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This makes it easier to automatically generate parts of the module documentation in the future. Update #3993.
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49 lines
2.0 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-SA-4.0
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.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
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Background
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==========
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.. index:: initialization tasks
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Initialization Tasks
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--------------------
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Initialization task(s) are the mechanism by which RTEMS transfers initial
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control to the user's application. Initialization tasks differ from other
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application tasks in that they are defined in the User Initialization Tasks
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Table and automatically created and started by RTEMS as part of its
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initialization sequence. Since the initialization tasks are scheduled using
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the same algorithm as all other RTEMS tasks, they must be configured at a
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priority and mode which will ensure that they will complete execution before
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other application tasks execute. Although there is no upper limit on the
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number of initialization tasks, an application is required to define at least
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one.
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A typical initialization task will create and start the static set of
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application tasks. It may also create any other objects used by the
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application. Initialization tasks which only perform initialization should
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delete themselves upon completion to free resources for other tasks.
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Initialization tasks may transform themselves into a "normal" application task.
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This transformation typically involves changing priority and execution mode.
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RTEMS does not automatically delete the initialization tasks.
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The Idle Task
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-------------
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The Idle Task is the lowest priority task in a system and executes only when no
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other task is ready to execute. The default implementation of this task
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consists of an infinite loop. RTEMS allows the Idle Task body to be replaced by
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a CPU specific implementation, a BSP specific implementation or an application
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specific implementation.
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The Idle Task is preemptible and *WILL* be preempted when any other task is
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made ready to execute. This characteristic is critical to the overall behavior
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of any application.
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Initialization Manager Failure
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------------------------------
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System initialization errors are fatal. See :ref:`internal_errors`.
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