rtems/rtems-docs
1
0
Fork 0
mirror of https://git.rtems.org/rtems-docs/ synced 2025-05-14 19:29:44 +08:00
Code Issues Packages Projects Releases Wiki Activity

c-user: Move basic system configuration

Browse Source 
Move the basic system configuration to the front.  Rename it to "General
System Configuration".

Update #3836.
This commit is contained in:
Sebastian Huber 2019-12-10 13:49:52 +01:00
parent f0864b3835
commit bc9ce6526b
1 changed files with 443 additions and 443 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

886
c-user/configuring_a_system.rst
View File

@ -476,6 +476,449 @@ NOTES:
#define CONFIGURE_UNLIMITED_OBJECTS #define CONFIGURE_UNLIMITED_OBJECTS
#define CONFIGURE_UNLIMITED_ALLOCATION_SIZE 5 #define CONFIGURE_UNLIMITED_ALLOCATION_SIZE 5
General System Configuration
============================
This section defines the general system configuration options supported by
``<rtems/confdefs.h>``.
.. index:: CONFIGURE_EXTRA_TASK_STACKS
.. index:: memory for task tasks
.. _CONFIGURE_EXTRA_TASK_STACKS:
CONFIGURE_EXTRA_TASK_STACKS
---------------------------
CONSTANT:
``CONFIGURE_EXTRA_TASK_STACKS``
DATA TYPE:
Unsigned integer (``size_t``).
RANGE:
Undefined or positive.
DEFAULT VALUE:
The default value is 0.
DESCRIPTION:
This configuration parameter is set to the number of bytes the applications
wishes to add to the task stack requirements calculated by
``<rtems/confdefs.h>``.
NOTES:
This parameter is very important. If the application creates tasks with
stacks larger then the minimum, then that memory is NOT accounted for by
``<rtems/confdefs.h>``.
.. index:: CONFIGURE_INITIAL_EXTENSIONS
.. _CONFIGURE_INITIAL_EXTENSIONS:
CONFIGURE_INITIAL_EXTENSIONS
----------------------------
CONSTANT:
``CONFIGURE_INITIAL_EXTENSIONS``
DATA TYPE:
List of user extension initializers (``rtems_extensions_table``).
RANGE:
Undefined or a list of one or more user extensions.
DEFAULT VALUE:
This is not defined by default.
DESCRIPTION:
If ``CONFIGURE_INITIAL_EXTENSIONS`` is defined by the application, then
this application specific set of initial extensions will be placed in the
initial extension table.
NOTES:
None.
.. index:: CONFIGURE_INTERRUPT_STACK_SIZE
.. index:: interrupt stack size
.. _CONFIGURE_INTERRUPT_STACK_SIZE:
CONFIGURE_INTERRUPT_STACK_SIZE
------------------------------
CONSTANT:
``CONFIGURE_INTERRUPT_STACK_SIZE``
DATA TYPE:
Unsigned integer.
RANGE:
Positive.
DEFAULT VALUE:
The default value is ``BSP_INTERRUPT_STACK_SIZE`` in case it is defined,
otherwise the default value is ``CPU_STACK_MINIMUM_SIZE``.
DESCRIPTION:
The ``CONFIGURE_INTERRUPT_STACK_SIZE`` configuration option defines the
size of an interrupt stack in bytes.
NOTES:
The interrupt stack size must be aligned according to
``CPU_INTERRUPT_STACK_ALIGNMENT``.
There is one interrupt stack available for each configured processor
(:ref:`CONFIGURE_MAXIMUM_PROCESSORS <CONFIGURE_MAXIMUM_PROCESSORS>`). The
interrupt stack areas are statically allocated in a special linker section
(``.rtemsstack.interrupt``). The placement of this linker section is
BSP-specific.
Some BSPs use the interrupt stack as the initialization stack which is used
to perform the sequential system initialization before the multithreading
is started.
The interrupt stacks are covered by the :ref:`stack checker
<CONFIGURE_STACK_CHECKER_ENABLED>`. However, using a too small interrupt
stack size may still result in undefined behaviour.
In releases before RTEMS 5.1 the default value was
:ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE
<CONFIGURE_MINIMUM_TASK_STACK_SIZE>` instead of ``CPU_STACK_MINIMUM_SIZE``.
.. index:: CONFIGURE_MAXIMUM_PRIORITY
.. index:: maximum priority
.. index:: number of priority levels
.. _CONFIGURE_MAXIMUM_PRIORITY:
CONFIGURE_MAXIMUM_PRIORITY
--------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_PRIORITY``
DATA TYPE:
Unsigned integer (``uint8_t``).
RANGE:
Valid values for this configuration parameter must be one (1) less than
than a power of two (2) between 4 and 256 inclusively. In other words,
valid values are 3, 7, 31, 63, 127, and 255.
DEFAULT VALUE:
The default value is 255, because RTEMS must support 256 priority levels to
be compliant with various standards. These priorities range from zero (0)
to 255.
DESCRIPTION:
This configuration parameter specified the maximum numeric priority of any
task in the system and one less that the number of priority levels in the
system.
Reducing the number of priorities in the system reduces the amount of memory
allocated from the RTEMS Workspace.
NOTES:
The numerically greatest priority is the logically lowest priority in the
system and will thus be used by the IDLE task.
Priority zero (0) is reserved for internal use by RTEMS and is not available
to applications.
With some schedulers, reducing the number of priorities can reduce the
amount of memory used by the scheduler. For example, the Deterministic
Priority Scheduler (DPS) used by default uses three pointers of storage per
priority level. Reducing the number of priorities from 256 levels to
sixteen (16) can reduce memory usage by about three (3) kilobytes.
.. index:: CONFIGURE_MAXIMUM_PROCESSORS
.. _CONFIGURE_MAXIMUM_PROCESSORS:
CONFIGURE_MAXIMUM_PROCESSORS
----------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_PROCESSORS``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is 1.
DESCRIPTION:
``CONFIGURE_MAXIMUM_PROCESSORS`` must be set to the maximum number of
