48 3.7.6 Reconfiguring Boot Loader Memory Layout for 32-Bit VxWorks ............. 50 Redefining the Boot Loader Link Address for Custom Boot Loaders ....... 50 Reconfiguring Memory Layout for a Persistent Memory Region ............. 51 3.7.7 Reconfiguring Boot Loader Memory Layout for 64-Bit VxWorks ............. 53 3.7.8 Building Boot Loaders ...................................................................................... 53 3.8 Installing Boot Loaders .................................................................................................. 53 3.9 Booting From a Network ............................................................................................... 53 3.10 Booting From a Target File System ............................................................................. 55 3.11 Booting From the Host File System Using TSFS ..................................................... 55 4 Kernel Applications .................................................................................... 57 4.1 Introduction ...................................................................................................................... 57 4.2 About Kernel Applications ........................................................................................... 58 4.3 Comparing Kernel Applications with RTP Applications ....................................... 59 4.4 C and C++ Libraries ........................................................................................................ 60 VxWorks Kernel Programmer's Guide, 6.9 vi 4.5 Kernel Application Structure ........................................................................................ 60 4.6 VxWorks Header Files .................................................................................................... 61 4.6.1 VxWorks Header File: vxWorks.h ................................................................... 61 4.6.2 Other VxWorks Header Files ........................................................................... 62 4.6.3 ANSI Header Files ............................................................................................ 62 4.6.4 ANSI C++ Header Files .................................................................................... 62 4.6.5 The -I Compiler Flag ......................................................................................... 62 4.6.6 VxWorks Nested Header Files ........................................................................ 62 4.6.7 VxWorks Private Header Files ........................................................................ 63 4.7 Custom Header Files ....................................................................................................... 63 4.8 Static Instantiation of Kernel Objects ......................................................................... 64 4.8.1 About Static Instantiation of Kernel Objects ................................................. 64 Kernel Objects That can be Instantiated Statically ....................................... 65 Static Instantiation and Code Size .................................................................. 65 Advantages of Static Instantiation .................................................................. 65 Applications and Static Instantiation ............................................................. 66 4.8.2 Scope Of Static Declarations ............................................................................ 66 4.8.3 Caveat With Regard to Macro Use .................................................................. 66 4.8.4 Static Instantiation of Tasks ............................................................................. 66 4.8.5 Static Instantiation Of Semaphores ................................................................ 67 4.8.6 Static Instantiation of Message Queues ......................................................... 68 4.8.7 Static Instantiation of Watchdog Timers ........................................................ 68 4.9 Boot-Time Hook Routine Facility ............................................................................... 69 Boot-Time Hook Routine Stubs and Components ....................................... 69 Using Boot-Time Hook Routine Stubs ........................................................... 70 4.10 Kernel Applications and Kernel Component Requirements ................................. 71 4.11 Building Kernel Application Modules ....................................................................... 71 4.12 Downloading Kernel Application Object Modules to a Target ............................. 72 4.13 Linking Kernel Application Object Modules with VxWorks ................................ 72 4.14 Configuring VxWorks to Run Applications Automatically ................................... 72 5 C++ Development ....................................................................................... 75 5.1 Introduction ...................................................................................................................... 75 5.2 Configuring VxWorks for C++ ..................................................................................... 76 5.3 C++ Header Files ............................................................................................................. 76 Contents vii 5.4 Spawning Tasks That Use C++ ..................................................................................... 76 5.5 Calls Between C and C++ Code .................................................................................... 77 5.6 C++ Compiler Caveats .................................................................................................... 77 5.7 Using C++ in Signal Handlers and ISRs ................................................................... 78 5.8 Downloadable Kernel Modules in C++ ..................................................................... 78 5.9 C++ Compiler Differences ............................................................................................ 78 5.9.1 Template Instantiation ...................................................................................... 78 5.9.2 Run-Time Type Information ............................................................................ 80 5.10 Namespaces ...................................................................................................................... 80 5.11 C++ Exception Handling ................................................................................................ 81 5.12 Standard Template Library (STL) ................................................................................ 81 5.13 C++ Demo Example ........................................................................................................ 81 6 Multitasking ................................................................................................. 83 6.1 Introduction ...................................................................................................................... 