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258 lines
7.9 KiB
ReStructuredText
258 lines
7.9 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-SA-4.0
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.. Copyright (C) 2020, 2022 embedded brains GmbH (http://www.embedded-brains.de)
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.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
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.. This file is part of the RTEMS quality process and was automatically
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.. generated. If you find something that needs to be fixed or
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.. worded better please post a report or patch to an RTEMS mailing list
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.. or raise a bug report:
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..
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.. https://www.rtems.org/bugs.html
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..
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.. For information on updating and regenerating please refer to the How-To
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.. section in the Software Requirements Engineering chapter of the
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.. RTEMS Software Engineering manual. The manual is provided as a part of
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.. a release. For development sources please refer to the online
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.. documentation at:
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..
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.. https://docs.rtems.org
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.. Generated from spec:/acfg/if/group-idle
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Idle Task Configuration
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=======================
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This section describes configuration options related to the idle tasks.
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.. Generated from spec:/acfg/if/idle-task-body
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.. raw:: latex
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\clearpage
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.. index:: CONFIGURE_IDLE_TASK_BODY
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.. _CONFIGURE_IDLE_TASK_BODY:
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CONFIGURE_IDLE_TASK_BODY
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------------------------
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.. rubric:: CONSTANT:
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``CONFIGURE_IDLE_TASK_BODY``
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.. rubric:: OPTION TYPE:
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This configuration option is an initializer define.
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.. rubric:: DEFAULT VALUE:
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If the :ref:`CONFIGURE_DISABLE_BSP_SETTINGS` configuration option is not defined and
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:c:macro:`BSP_IDLE_TASK_BODY` is provided by the
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:term:`BSP`, then the default value is defined by
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:c:macro:`BSP_IDLE_TASK_BODY`, otherwise the default value is
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``_CPU_Thread_Idle_body``.
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.. rubric:: DESCRIPTION:
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The value of this configuration option initializes the IDLE thread body.
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.. rubric:: NOTES:
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IDLE threads shall not block. A blocking IDLE thread results in undefined
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system behaviour because the scheduler assume that at least one ready thread
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exists.
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IDLE threads can be used to initialize the application, see configuration
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option :ref:`CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION`.
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The BSP may have knowledge of the specific CPU model, system controller
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logic, and peripheral buses, so a BSP-specific IDLE task may be capable of
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turning components off to save power during extended periods of no task
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activity.
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.. rubric:: CONSTRAINTS:
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The value of the configuration option shall be defined to a valid function
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pointer of the type ``void *( *idle_body )( uintptr_t )``.
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.. Generated from spec:/acfg/if/idle-task-init-appl
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.. raw:: latex
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\clearpage
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.. index:: CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION
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.. _CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION:
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CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION
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-------------------------------------------
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.. rubric:: CONSTANT:
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``CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION``
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.. rubric:: OPTION TYPE:
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This configuration option is a boolean feature define.
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.. rubric:: DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the user is assumed to
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provide one or more initialization tasks.
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.. rubric:: DESCRIPTION:
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This configuration option is defined to indicate that the user has configured
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**no** user initialization tasks or threads and that the user provided IDLE
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task will perform application initialization and then transform itself into
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an IDLE task.
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.. rubric:: NOTES:
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If you use this option be careful, the user IDLE task **cannot** block at all
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during the initialization sequence. Further, once application
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initialization is complete, it shall make itself preemptible and enter an idle
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body loop.
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The IDLE task shall run at the lowest priority of all tasks in the system.
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If this configuration option is defined, then it is mandatory to configure a
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user IDLE task with the :ref:`CONFIGURE_IDLE_TASK_BODY` configuration option,
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otherwise a compile time error in the configuration file will occur.
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The application shall define exactly one of the following configuration
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options
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* :ref:`CONFIGURE_RTEMS_INIT_TASKS_TABLE`,
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* :ref:`CONFIGURE_POSIX_INIT_THREAD_TABLE`, or
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* ``CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION``
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otherwise a compile time error in the configuration file will occur.
