nuttx/Documentation/implementation
Marco Casaroli ca8287e690 Documentation: describe the fork()/vfork()/task_fork() split
Documentation/guides/fork_vfork_migration.rst is new.  It says what changed
and why, gives the three primitives as a table, states plainly what breaks,
and answers "which replacement do I want?" from the reader's own reason for
having called fork() -- posix_spawn() or vfork() to run a program,
pthread_create() or task_fork() for a second flow of control that shares
memory, fork() itself for an independent copy, FORK_IS_TASK_FORK for code
that cannot be changed today.  It also documents the seven configuration
symbols, what an architecture has to implement to gain real fork(), and the
one visible consequence of moving the vfork() suspension into the kernel:
a waitpid() after a child that _exit()s can only report status where
CONFIG_SCHED_CHILD_STATUS is enabled.

reference/user/01_task_control.rst gains entries for fork() and task_fork()
and rewrites the one for vfork(), which described NuttX's limitations rather
than the interface's contract.  standards/posix.rst moves fork() from "No" to
"Cond." and vfork() from "Yes" to "Cond.", both being conditional on the
configuration now.  implementation/memory_configurations.rst no longer lists
fork() as unimplementable in the presence of address environments, which was
the whole point of that section's wish list.  Three long-standing typos in
that file are corrected while touching it, since codespell checks the whole
of any file a patch modifies.

Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>

Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 11:45:24 +02:00
..
bottomhalf_interrupt.rst docs/implementation: fix minor typos 2024-05-04 13:24:32 +08:00
cancellation_points.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
chip_h.rst !arch/stm32: move stm32l1 and finalize the directory split 2026-06-24 14:54:44 -03:00
context_switches.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
crc.rst Documentation: add CRC implementation details 2026-07-03 10:18:28 +08:00
critical_sections.rst style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
device_drivers.rst style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
device_nodes.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
disabling_interrupts.png Documentation: migrate "Effects of Disabling Interrupts or Pre-Emption on Response Latency" from wiki 2023-11-06 09:03:07 +08:00
disabling_preemption.png Documentation: migrate "Effects of Disabling Interrupts or Pre-Emption on Response Latency" from wiki 2023-11-06 09:03:07 +08:00
drivers_design.rst style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
file_descriptors.rst !arch/stm32: move stm32l1 and finalize the directory split 2026-06-24 14:54:44 -03:00
hardfaults.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
index.rst Documentation: add CRC implementation details 2026-07-03 10:18:28 +08:00
interrupt_controls.rst style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
ioctl.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
kernel_modules_vs_shared_libraries.rst Documentation: Fix kernel module wording. 2026-07-05 19:43:23 +02:00
kernel_threads_vs_pthreads.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
make_build_system.rst style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
memory_configurations.rst Documentation: describe the fork()/vfork()/task_fork() split 2026-07-30 11:45:24 +02:00
naming_arch_mcu_board_interfaces.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
naming_os_internals.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
normal_interrupt.png Documentation: migrate "Effects of Disabling Interrupts or Pre-Emption on Response Latency" from wiki 2023-11-06 09:03:07 +08:00
nuttx_initialization_sequence.rst !arch/stm32: move stm32l1 and finalize the directory split 2026-06-24 14:54:44 -03:00
nuttx_tasking.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
oneshot_timers_and_cpu_load.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
power_management.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
preemption_latency.rst Documentation: migrate "Effects of Disabling Interrupts or Pre-Emption on Response Latency" from wiki 2023-11-06 09:03:07 +08:00
processes_vs_tasks.rst Documentation: Fix various typos 2023-11-23 16:38:19 -08:00
short_delay.png doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
short_time_delays.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
signal_handlers.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
simulation.png doc: Add NuttX Simulation page from Confluence 2024-09-09 08:40:31 +08:00
simulation.rst Dockerfile & Docs: Change bitbucket.org/nuttx/tools to github.com 2026-05-25 08:34:45 -03:00
smp.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
syslog.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
task_exit_sequence.png doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
tasks_vs_threads.rst Documentation/sched: Add POSIX user identity transition docs 2026-06-12 08:13:23 +08:00
tickless_os.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
tls.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
usb.rst doc: Migrating the rest of documentation from cwiki. 2026-05-28 09:34:04 +08:00
user_identity.rst Documentation/sched: Add POSIX user identity transition docs 2026-06-12 08:13:23 +08:00