83 6.2 About Tasks and Multitasking ..................................................................................... 84 6.2.1 Task States and Transitions .............................................................................. 85 Tasks States and State Symbols ....................................................................... 85 Illustration of Basic Task State Transitions .................................................... 86 6.3 VxWorks System Tasks .................................................................................................. 87 Basic VxWorks Tasks ......................................................................................... 88 Tasks for Optional Components ..................................................................... 91 6.4 Task Scheduling .............................................................................................................. 93 6.4.1 Task Priorities .................................................................................................... 93 6.4.2 VxWorks Traditional Scheduler ...................................................................... 93 Priority-Based Preemptive Scheduling .......................................................... 94 Scheduling and the Ready Queue ................................................................. 94 Round-Robin Scheduling ................................................................................. 95 6.5 Task Creation and Management ................................................................................... 97 6.5.1 Task Creation and Activation .......................................................................... 97 Static instantiation of Tasks ............................................................................. 98 6.5.2 Task Names and IDs ......................................................................................... 98 Task Naming Rules ........................................................................................... 99 Task Name and ID Routines ............................................................................ 99 VxWorks Kernel Programmer's Guide, 6.9 viii 6.5.3 Inter-Process Communication With Public Tasks ......................................... 99 6.5.4 Task Creation Options ...................................................................................... 100 6.5.5 Task Stack ........................................................................................................... 102 Task Stack Protection ........................................................................................ 102 6.5.6 Task Information ............................................................................................... 103 6.5.7 Task Deletion and Deletion Safety .................................................................. 104 6.5.8 Task Execution Control ..................................................................................... 105 6.5.9 Task Scheduling Control .................................................................................. 106 6.5.10 Tasking Extensions: Using Hook Routines .................................................... 107 6.6 Task Error Status: errno .................................................................................................. 108 6.6.1 Layered Definitions of errno ........................................................................... 109 6.6.2 A Separate errno Value for Each Task ............................................................ 109 6.6.3 Error Return Convention ................................................................................. 109 6.6.4 Assignment of Error Status Values ................................................................. 110 6.7 Task Exception Handling ............................................................................................... 110 6.8 Shared Code and Reentrancy ........................................................................................ 111 6.8.1 Dynamic Stack Variables .................................................................................. 112 6.8.2 Guarded Global and Static Variables ............................................................. 112 6.8.3 Task-Specific Variables .................................................................................... 113 Thread-Local Variables: __thread Storage Class ........................................... 113 taskVarLib and Task Variables ........................................................................ 114 6.8.4 Multiple Tasks with the Same Main Routine ................................................ 114 7 Intertask and Interprocess Communication ............................................. 117 7.1 Introduction ...................................................................................................................... 117 7.2 About Intertask and Interprocess Communication .................................................. 118 7.3 Shared Data Structures ................................................................................................... 119 7.4 Interrupt Locks ............................................................................................................... 120 7.5 Task Locks ........................................................................................................................ 121 7.6 Semaphores ...................................................................................................................... 122 7.6.1 Inter-Process Communication With Public Semaphores ............................. 123 7.6.2 Semaphore Creation and Use .......................................................................... 123 Options for Scalable and Inline Semaphore Routines ................................ 125 Static Instantiation of Semaphores ................................................................. 125 Scalable and Inline Semaphore Take and Give Routines ........................... 126 Contents ix 7.6.3 Binary Semaphores ........................................................................................... 126 Mutual Exclusion .............................................................................................. 127 Synchronization ................................................................................................. 128 7.6.4 Mutual-Exclusion Semaphores ....................................................................... 129 Priority Inversion and Priority Inheritance ................................................... 129 Deletion Safety ................................................................................................... 132 Recursive Resource Access .............................................................................. 133 7.6.5 Counting Semaphores ...................................................................................... 