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Diffstat (limited to '')
| -rw-r--r-- | c-user/config/idle-task.rst | 96 |
1 files changed, 91 insertions, 5 deletions
diff --git a/c-user/config/idle-task.rst b/c-user/config/idle-task.rst index 5cf8364..793fb5c 100644 --- a/c-user/config/idle-task.rst +++ b/c-user/config/idle-task.rst @@ -1,6 +1,6 @@ .. SPDX-License-Identifier: CC-BY-SA-4.0 -.. Copyright (C) 2020, 2021 embedded brains GmbH (http://www.embedded-brains.de) +.. Copyright (C) 2020, 2022 embedded brains GmbH & Co. KG .. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) .. This file is part of the RTEMS quality process and was automatically @@ -48,8 +48,11 @@ This configuration option is an initializer define. .. rubric:: DEFAULT VALUE: -If :ref:`BSP_IDLE_TASK_BODY` is defined, then this will be the default value, -otherwise the default value is ``_CPU_Thread_Idle_body``. +If the :ref:`CONFIGURE_DISABLE_BSP_SETTINGS` configuration option is not defined and +:c:macro:`BSP_IDLE_TASK_BODY` is provided by the +:term:`BSP`, then the default value is defined by +:c:macro:`BSP_IDLE_TASK_BODY`, otherwise the default value is +``_CPU_Thread_Idle_body``. .. rubric:: DESCRIPTION: @@ -64,6 +67,11 @@ exists. IDLE threads can be used to initialize the application, see configuration option :ref:`CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION`. +The BSP may have knowledge of the specific CPU model, system controller +logic, and peripheral buses, so a BSP-specific IDLE task may be capable of +turning components off to save power during extended periods of no task +activity. + .. rubric:: CONSTRAINTS: The value of the configuration option shall be defined to a valid function @@ -115,7 +123,7 @@ If this configuration option is defined, then it is mandatory to configure a user IDLE task with the :ref:`CONFIGURE_IDLE_TASK_BODY` configuration option, otherwise a compile time error in the configuration file will occur. -The application shall define exactly one of the following configuration +The application shall define at least one of the following configuration options * :ref:`CONFIGURE_RTEMS_INIT_TASKS_TABLE`, @@ -126,6 +134,9 @@ options otherwise a compile time error in the configuration file will occur. +If no Classic API initialization task and no POSIX API initialization thread +is configured, then no :ref:`GlobalConstruction` is performed. + .. Generated from spec:/acfg/if/idle-task-stack-size .. raw:: latex @@ -149,7 +160,11 @@ This configuration option is an integer define. .. rubric:: DEFAULT VALUE: -The default value is :ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE`. +If the :ref:`CONFIGURE_DISABLE_BSP_SETTINGS` configuration option is not defined and +:c:macro:`BSP_IDLE_TASK_STACK_SIZE` is provided by the +:term:`BSP`, then the default value is defined by +:c:macro:`BSP_IDLE_TASK_STACK_SIZE`, otherwise the default value is +defined by the :ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE` configuration option. .. rubric:: DESCRIPTION: @@ -172,3 +187,74 @@ The following constraints apply to this configuration option: task stack area calculation carried out by ``<rtems/confdefs.h>`` does not overflow an integer of type `size_t <https://en.cppreference.com/w/c/types/size_t>`_. + +.. Generated from spec:/acfg/if/idle-task-storage-size + +.. raw:: latex + + \clearpage + +.. index:: CONFIGURE_IDLE_TASK_STORAGE_SIZE +.. index:: IDLE task storage size + +.. _CONFIGURE_IDLE_TASK_STORAGE_SIZE: + +CONFIGURE_IDLE_TASK_STORAGE_SIZE +-------------------------------- + +.. rubric:: CONSTANT: + +``CONFIGURE_IDLE_TASK_STORAGE_SIZE`` + +.. rubric:: OPTION TYPE: + +This configuration option is an integer define. + +.. rubric:: DEFAULT VALUE: + +This configuration option has no default value. If it is not specified, then +the task storage area for each :term:`IDLE task` will allocated +from the RTEMS Workspace or through a custom IDLE task stack allocator. + +.. rubric:: DESCRIPTION: + +If this configuration option is specified, then the task storage areas for +the :term:`IDLE tasks <IDLE task>` are statically allocated by +``<rtems/confdefs.h>``. The value of this configuration option defines the +size in bytes of the task storage area of each IDLE task in the system. + +.. rubric:: NOTES: + +By default, the IDLE task storage areas are allocated from the RTEMS +Workspace. Applications which do not want to use a heap allocator can use +this configuration option to use statically allocated memory for the IDLE +task storage areas. The task storage area contains the task stack, the +thread-local storage, and the floating-point context on architectures with a +separate floating-point context. The size of the thread-local storage area +is defined at link time or by the :ref:`CONFIGURE_MAXIMUM_THREAD_LOCAL_STORAGE_SIZE` +configuration option. You have to estimate the actual thread-local storage +size if you want to use this configuration option. If the IDLE task stack +size would be less than the value defined by the +:ref:`CONFIGURE_IDLE_TASK_STACK_SIZE` configuration option, for example because the +thread-local storage size is larger than expected, then the system terminates +with the :ref:`INTERNAL_ERROR_CORE <FatalErrorSources>` fatal source and the +:ref:`INTERNAL_ERROR_IDLE_THREAD_STACK_TOO_SMALL <internal_errors>` fatal code during +system initialization. + +The value of this configuration option is passed to +:ref:`InterfaceRTEMSTASKSTORAGESIZE` by ``<rtems/confdefs.h>`` to determine +the actual size of the statically allocated area to take +architecture-specific overheads into account. + +The + +* ``CONFIGURE_IDLE_TASK_STORAGE_SIZE``, and + +* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE` + +configuration options are mutually exclusive. + +.. rubric:: CONSTRAINTS: + +The value of the configuration option shall be greater than or equal to +:ref:`CONFIGURE_IDLE_TASK_STACK_SIZE`. |