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.. SPDX-License-Identifier: CC-BY-SA-4.0
.. Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
.. Copyright (C) 1988, 2008, 2021 On-Line Applications Research Corporation (OAR)
Task Stack Allocator Configuration
==================================
This section describes configuration options related to the task stack
allocator. RTEMS allows the application or BSP to define its own allocation
and deallocation methods for task stacks. This can be used to place task stacks
in special areas of memory or to utilize a Memory Management Unit so that stack
overflows are detected in hardware.
.. index:: CONFIGURE_TASK_STACK_ALLOCATOR
.. index:: task stack allocator
.. _CONFIGURE_TASK_STACK_ALLOCATOR:
CONFIGURE_TASK_STACK_ALLOCATOR
------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_ALLOCATOR``
OPTION TYPE:
This configuration option is an initializer define.
DEFAULT VALUE:
The default value is ``_Workspace_Allocate``, which indicates that task
stacks will be allocated from the RTEMS Workspace.
VALUE CONSTRAINTS:
The value of this configuration option shall be defined to a valid function
pointer of the type ``void *( *allocate )( size_t )``.
DESCRIPTION:
The value of this configuration option initializes the stack allocator
allocate handler.
NOTES:
A correctly configured system shall configure the following to be consistent:
* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR_INIT`
* `CONFIGURE_TASK_STACK_ALLOCATOR`
* :ref:`CONFIGURE_TASK_STACK_DEALLOCATOR`
.. index:: CONFIGURE_TASK_STACK_ALLOCATOR_INIT
.. _CONFIGURE_TASK_STACK_ALLOCATOR_INIT:
CONFIGURE_TASK_STACK_ALLOCATOR_INIT
-----------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_ALLOCATOR_INIT``
OPTION TYPE:
This configuration option is an initializer define.
DEFAULT VALUE:
The default value is ``NULL``.
VALUE CONSTRAINTS:
The value of this configuration option shall be defined to a valid function
pointer of the type ``void ( *initialize )( size_t )`` or to ``NULL``.
DESCRIPTION:
The value of this configuration option initializes the stack allocator
initialization handler.
NOTES:
A correctly configured system shall configure the following to be consistent:
* `CONFIGURE_TASK_STACK_ALLOCATOR_INIT`
* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR`
* :ref:`CONFIGURE_TASK_STACK_DEALLOCATOR`
.. index:: CONFIGURE_TASK_STACK_DEALLOCATOR
.. index:: task stack deallocator
.. _CONFIGURE_TASK_STACK_DEALLOCATOR:
CONFIGURE_TASK_STACK_DEALLOCATOR
--------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_DEALLOCATOR``
OPTION TYPE:
This configuration option is an initializer define.
DEFAULT VALUE:
The default value is ``_Workspace_Free``, which indicates that task stacks
will be allocated from the RTEMS Workspace.
VALUE CONSTRAINTS:
The value of this configuration option shall be defined to a valid function
pointer of the type ``void ( *deallocate )( void * )``.
DESCRIPTION:
The value of this configuration option initializes the stack allocator
deallocate handler.
NOTES:
A correctly configured system shall configure the following to be consistent:
* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR_INIT`
* :ref:`CONFIGURE_TASK_STACK_ALLOCATOR`
* `CONFIGURE_TASK_STACK_DEALLOCATOR`
.. index:: CONFIGURE_TASK_STACK_FROM_ALLOCATOR
.. index:: task stack allocator
.. _CONFIGURE_TASK_STACK_FROM_ALLOCATOR:
CONFIGURE_TASK_STACK_FROM_ALLOCATOR
-----------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_FROM_ALLOCATOR``
OPTION TYPE:
This configuration option is an initializer define.
DEFAULT VALUE:
The default value is a macro which supports the system heap allocator.
VALUE CONSTRAINTS:
The value of this configuration option shall be defined to a macro which
accepts exactly one parameter and returns an unsigned integer. The
parameter will be an allocation size and the macro shall return this size
plus the overhead of the allocator to manage an allocation request for this
size.
DESCRIPTION:
The value of this configuration option is used to calculate the task stack
space size.
NOTES:
This configuration option may be used if a custom task stack allocator is
configured, see :ref:`CONFIGURE_TASK_STACK_ALLOCATOR`.
.. index:: CONFIGURE_TASK_STACK_ALLOCATOR_AVOIDS_WORK_SPACE
.. _CONFIGURE_TASK_STACK_ALLOCATOR_AVOIDS_WORK_SPACE:
CONFIGURE_TASK_STACK_ALLOCATOR_AVOIDS_WORK_SPACE
------------------------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_ALLOCATOR_AVOIDS_WORK_SPACE``
OPTION TYPE:
This configuration option is a boolean feature define.
DEFAULT CONFIGURATION:
If this configuration option is undefined, then the described feature is not
enabled.
DESCRIPTION:
In case this configuration option is defined, then the system is informed
that the task stack allocator does not use the RTEMS Workspace.
NOTES:
This configuration option may be used if a custom task stack allocator is
configured, see :ref:`CONFIGURE_TASK_STACK_ALLOCATOR`.
.. index:: _CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE
.. index:: IDLE task stack allocator
.. _CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE:
CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE
---------------------------------------
CONSTANT:
``CONFIGURE_TASK_STACK_ALLOCATOR_FOR_IDLE``
OPTION TYPE:
This configuration option is an initializer define.
DEFAULT VALUE:
The default value is ``_Stack_Allocator_allocate_for_idle``, which
indicates that IDLE task stacks will be allocated from an area statically
reserved by `<rtems/confdefs.h>``.
VALUE CONSTRAINTS:
The value of this configuration option shall be defined to a valid
function pointer of the type ``void *( *allocate )( uint32_t, size_t )``.
DESCRIPTION:
The value of this configuration option is the address for the the
IDLE stack allocator allocate handler.
NOTES:
This configuration option is independent of the other thread stack allocator
configuration options. It is assumed that any memory allocated for IDLE
task stacks will not be from the RTEMS Workspace or the memory statically
reserved by default.
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