134 7.6.6 Read/Write Semaphores ................................................................................. 134 Specification of Read or Write Mode .............................................................. 135 Precedence for Write Access Operations ....................................................... 136 Read/Write Semaphores and System Performance ..................................... 136 7.6.7 Special Semaphore Options ............................................................................. 136 Semaphore Timeout .......................................................................................... 136 Semaphores and Queueing .............................................................................. 137 Semaphores and VxWorks Events .................................................................. 137 7.7 Message Queues .............................................................................................................. 137 7.7.1 Inter-Process Communication With Public Message Queues ..................... 138 7.7.2 Message Creation and Use ............................................................................... 138 Static Instantiation of Message Queues ......................................................... 139 Message Queue Timeout .................................................................................. 139 Message Queue Urgent Messages .................................................................. 140 Message Queues and Queuing Options ........................................................ 140 7.7.3 Displaying Message Queue Attributes .......................................................... 141 7.7.4 Servers and Clients with Message Queues .................................................... 141 7.7.5 Message Queues and VxWorks Events .......................................................... 142 7.8 Pipes ................................................................................................................................... 142 7.8.1 Creating Pipes ................................................................................................... 142 7.8.2 Writing to Pipes from ISRs ............................................................................... 142 7.8.3 I/O Control Functions ...................................................................................... 143 7.9 VxWorks Events ............................................................................................................... 143 7.9.1 Configuring VxWorks for Events .................................................................... 144 7.9.2 About Event Flags and the Task Events Register ......................................... 144 7.9.3 Receiving Events ............................................................................................... 145 7.9.4 Sending Events .................................................................................................. 146 7.9.5 Inter-Process Communication With Events .................................................. 148 7.9.6 Events Routines ................................................................................................. 148 7.9.7 Code Example ................................................................................................... 149 7.9.8 Show Routines and Events .............................................................................. 149 VxWorks Kernel Programmer's Guide, 6.9 x 7.10 Inter-Process Communication With Public Objects ................................................. 149 Creating and Naming Public and Private Objects ....................................... 150 Example of Inter-process Communication With a Public Semaphore ...... 150 7.11 About VxWorks API Timeout Parameters .................................................................. 152 7.12 About Object Ownership and Resource Reclamation ............................................. 152 8 Signals, ISRs, and Watchdog Timers ........................................................ 155 8.1 Introduction ...................................................................................................................... 155 8.2 Signals .............................................................................................................................. 156 8.2.1 Configuring VxWorks for Signals .................................................................. 157 8.2.2 Basic Signal Routines ........................................................................................ 158 8.2.3 Queued Signal Routines .................................................................................. 159 8.2.4 Signal Events ...................................................................................................... 162 8.2.5 Signal Handlers ................................................................................................. 163 8.3 Interrupt Service Routines: ISRs ................................................................................. 166 8.3.1 Configuring VxWorks for ISRs ........................................................................ 166 Configuring the Interrupt Stack ...................................................................... 166 Adding Show Routine Support ....................................................................... 167 8.3.2 Writing ISRs ....................................................................................................... 167 Restrictions on ISRs ........................................................................................... 167 Facilities Available for ISRs .............................................................................. 169 Reserving High Interrupt Levels .................................................................... 170 8.3.3 System Clock ISR Modification ....................................................................... 171 8.3.4 Connecting ISRs to Interrupts ......................................................................... 171 8.3.5 Getting Information About ISRs ..................................................................... 172 8.3.6 Debugging ISRs ................................................................................................. 173 8.4 Watchdog Timers ............................................................................................................. 174 Static Instantiation of Watchdog Timers ........................................................ 175 8.4.1 Inter-Process Communication With Public Watchdog Timers ................... 176 9 POSIX Facilities .......................................................................................... 177 9.1 Introduction ...................................................................................................................... 178 9.2 Configuring VxWorks with POSIX Facilities ............................................................ 