实例介绍
【实例简介】
【实例截图】
【实例截图】
【核心代码】
Contents About This Guide..................................................................................................................................9 Typographical conventions........................................................................................................10 Technical support.....................................................................................................................12 Chapter 1: The Philosophy of the QNX Neutrino RTOS............................................................................13 An embeddable POSIX OS?.......................................................................................................14 Product scaling........................................................................................................................15 Why POSIX for embedded systems?...........................................................................................16 Why QNX Neutrino for embedded systems?.................................................................................18 Microkernel architecture...........................................................................................................19 The OS as a team of processes.......................................................................................20 A true kernel.................................................................................................................21 System processes..........................................................................................................21 Interprocess communication.....................................................................................................23 QNX Neutrino as a message-passing operating system......................................................23 Network distribution of kernels..................................................................................................24 Single-computer model..................................................................................................24 Flexible networking.......................................................................................................24 Chapter 2: The QNX Neutrino Microkernel.............................................................................................27 The implementation of the QNX Neutrino RTOS..........................................................................28 POSIX realtime and thread extensions.............................................................................28 System services.......................................................................................................................29 Threads and processes..............................................................................................................31 Thread attributes...........................................................................................................33 Thread life cycle...........................................................................................................35 Thread scheduling....................................................................................................................38 Scheduling priority........................................................................................................38 Scheduling policies.......................................................................................................40 IPC issues....................................................................................................................44 Thread complexity issues...............................................................................................44 Synchronization services...........................................................................................................46 Mutexes: mutual exclusion locks.....................................................................................46 Condvars: condition variables.........................................................................................48 Barriers........................................................................................................................49 Sleepon locks...............................................................................................................51 Reader/writer locks........................................................................................................51 Semaphores..................................................................................................................52 Synchronization via scheduling policy.............................................................................52 Synchronization via message passing..............................................................................53 Synchronization via atomic operations.............................................................................53 Synchronization services implementation.........................................................................54 Clock and timer services...........................................................................................................55 QNX® Neutrino® RTOS Time correction.............................................................................................................56 Timers..........................................................................................................................56 Interrupt handling....................................................................................................................59 Interrupt latency...........................................................................................................59 Scheduling latency........................................................................................................60 Nested interrupts..........................................................................................................60 Interrupt calls...............................................................................................................61 Chapter 3: Interprocess Communication (IPC)........................................................................................65 Synchronous message passing...................................................................................................66 Message copying......................................................................................................................68 Simple messages.....................................................................................................................71 Channels and connections........................................................................................................72 Pulses..........................................................................................................................73 Priority inheritance and messages...................................................................................73 Message-passing API................................................................................................................75 Robust implementations with Send/Receive/Reply.......................................................................76 Events....................................................................................................................................78 I/O notification..............................................................................................................78 Signals....................................................................................................................................80 Special signals..............................................................................................................81 Summary of signals.......................................................................................................83 POSIX message queues............................................................................................................85 Why use POSIX message queues?...................................................................................85 File-like interface..........................................................................................................85 Message-queue functions...............................................................................................86 Shared memory........................................................................................................................87 Shared memory with message passing.............................................................................87 Creating a shared-memory object....................................................................................88 mmap().....................................................................................................................89 Typed memory.........................................................................................................................92 Implementation-defined behavior....................................................................................92 Practical examples........................................................................................................96 Pipes and FIFOs......................................................................................................................98 Chapter 4: The Instrumented Microkernel..............................................................................................99 Instrumentation at a glance.....................................................................................................100 Event control.........................................................................................................................101 Modes of emission......................................................................................................101 Ring buffer.................................................................................................................102 Data interpretation.................................................................................................................103 System analysis with the IDE.......................................................................................103 Proactive tracing....................................................................................................................105 Chapter 5: Multicore Processing.........................................................................................................107 Asymmetric multiprocessing (AMP)..........................................................................................108 Contents Symmetric multiprocessing (SMP)...........................................................................................109 Booting an x86 SMP system.........................................................................................109 How the SMP microkernel works...................................................................................110 Critical sections..........................................................................................................111 Bound multiprocessing (BMP).................................................................................................113 A viable migration strategy...........................................................................................114 Choosing between AMP, SMP, and BMP...................................................................................115 Chapter 6: Process Manager...............................................................................................................117 Process management..............................................................................................................118 Process primitives.......................................................................................................118 Process loading...........................................................................................................122 Memory management.............................................................................................................123 Memory Management Units (MMUs).............................................................................123 Memory protection at run time.....................................................................................124 Quality control............................................................................................................126 Full-protection model..................................................................................................126 Locking memory..........................................................................................................127 Pathname management..........................................................................................................129 Resolving pathnames...................................................................................................129 Symbolic prefixes........................................................................................................133 File descriptor namespace...........................................................................................136 Chapter 7: Dynamic Linking...............................................................................................................139 Statically linked.....................................................................................................................140 Dynamically linked.................................................................................................................141 Augmenting code at