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.. Generated from spec:/acfg/if/idle-task-stack-size
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.. raw:: latex
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\clearpage
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.. index:: CONFIGURE_IDLE_TASK_STACK_SIZE
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.. _CONFIGURE_IDLE_TASK_STACK_SIZE:
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CONFIGURE_IDLE_TASK_STACK_SIZE
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------------------------------
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.. rubric:: CONSTANT:
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``CONFIGURE_IDLE_TASK_STACK_SIZE``
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.. rubric:: OPTION TYPE:
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This configuration option is an integer define.
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.. rubric:: DEFAULT VALUE:
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If the :ref:`CONFIGURE_DISABLE_BSP_SETTINGS` configuration option is not defined and
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:c:macro:`BSP_IDLE_TASK_STACK_SIZE` is provided by the
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:term:`BSP`, then the default value is defined by
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:c:macro:`BSP_IDLE_TASK_STACK_SIZE`, otherwise the default value is
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defined by the :ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE` configuration option.
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.. rubric:: DESCRIPTION:
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The value of this configuration option defines the task stack size for an
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IDLE task.
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.. rubric:: NOTES:
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In SMP configurations, there is one IDLE task per configured processor, see
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:ref:`CONFIGURE_MAXIMUM_PROCESSORS`.
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.. rubric:: CONSTRAINTS:
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The following constraints apply to this configuration option:
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* The value of the configuration option shall be greater than or equal to a
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BSP-specific and application-specific minimum value.
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* The value of the configuration option shall be small enough so that the IDLE
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task stack area calculation carried out by ``<rtems/confdefs.h>`` does not
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overflow an integer of type `size_t
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<https://en.cppreference.com/w/c/types/size_t>`_.
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.. Generated from spec:/acfg/if/idle-task-storage-size
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.. raw:: latex
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\clearpage
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.. index:: CONFIGURE_IDLE_TASK_STORAGE_SIZE
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.. index:: IDLE task storage size
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.. _CONFIGURE_IDLE_TASK_STORAGE_SIZE:
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CONFIGURE_IDLE_TASK_STORAGE_SIZE
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--------------------------------
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.. rubric:: CONSTANT:
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``CONFIGURE_IDLE_TASK_STORAGE_SIZE``
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.. rubric:: OPTION TYPE:
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This configuration option is an integer define.
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.. rubric:: DEFAULT VALUE:
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This configuration option has no default value. If it is not specified, then
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the task storage area for each :term:`IDLE task` will allocated
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from the RTEMS Workspace or through a custom IDLE task stack allocator.
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.. rubric:: DESCRIPTION:
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If this configuration option is specified, then the task storage areas for
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the :term:`IDLE tasks <IDLE task>` are statically allocated by
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``<rtems/confdefs.h>``. The value of this configuration option defines the
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size in bytes of the task storage area of each IDLE task in the system.
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.. rubric:: NOTES:
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By default, the IDLE task storage areas are allocated from the RTEMS
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Workspace. Applications which do not want to use a heap allocator can use
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this configuration option to use statically allocated memory for the IDLE
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task storage areas. The task storage area contains the task stack, the
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thread-local storage, and the floating-point context on architectures with a
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separate floating-point context. The size of the thread-local storage area
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is defined at link time or by the :ref:`CONFIGURE_MAXIMUM_THREAD_LOCAL_STORAGE_SIZE`
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configuration option. You have to estimate the actual thread-local storage
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size if you want to use this configuration option. If the IDLE task stack
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size would be less than the value defined by the
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:ref:`CONFIGURE_IDLE_TASK_STACK_SIZE` configuration option, for example because the
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thread-local storage size is larger than expected, then the system terminates
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with the :ref:`INTERNAL_ERROR_CORE <FatalErrorSources>` fatal source and the
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:ref:`INTERNAL_ERROR_IDLE_THREAD_STACK_TOO_SMALL <internal_errors>` fatal code during
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system initialization.
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The value of this configuration option is passed to
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:ref:`InterfaceRTEMSTASKSTORAGESIZE` by ``<rtems/confdefs.h>`` to determine
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the actual size of the statically allocated area to take
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architecture-specific overheads into account.
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The
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* ``CONFIGURE_IDLE_TASK_STORAGE_SIZE``, and
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* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE`
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configuration options are mutually exclusive.
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.. rubric:: CONSTRAINTS:
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The value of the configuration option shall be greater than or equal to
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:ref:`CONFIGURE_IDLE_TASK_STACK_SIZE`.
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