179 9.2.1 VxWorks Components for POSIX Facilities .................................................. 179 9.3 General POSIX Support ................................................................................................. 180 9.4 POSIX Header Files ........................................................................................................ 181 Contents xi 9.5 POSIX Namespace .......................................................................................................... 183 9.6 POSIX Clocks and Timers ............................................................................................. 183 9.7 POSIX Asynchronous I/O .............................................................................................. 186 9.8 POSIX Advisory File Locking ....................................................................................... 186 9.9 POSIX Page-Locking Interface ..................................................................................... 186 9.10 POSIX Threads ................................................................................................................ 187 9.10.1 POSIX Thread Attributes ................................................................................. 188 9.10.2 VxWorks-Specific Pthread Attributes ............................................................ 188 9.10.3 Specifying Attributes when Creating Pthreads ........................................... 189 9.10.4 POSIX Thread Creation and Management .................................................... 190 9.10.5 POSIX Thread Attribute Access ...................................................................... 190 9.10.6 POSIX Thread Private Data ............................................................................. 191 9.10.7 POSIX Thread Cancellation ............................................................................. 192 9.11 POSIX Thread Mutexes and Condition Variables .................................................... 193 9.11.1 Thread Mutexes ................................................................................................. 193 Protocol Mutex Attribute ................................................................................ 194 Priority Ceiling Mutex Attribute .................................................................... 195 9.11.2 Condition Variables .......................................................................................... 195 9.12 POSIX and VxWorks Scheduling ................................................................................. 196 9.12.1 Differences in POSIX and VxWorks Scheduling ........................................... 197 9.12.2 POSIX and VxWorks Priority Numbering ..................................................... 198 9.12.3 Default Scheduling Policy ................................................................................ 198 9.12.4 VxWorks Traditional Scheduler ...................................................................... 198 9.12.5 POSIX Threads Scheduler ................................................................................ 199 9.12.6 POSIX Scheduling Routines ............................................................................ 203 9.12.7 Getting Scheduling Parameters: Priority Limits and Time Slice ................ 204 9.13 POSIX Semaphores ......................................................................................................... 204 9.13.1 Comparison of POSIX and VxWorks Semaphores ....................................... 205 9.13.2 Using Unnamed Semaphores .......................................................................... 206 9.13.3 Using Named Semaphores .............................................................................. 208 9.14 POSIX Message Queues ................................................................................................. 211 9.14.1 Comparison of POSIX and VxWorks Message Queues ............................... 212 9.14.2 POSIX Message Queue Attributes .................................................................. 213 9.14.3 Displaying Message Queue Attributes .......................................................... 214 VxWorks Kernel Programmer's Guide, 6.9 xii 9.14.4 Communicating Through a Message Queue ................................................ 215 9.14.5 Notification of Message Arrival ..................................................................... 218 9.15 POSIX Signals .................................................................................................................. 222 9.16 POSIX Memory Management ....................................................................................... 222 10 Memory Management ................................................................................. 223 10.1 Introduction ...................................................................................................................... 223 10.2 32-Bit VxWorks Memory Layout ................................................................................. 224 10.2.1 Displaying Information About Memory Layout .......................................... 224 10.2.2 System Memory Map Without RTP Support ................................................ 224 10.2.3 System Memory Map with RTP Support ....................................................... 226 10.2.4 System RAM Autosizing .................................................................................. 228 10.2.5 Reserved Memory: User-Reserved Memory and Persistent Memory ...... 228 10.3 64-Bit VxWorks Memory Layout ................................................................................. 229 10.3.1 Displaying Information About Memory Layout .......................................... 230 10.3.2 Virtual Memory Regions .................................................................................. 230 Kernel System Virtual Memory Region ......................................................... 231 Kernel Virtual Memory Pool Region .............................................................. 232 Kernel Reserved Memory Region ................................................................... 232 Shared User Virtual Memory Region ............................................................. 232 RTP Private Virtual Memory Region .............................................................. 232 10.3.3 Global RAM Pool .............................................................................................. 233 10.3.4 Kernel Memory Map ........................................................................................ 233 Kernel System Memory .................................................................................... 235 Kernel Common Heap ...................................................................................... 235 DMA32 Heap ..................................................................................................... 235 User-Reserved Memory ................................................................................... 