runtime...................................................................................................142 How shared objects are used...................................................................................................143 Memory layout for a typical process..............................................................................144 Runtime linker............................................................................................................144 Loading a shared library at runtime...............................................................................145 Symbol name resolution...............................................................................................145 Chapter 8: Resource Managers...........................................................................................................147 What is a resource manager?...................................................................................................148 Why write a resource manager?.....................................................................................148 The types of resource managers....................................................................................149 Communication via native IPC......................................................................................150 Resource manager architecture...............................................................................................152 Message types............................................................................................................152 The resource manager shared library.............................................................................153 Summary..............................................................................................................................158 Chapter 9: Filesystems......................................................................................................................159 Filesystems and pathname resolution.......................................................................................160 Filesystem classes..................................................................................................................161 QNX® Neutrino® RTOS Filesystems as shared libraries.....................................................................................161 io-blk....................................................................................................................162 Filesystem limitations..................................................................................................165 Image filesystem....................................................................................................................166 RAM “filesystem”..................................................................................................................167 Embedded transaction filesystem (ETFS)..................................................................................168 Power-Safe filesystem.............................................................................................................172 Problems with existing disk filesystems.........................................................................172 Copy-on-write filesystem..............................................................................................172 Performance...............................................................................................................174 Encryption..................................................................................................................175 DOS Filesystem.....................................................................................................................180 FFS3 filesystem.....................................................................................................................183 NFS filesystem......................................................................................................................187 CIFS filesystem......................................................................................................................188 Universal Disk Format (UDF) filesystem...................................................................................189 Apple Macintosh HFS and HFS Plus........................................................................................190 Windows NT filesystem...........................................................................................................191 Inflator pass-through filesystem...............................................................................................192 Merkle filesystem...................................................................................................................193 Filesystem events...................................................................................................................195 Chapter 10: PPS...............................................................................................................................197 Persistence............................................................................................................................198 PPS objects...........................................................................................................................199 Publishing.............................................................................................................................200 Subscribing...........................................................................................................................201 Chapter 11: Character I/O..................................................................................................................203 Driver/io-char communication............................................................................................204 Device control........................................................................................................................206 Input modes..........................................................................................................................207 Raw input mode..........................................................................................................207 Edited input mode......................................................................................................208 Device subsystem performance................................................................................................211 Console devices.....................................................................................................................212 Serial devices........................................................................................................................213 Pseudo terminal devices (ptys)................................................................................................214 Chapter 12: Networking Architecture..................................................................................................215 Network manager (io-pkt*).................................................................................................216 Threading model....................................................................................................................218 Protocol module.....................................................................................................................219 Driver module........................................................................................................................220 Chapter 13: Native Networking (Qnet).................................................................................................221 Contents QNX Neutrino distributed........................................................................................................222 Name resolution and lookup....................................................................................................224 File descriptor (connection ID).....................................................................................224 Behind a simple open().............................................................................................225 Global Name Service (GNS).........................................................................................226 Network naming..........................................................................................................226 Redundant Qnet: Quality of Service (QoS) and multiple paths....................................................228 QoS policies...............................................................................................................228 Specifying QoS policies...............................................................................................230 Symbolic links............................................................................................................230 Examples..............................................................................................................................231 Chapter 14: TCP/IP Networking..........................................................................................................233 Structure of the TCP/IP manager.............................................................................................234 Socket API............................................................................................................................235 Database routines.......................................................................................................236 Multiple stacks......................................................................................................................238 IP filtering and NAT................................................................................................................239 NTP......................................................................................................................................240 Dynamic host configuration.....................................................................................................241 AutoIP.......................................................................................................................241 PPP over Ethernet..................................................................................................................242 /etc/autoconnect.........................................................................................................243 Chapter 15: High Availability.............................................................................................................245 An OS for HA.........................................................................................................................246 Inherent HA................................................................................................................246 HA-specific modules...................................................................................................246 Custom hardware support........................................................................................................247 Client library..........................................................................................................................248 Recovery example.......................................................................................................248 High Availability Manager........................................................................................................251 HAM and the Guardian................................................................................................251 HAM hierarchy............................................................................................................251 Publishing autonomously detected conditions................................................................254 Subscribing to autonomously published conditions.........................................................255 HAM as a “filesystem”.................................................................................................256 Multistage recovery.....................................................................................................256 HAM API....................................................................................................................256 Chapter 16: Adaptive Partitioning.......................................................................................................261 Why adaptive?.......................................................................................................................263 Benefits of adaptive partitioning..............................................................................................264 Engineering product performance.................................................................................264 Dealing with design complexity.....................................................................................264 Providing security........................................................................................................265 QNX® Neutrino® RTOS Debugging..................................................................................................................266 Adaptive partitioning thread scheduler.....................................................................................267 Appendix A: Glossary.........................................................................................................................269 Index...............................................................................................................................................285
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