source: rtems-docs/c-user/config/posix-api.rst @ 9ba26e7

.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 2020, 2021 embedded brains GmbH (http://www.embedded-brains.de)
.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)

.. This file is part of the RTEMS quality process and was automatically
.. generated.  If you find something that needs to be fixed or
.. worded better please post a report or patch to an RTEMS mailing list
.. or raise a bug report:
..
.. https://www.rtems.org/bugs.html
..
.. For information on updating and regenerating please refer to the How-To
.. section in the Software Requirements Engineering chapter of the
.. RTEMS Software Engineering manual.  The manual is provided as a part of
.. a release.  For development sources please refer to the online
.. documentation at:
..
.. https://docs.rtems.org

.. Generated from spec:/acfg/if/group-posix

POSIX API Configuration
=======================

This section describes configuration options related to the POSIX API.  Most
POSIX API objects are available by default since RTEMS 5.1.  The queued signals
and timers are only available if RTEMS was built with the enable POSIX
build configuration option.

.. Generated from spec:/acfg/if/max-posix-keys

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_KEYS

.. _CONFIGURE_MAXIMUM_POSIX_KEYS:

CONFIGURE_MAXIMUM_POSIX_KEYS
----------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_KEYS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Keys that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

.. Generated from spec:/acfg/if/max-posix-key-value-pairs

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS

.. _CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS:

CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS
---------------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is
:ref:`CONFIGURE_MAXIMUM_POSIX_KEYS` *
( :ref:`CONFIGURE_MAXIMUM_TASKS` +
:ref:`CONFIGURE_MAXIMUM_POSIX_THREADS` ).

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of key
value pairs used by POSIX API Keys that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

A key value pair is created by :c:func:`pthread_setspecific` if the value
is not `NULL <https://en.cppreference.com/w/c/types/NULL>`_, otherwise it is deleted.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

.. Generated from spec:/acfg/if/max-posix-message-queues

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES

.. _CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES:

CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES
--------------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Message Queues that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.  You have to account for the memory used to
store the messages of each message queue, see
:ref:`CONFIGURE_MESSAGE_BUFFER_MEMORY`.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option shall be small enough so that the RTEMS
  Workspace size calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

.. Generated from spec:/acfg/if/max-posix-queued-signals

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS

.. _CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS:

CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS
--------------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Queued Signals that can be concurrently active.

.. rubric:: NOTES:

Unlimited objects are not available for queued signals.

Queued signals are only available if RTEMS was built with the POSIX API
build configuration option enabled.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option shall be small enough so that the RTEMS
  Workspace size calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

* The value of the configuration option shall be zero if the POSIX API is not
  enabled (e.g. RTEMS was built without the ``RTEMS_POSIX_API = True`` build
  configuration option).  Otherwise a compile time error in the configuration
  file will occur.

.. Generated from spec:/acfg/if/max-posix-semaphores

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_SEMAPHORES

.. _CONFIGURE_MAXIMUM_POSIX_SEMAPHORES:

CONFIGURE_MAXIMUM_POSIX_SEMAPHORES
----------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_SEMAPHORES``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Named Semaphores that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

Named semaphores are created with :c:func:`sem_open`.  Semaphores
initialized with :c:func:`sem_init` are not affected by this
configuration option since the storage space for these semaphores is
user-provided.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option shall be small enough so that the RTEMS
  Workspace size calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

.. Generated from spec:/acfg/if/max-posix-shms

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_SHMS

.. _CONFIGURE_MAXIMUM_POSIX_SHMS:

CONFIGURE_MAXIMUM_POSIX_SHMS
----------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_SHMS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Shared Memory objects that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option shall be small enough so that the RTEMS
  Workspace size calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

.. Generated from spec:/acfg/if/max-posix-threads

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_THREADS

.. _CONFIGURE_MAXIMUM_POSIX_THREADS:

CONFIGURE_MAXIMUM_POSIX_THREADS
-------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_THREADS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Threads that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

This calculations for the required memory in the RTEMS Workspace for threads
assume that each thread has a minimum stack size and has floating point
support enabled.  The configuration option :ref:`CONFIGURE_EXTRA_TASK_STACKS` is used
to specify thread stack requirements **above** the minimum size required.

The maximum number of Classic API Tasks is specified by
:ref:`CONFIGURE_MAXIMUM_TASKS`.

All POSIX threads have floating point enabled.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal to zero.

* The value of the configuration option shall be less than or equal to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size of the
  memory available to the application.

* The value of the configuration option shall be small enough so that the task
  stack space calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

.. Generated from spec:/acfg/if/max-posix-timers

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MAXIMUM_POSIX_TIMERS

.. _CONFIGURE_MAXIMUM_POSIX_TIMERS:

CONFIGURE_MAXIMUM_POSIX_TIMERS
------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MAXIMUM_POSIX_TIMERS``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is 0.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX
API Timers that can be concurrently active.

.. rubric:: NOTES:

This object class can be configured in unlimited allocation mode, see
:ref:`ConfigUnlimitedObjects`.

Timers are only available if RTEMS was built with the POSIX API build
configuration option enabled.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be greater than or equal
to zero.

* The value of the configuration option shall be less than or equal
to 65535.

* The value of the configuration option shall be less than or equal to a
  BSP-specific and application-specific value which depends on the size
  of the memory available to the application.

* The value of the configuration option may be defined through
  :c:func:`rtems_resource_unlimited` the enable unlimited objects for the
  object class, if the value passed to :c:func:`rtems_resource_unlimited`
  satisfies all other constraints of the configuration option.

* The value of the configuration option shall be zero if the POSIX API
is not
  enabled (e.g. RTEMS was built without the ``RTEMS_POSIX_API = True``
  build configuration option).  Otherwise a compile time error in the
  configuration
  file will occur.

.. Generated from spec:/acfg/if/min-posix-thread-stack-size

.. raw:: latex

    \clearpage

.. index:: CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE
.. index:: minimum POSIX thread stack size

.. _CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE:

CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE
-----------------------------------------

.. rubric:: CONSTANT:

``CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE``

.. rubric:: OPTION TYPE:

This configuration option is an integer define.

.. rubric:: DEFAULT VALUE:

The default value is two times the value of
:ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE`.

.. rubric:: DESCRIPTION:

The value of this configuration option defines the minimum stack size in
bytes for every POSIX thread in the system.

.. rubric:: CONSTRAINTS:

The following constraints apply to this configuration option:

* The value of the configuration option shall be small enough so that the task
  stack space calculation carried out by ``<rtems/confdefs.h>`` does not
  overflow an integer of type `uintptr_t
  <https://en.cppreference.com/w/c/types/integer>`_.

* The value of the configuration option shall be greater than or equal to a
  BSP-specific and application-specific minimum value.