235 Persistent Memory ............................................................................................ 235 10.3.5 Reserved Memory Configuration: User-Reserved Memory and Persistent Memory .............................................................................................................. 236 10.3.6 System RAM Autosizing .................................................................................. 236 10.4 About VxWorks Memory Allocation Facilities ......................................................... 236 10.5 32-Bit VxWorks Heap and Memory Partition Management .................................. 237 10.5.1 Configuring the Kernel Heap and the Memory Partition Manager .......... 238 10.5.2 Basic Heap and Memory Partition Manager ................................................. 238 10.5.3 Full Heap and Memory Partition Manager ................................................... 238 10.6 64-Bit VxWorks Heap and Memory Partition Management .................................. 239 10.6.1 Kernel Common Heap ...................................................................................... 239 Contents xiii 10.6.2 Kernel Proximity Heap ..................................................................................... 240 10.6.3 DMA32 Heap ..................................................................................................... 240 10.7 SMP-Optimized Memory Allocation .......................................................................... 241 10.7.1 Configuration ..................................................................................................... 241 10.7.2 Usage scenarios ................................................................................................. 241 10.8 Memory Pools .................................................................................................................. 242 10.9 POSIX Memory Management ....................................................................................... 242 10.9.1 POSIX Memory Management APIs ................................................................ 243 10.9.2 POSIX Memory Mapping ................................................................................ 244 10.9.3 POSIX Memory Protection ............................................................................... 244 10.9.4 POSIX Memory Locking .................................................................................. 244 10.10 Memory Mapping Facilities .......................................................................................... 245 10.10.1 POSIX Memory-Mapped Files ........................................................................ 247 10.10.2 POSIX Shared Memory Objects ...................................................................... 247 10.10.3 Anonymous Memory Mapping ...................................................................... 247 10.10.4 Device Memory Objects ................................................................................... 248 10.10.5 Shared Data Regions ......................................................................................... 249 10.11 Virtual Memory Management ..................................................................................... 249 10.11.1 Configuring Virtual Memory Management .................................................. 250 10.11.2 Managing Virtual Memory Programmatically ............................................. 251 Modifying Page States ...................................................................................... 252 Making Memory Non-Writable ...................................................................... 253 Invalidating Memory Pages ............................................................................ 255 Locking TLB Entries .......................................................................................... 255 Page Size Optimization .................................................................................... 255 Setting Page States in ISRs ............................................................................... 256 10.11.3 Troubleshooting ................................................................................................. 256 10.12 Additional Memory Protection Features ................................................................... 257 10.12.1 Configuring VxWorks for Additional Memory Protection ......................... 257 10.12.2 Stack Overrun and Underrun Detection ........................................................ 258 10.12.3 Non-Executable Task Stack .............................................................................. 258 10.12.4 Text Segment Write Protection ........................................................................ 258 10.12.5 Exception Vector Table Write Protection ........................................................ 259 10.13 Memory Error Detection ................................................................................................ 259 10.13.1 Heap and Partition Memory Instrumentation .............................................. 259 10.13.2 Compiler Instrumentation: 32-Bit VxWorks .................................................. 264 VxWorks Kernel Programmer's Guide, 6.9 xiv 11 I/O System ................................................................................................... 269 11.1 Introduction ...................................................................................................................... 269 11.2 About the VxWorks I/O System ................................................................................... 270 Differences Between VxWorks and Host System I/O ................................. 270 11.3 Configuring VxWorks With I/O Facilities .................................................................. 271 11.4 I/O Devices, Named Files, and File Systems ............................................................ 272 11.5 Remote File System Access From VxWorks ............................................................... 273 NFS File System Access from VxWorks ......................................................... 273 Non-NFS Network File System Access from VxWorks WIth FTP or RSH 273 11.6 Basic I/O ............................................................................................................................ 275 11.6.1 File Descriptors .................................................................................................. 275 File Descriptor Table ......................................................................................... 276 11.6.2 Standard Input, Standard Output, and Standard Error .............................. 276 11.6.3 Standard I/O Redirection ................................................................................ 276 Issues with Standard I/O Redirection ........................................................... 