nuttx/Documentation/implementation/index.rst

======================
Implementation Details
======================

.. toctree::
   :maxdepth: 2
   :caption: Contents:
   
   bottomhalf_interrupt.rst
   cancellation_points.rst
   chip_h.rst
   context_switches.rst
   crc.rst
   critical_sections.rst
   device_drivers.rst
   device_nodes.rst
   drivers_design.rst
   file_descriptors.rst
   file_permission.rst
   hardfaults.rst
   interrupt_controls.rst
   ioctl.rst
   kernel_modules_vs_shared_libraries.rst
   kernel_threads_vs_pthreads.rst
   make_build_system.rst
   memory_configurations.rst
   naming_arch_mcu_board_interfaces.rst
   naming_os_internals.rst
   nuttx_initialization_sequence.rst
   nuttx_tasking.rst
   oneshot_timers_and_cpu_load.rst
   power_management.rst
   preemption_latency.rst
   processes_vs_tasks.rst
   short_time_delays.rst
   signal_handlers.rst
   simulation.rst
   smp.rst
   syslog.rst
   tasks_vs_threads.rst
   tickless_os.rst
   tls.rst
   user_identity.rst
   usb.rst
Documentation: migrate "Linux Processes vs NuttX Tasks" from wiki link: https://cwiki.apache.org/confluence/display/NUTTX/Linux+Processes+vs+NuttX+Tasks 2023-11-04 20:41:19 +01:00			`======================`
			`Implementation Details`
			`======================`

			`.. toctree::`
			`:maxdepth: 2`
			`:caption: Contents:`

doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`bottomhalf_interrupt.rst`
			`cancellation_points.rst`
			`chip_h.rst`
			`context_switches.rst`
Documentation: add CRC implementation details Add a new section under Implementation Details explaining the CRC32 variants available in NuttX, including the difference between the native crc32() and the new Linux/zlib-compatible crc32_ieee(). Signed-off-by: hanzhijian <hanzhijian@zepp.com> 2026-07-02 09:30:59 +08:00			`crc.rst`
Documentation: migrate "SMP Critical Sections" from wiki links: https://cwiki.apache.org/confluence/display/NUTTX/SMP+Critical+Sections 2023-11-04 21:23:55 +01:00			`critical_sections.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`device_drivers.rst`
			`device_nodes.rst`
			`drivers_design.rst`
			`file_descriptors.rst`
Documentation: describe FS permission interface and mount-crossing Document inode_checkperm / inode_checkpathperm, mountpoint traverse vs open semantics, and the optional mountpt_operations.permission hook in file_permission.rst. Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com> 2026-08-02 17:54:38 +00:00			`file_permission.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`hardfaults.rst`
Documentation: migrate "Per-Thread Interrupt Controls" from wiki link: https://cwiki.apache.org/confluence/display/NUTTX/Per-Thread+Interrupt+Controls 2023-11-05 10:15:43 +01:00			`interrupt_controls.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`ioctl.rst`
			`kernel_modules_vs_shared_libraries.rst`
			`kernel_threads_vs_pthreads.rst`
			`make_build_system.rst`
			`memory_configurations.rst`
			`naming_arch_mcu_board_interfaces.rst`
			`naming_os_internals.rst`
			`nuttx_initialization_sequence.rst`
			`nuttx_tasking.rst`
			`oneshot_timers_and_cpu_load.rst`
			`power_management.rst`
Documentation: migrate "Effects of Disabling Interrupts or Pre-Emption on Response Latency" from wiki link: https://cwiki.apache.org/confluence/display/NUTTX/Effects+of+Disabling+Interrupts+or+Pre-Emption+on+Response+Latency 2023-11-05 10:16:13 +01:00			`preemption_latency.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`processes_vs_tasks.rst`
			`short_time_delays.rst`
			`signal_handlers.rst`
doc: Add NuttX Simulation page from Confluence 2024-09-08 19:19:00 -03:00			`simulation.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`smp.rst`
			`syslog.rst`
			`tasks_vs_threads.rst`
			`tickless_os.rst`
			`tls.rst`
Documentation/sched: Add POSIX user identity transition docs Adds comprehensive documentation for the POSIX three-tier user identity model (real, effective, saved-set IDs) enabled by CONFIG_SCHED_USER_IDENTITY. * Updates sched/Kconfig with detailed help text explaining the config. * Adds user_identity.rst to formally document credential inheritance and the privilege transition rules for setuid(), seteuid(), setgid(), and setegid(). * Updates tasks_vs_threads.rst to list credentials as a shared task group resource. Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com> 2026-06-11 19:48:15 +00:00			`user_identity.rst`
doc: Migrating the rest of documentation from cwiki. * This completes task list in https://github.com/apache/nuttx/issues/11127. * This preserves selected content from cwiki and moves it to new docs. * Most pages are simple copy-paste with a simple RST formatting updates, with minor updates. * Content update / reorganization will follow later on when needed. * Files added (or updated title from cwiki -> current docs): * Documentation/implementation: * index. * cancellation_points. * Asynchronous vs. Synchronous Context Switches -> context_switches.rst. * ARMv7-M Hardfaults, SVCALL, and Debuggers -> hardfatuls.rst. * chip.h FAQ -> chip_h.rst. * Debug Output (SYSLOG) Issues -> syslog.rst. * Detaching File Descriptors -> file_descriptors.rst. * device_nodes.rst. * Dynamic Clocking -> power_management.rst. * ENOTTY ioctl() Return Value -> ioctl.rst. * memory_configurations.rst. * kernel_modules_vs_shared_libraries.rst. * NAKing USB OUT/IN Tokens -> usb.rst. * naming_arch_mcu_board_interfaces.rst. * naming_os_internals.rst. * nuttx_tasking.rst. * oneshot_timers_and_cpu_load.rst. * nuttx_initialization_sequence.rst. * short_time_delays.rst. * Signal Handler Tour -> signal_handlers.rst. * smp.rst. * syslog.rst. * Task Exit Sequence -> nuttx_tasking.rst. * tasks_vs_threads.rst. * tls.rst. * tickless_os.rst. * Why Can't Kernel Threads Have pthreads -> kernel_threads_vs_pthreads.rst. * Documentation/components/filesystem: * smartfs.rst. Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info> 2026-05-16 13:54:41 +02:00			`usb.rst`