277 11.6.4 Open and Close ................................................................................................. 278 11.6.5 Create and Remove ........................................................................................... 280 11.6.6 Read and Write .................................................................................................. 281 11.6.7 File Truncation ................................................................................................... 281 11.6.8 I/O Control ........................................................................................................ 282 11.6.9 Pending on Multiple File Descriptors with select( ) ..................................... 282 11.6.10 POSIX File System Routines ............................................................................ 284 11.7 Standard I/O ..................................................................................................................... 285 11.7.1 Configuring VxWorks With Standard I/O .................................................... 285 11.7.2 About printf( ), sprintf( ), and scanf( ) ............................................................ 286 11.7.3 About Standard I/O and Buffering ................................................................ 286 11.7.4 About Standard Input, Standard Output, and Standard Error .................. 287 11.8 Other Formatted I/O ....................................................................................................... 287 11.8.1 Output in Serial I/O Polled Mode: kprintf( ) ................................................ 287 Writing to User-Defined Storage Media With kprintf( ) and kputs( ) ....... 288 11.8.2 Additional Formatted I/O Routines ............................................................. 289 11.8.3 Message Logging ............................................................................................... 289 11.9 Asynchronous Input/Output ......................................................................................... 289 11.9.1 The POSIX AIO Routines ................................................................................. 290 Contents xv 11.9.2 AIO Control Block ............................................................................................. 291 11.9.3 Using AIO ........................................................................................................... 292 AIO with Periodic Checks for Completion ................................................... 292 Alternatives for Testing AIO Completion ..................................................... 294 12 Devices ........................................................................................................ 297 12.1 Introduction ...................................................................................................................... 297 12.2 About Devices in VxWorks ........................................................................................... 298 12.3 Serial I/O Devices: Terminal and Pseudo-Terminal Devices .................................. 299 tty Options .......................................................................................................... 299 12.3.1 Raw Mode and Line Mode .............................................................................. 300 12.3.2 tty Special Characters ....................................................................................... 300 12.3.3 I/O Control Functions ...................................................................................... 301 12.4 Pipe Devices ..................................................................................................................... 302 12.5 Pseudo I/O Device ........................................................................................................... 302 12.5.1 I/O Control Functions ...................................................................................... 303 12.6 Null Devices .................................................................................................................... 303 12.7 Block Devices ................................................................................................................... 303 12.7.1 XBD RAM Disk .................................................................................................. 305 12.7.2 SCSI Drivers ....................................................................................................... 306 Configuring SCSI Drivers ................................................................................ 306 Structure of the SCSI Subsystem ..................................................................... 307 Booting and Initialization ................................................................................ 308 Device-Specific Configuration Options ......................................................... 308 SCSI Configuration Examples ......................................................................... 310 Troubleshooting ................................................................................................. 312 12.8 Extended Block Device Facility: XBD ......................................................................... 313 12.8.1 XBD Disk Partition Manager ........................................................................... 313 12.8.2 XBD Block Device Wrapper ............................................................................. 314 12.8.3 XBD TRFS Component ..................................................................................... 314 12.9 PCMCIA ............................................................................................................................ 315 12.10 Peripheral Component Interconnect: PCI .................................................................. 315 12.11 Network File System (NFS) Devices ........................................................................... 315 12.11.1 I/O Control Functions for NFS Clients .......................................................... 316 12.12 Non-NFS Network Devices ........................................................................................... 317 VxWorks Kernel Programmer's Guide, 6.9 xvi 12.12.1 Creating Network Devices ............................................................................... 318 12.12.2 I/O Control Functions ...................................................................................... 318 12.13 Sockets ............................................................................................................................... 318 12.14 Internal I/O System Structure ....................................................................................... 319 12.14.1 Drivers ................................................................................................................ 321 The Driver Table and Installing Drivers ........................................................ 322 Example of Installing a Driver ........................................................................ 322 12.14.2 Devices ................................................................................................................ 323 The Device List and Adding Devices ............................................................. 323 Example of Adding Devices ............................................................................ 324 Deleting Devices ................................................................................................ 324 12.14.3 File Descriptors .................................................................................................. 327 File Descriptor Table ......................................................................................... 327 Example of Opening a File ............................................................................... 327 Example of Reading Data from the File ......................................................... 330 Example of Closing a File ................................................................................. 331 Implementing select( ) ...................................................................................... 331 Cache Coherency ............................................................................................... 334 13 Local File Systems ..................................................................................... 339 13.1 Introduction ...................................................................................................................... 339 13.2 File System Monitor ...................................................................................................... 341 Device Insertion Events .................................................................................... 342 XBD Name Mapping Facility .......................................................................... 343 13.3 Virtual Root File System: VRFS ................................................................................... 343 13.4 Highly Reliable File System: HRFS ............................................................................ 345 13.4.1 Configuring VxWorks for HRFS ..................................................................... 345 13.4.2 Configuring HRFS ............................................................................................ 346 13.4.3 Creating an HRFS File System ....................................................................... 347 Overview of HRFS File System Creation ....................................................... 347 HRFS File System Creation Steps ................................................................... 347 13.4.4 HRFS, ATA, and RAM Disk Examples .......................................................... 348 13.4.5 Optimizing HRFS Performance ...................................................................... 353 13.4.6 Transactional Operations and Commit Policies ......................................... 353 Automatic Commit Policy ............................................................................... 353 High-Speed Commit Policy ............................................................................. 354 Mandatory Commits ......................................................................................... 354 Rollbacks ............................................................................................................. 354 Programmatically Initiating Commits ........................................................... 354 13.4.7 File Access Time Stamps .................................................................................. 355 Contents xvii 13.4.8 Maximum Number of Files and Directories ................................................. 355 13.4.9 Working with Directories ................................................................................. 355 Creating Subdirectories .................................................................................... 355 Removing Subdirectories ................................................................................. 356 Reading Directory Entries ................................................................................ 356 13.4.10 Working with Files ............................................................................................ 356 File I/O Routines ............................................................................................... 356 File Linking and Unlinking ............................................................................. 356 File Permissions ................................................................................................. 357 13.4.11 I/O Control Functions Supported by HRFS ................................................. 357 13.4.12 Crash Recovery and Volume Consistency ..................................................... 358 Crash Recovery .................................................................................................. 358 Consistency Checking ...................................................................................... 358 13.4.13 File Management and Full Devices ................................................................ 358 13.5 MS-DOS-Compatible File System: dosFs .................................................................. 359 13.5.1 Configuring VxWorks for dosFs ..................................................................... 360 13.5.2 Configuring dosFs ............................................................................................ 361 13.5.3 Creating a dosFs File System ........................................................................... 362 Overview of dosFs File System Creation ....................................................... 362 dosFs File System Creation Steps ................................................................... 363 13.5.4 dosFs, ATA Disk, and RAM Disk Examples ................................................. 365 13.5.5 Optimizing dosFs Performance ...................................................................... 369 13.5.6 Working with Volumes and Disks .................................................................. 370 Accessing Volume Configuration Information ............................................. 370 Synchronizing Volumes .................................................................................... 370 13.5.7 Working with Directories ................................................................................. 370 Creating Subdirectories .................................................................................... 370 Removing Subdirectories ................................................................................. 371 Reading Directory Entries ................................................................................ 371 13.5.8 Working with Files ............................................................................................ 371 File I/O Routines ............................................................................................... 371 File Attributes .................................................................................................... 371 13.5.9 Disk Space Allocation Options ........................................................................ 373 Choosing an Allocation Method ..................................................................... 374 Using Cluster Group Allocation ..................................................................... 374 Using Absolutely Contiguous Allocation ...................................................... 374 13.5.10 Crash Recovery and Volume Consistency ..................................................... 376 13.5.11 I/O Control Functions Supported by dosFsLib ............................................ 376 13.5.12 Booting from a Local dosFs File System Using SCSI ................................... 378 13.6 Transaction-Based Reliable File System Support for dosFs: TRFS ....................... 380 VxWorks Kernel Programmer's Guide, 6.9 xviii 13.6.1 Configuring VxWorks With TRFS ................................................................... 380 13.6.2 Automatic Instantiation of TRFS .................................................................... 380 13.6.3 Formatting a Device for TRFS ......................................................................... 381 13.6.4 Using TRFS in Applications ............................................................................ 382 TRFS Code Examples ....................................................................................... 382 13.7 Raw File System: rawFs ................................................................................................. 383 13.7.1 Configuring VxWorks for rawFs ..................................................................... 383 13.7.2 Creating a rawFs File System .......................................................................... 383 13.7.3 Mounting rawFs Volumes ................................................................................ 384 13.7.4 rawFs File I/O ................................................................................................... 385 13.7.5 I/O Control Functions Supported by rawFsLib ........................................... 385 13.8 CD-ROM File System: cdromFs ................................................................................... 386 13.8.1 Configuring VxWorks for cdromFs ................................................................ 387 13.8.2 Creating and Using cdromFs ........................................................................... 387 13.8.3 I/O Control Functions Supported by cdromFsLib ...................................... 389 13.8.4 Version Numbers ............................................................................................... 390 13.9 Read-Only Memory File System: ROMFS ................................................................. 390 13.9.1 Configuring VxWorks with ROMFS ............................................................... 391 13.9.2 Adding a ROMFS Directory and File Content to VxWorks ........................ 391 13.9.3 Accessing Files in ROMFS ............................................................................... 392 13.9.4 Using ROMFS to Start Applications Automatically .................................... 392 13.10 Target Server File System: TSFS ................................................................................... 392 Socket Support ................................................................................................... 393 Error Handling .................................................................................................. 394 Configuring VxWorks for TSFS Use ............................................................... 394 Security Considerations ................................................................................... 394 Using the TSFS to Boot a Target ...................................................................... 395 14 Flash File System Support: TrueFFS ........................................................ 397 14.1 Introduction ...................................................................................................................... 397 14.2 Overview of Implementation Steps ............................................................................ 398 14.3 Creating a VxWorks System with TrueFFS ................................................................ 400 14.3.1 Selecting an MTD .............................................................................................. 400 14.3.2 Identifying the Socket Driver .......................................................................... 400 14.3.3 Configuring VxWorks with TrueFFS and File System ................................. 401 Including the Core TrueFFS Component ....................................................... 401 Including the MTD Component ...................................................................... 402 Contents xix Including the Translation Layer Component ................................................ 402 Including the Socket Driver ............................................................................. 403 Including the XBD Wrapper Component ...................................................... 403 Including File System Components ............................................................... 403 Including Utility Components ........................................................................ 403 14.3.4 Building the System .......................................................................................... 404 14.3.5 Formatting the Flash ......................................................................................... 404 Formatting With sysTffsFormat( ) .................................................................. 404 Formatting With tffsDevFormat( ) .................................................................. 405 14.3.6 Reserving a Region in Flash for a Boot Image .............................................. 406 Reserving a Fallow Region .............................................................................. 407 Writing the Boot Image to Flash ...................................................................... 408 14.3.7 Mounting the Drive .......................................................................................... 409 14.3.8 Creating a File System ...................................................................................... 409 14.3.9 Testing the Drive ............................................................................................... 410 14.4 Using TrueFFS Shell Commands ................................................................................. 410 14.5 Using TrueFFS With HRFS ............................................................................................