processors an application intends to use. The number of actually available
processors depends on the hardware and may be less. It is recommended to
use the smallest value suitable for the application in order to save
memory. Each processor needs an idle thread and interrupt stack for
example.
NOTES:
If there are more processors available than configured, the rest will be
ignored. This configuration define is ignored in uniprocessor
configurations.
.. index:: CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
.. index:: maximum thread name size
.. _CONFIGURE_MAXIMUM_THREAD_NAME_SIZE:
CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
----------------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_THREAD_NAME_SIZE``
DATA TYPE:
Unsigned integer (``size_t``).
RANGE:
No restrictions.
DEFAULT VALUE:
The default value is 16. This value was chosen for Linux compatibility,
see
`PTHREAD_SETNAME_NP(3) <http://man7.org/linux/man-pages/man3/pthread_setname_np.3.html>`_.
DESCRIPTION:
This configuration parameter specifies the maximum thread name size
including the terminating `NUL` character.
NOTE:
The size of the thread control block is increased by the maximum thread name
size. This configuration option is available since RTEMS 5.1.
.. index:: CONFIGURE_MICROSECONDS_PER_TICK
.. index:: tick quantum
.. _CONFIGURE_MICROSECONDS_PER_TICK:
CONFIGURE_MICROSECONDS_PER_TICK
-------------------------------
CONSTANT:
``CONFIGURE_MICROSECONDS_PER_TICK``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
This is not defined by default. When not defined, the clock tick quantum is
configured to be 10,000 microseconds which is ten (10) milliseconds.
DESCRIPTION:
This constant is used to specify the length of time between clock ticks.
When the clock tick quantum value is too low, the system will spend so much
time processing clock ticks that it does not have processing time available
to perform application work. In this case, the system will become
unresponsive.
The lowest practical time quantum varies widely based upon the speed of the
target hardware and the architectural overhead associated with
interrupts. In general terms, you do not want to configure it lower than is
needed for the application.
The clock tick quantum should be selected such that it all blocking and
delay times in the application are evenly divisible by it. Otherwise,
rounding errors will be introduced which may negatively impact the
application.
NOTES:
This configuration parameter has no impact if the Clock Tick Device driver
is not configured.
There may be BSP specific limits on the resolution or maximum value of a
clock tick quantum.
.. index:: CONFIGURE_MINIMUM_TASK_STACK_SIZE
.. index:: minimum task stack size
.. _CONFIGURE_MINIMUM_TASK_STACK_SIZE:
CONFIGURE_MINIMUM_TASK_STACK_SIZE
---------------------------------
CONSTANT:
``CONFIGURE_MINIMUM_TASK_STACK_SIZE``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is architecture-specific.
DESCRIPTION:
This configuration parameter defines the minimum stack size in bytes for
every user task or thread in the system.
NOTES:
Adjusting this parameter should be done with caution. Examining the actual
stack usage using the stack checker usage reporting facility is recommended
(see also :ref:`CONFIGURE_STACK_CHECKER_ENABLED <CONFIGURE_STACK_CHECKER_ENABLED>`).
This parameter can be used to lower the minimum from that recommended. This
can be used in low memory systems to reduce memory consumption for
stacks. However, this must be done with caution as it could increase the
possibility of a blown task stack.
This parameter can be used to increase the minimum from that
recommended. This can be used in higher memory systems to reduce the risk
of stack overflow without performing analysis on actual consumption.
By default, this configuration parameter defines also the minimum stack
size of POSIX threads. This can be changed with the
:ref:`CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE <CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE>`
configuration option.
In releases before RTEMS 5.1 the ``CONFIGURE_MINIMUM_TASK_STACK_SIZE`` was
used to define the default value of :ref:`CONFIGURE_INTERRUPT_STACK_SIZE
<CONFIGURE_INTERRUPT_STACK_SIZE>`.
.. index:: CONFIGURE_STACK_CHECKER_ENABLED
.. _CONFIGURE_STACK_CHECKER_ENABLED:
CONFIGURE_STACK_CHECKER_ENABLED
-------------------------------
CONSTANT:
``CONFIGURE_STACK_CHECKER_ENABLED``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, and thus stack checking is disabled.
DESCRIPTION:
This configuration parameter is defined when the application wishes to
enable run-time stack bounds checking.
NOTES:
In 4.9 and older, this configuration parameter was named ``STACK_CHECKER_ON``.
This increases the time required to create tasks as well as adding overhead
to each context switch.
.. index:: CONFIGURE_TICKS_PER_TIMESLICE
.. index:: ticks per timeslice
.. _CONFIGURE_TICKS_PER_TIMESLICE:
CONFIGURE_TICKS_PER_TIMESLICE
-----------------------------
CONSTANT:
``CONFIGURE_TICKS_PER_TIMESLICE``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is 50.
DESCRIPTION:
This configuration parameter specifies the length of the timeslice quantum
in ticks for each task.
NOTES:
This configuration parameter has no impact if the Clock Tick Device driver
is not configured.
.. index:: CONFIGURE_UNIFIED_WORK_AREAS
.. index:: unified work areas
.. index:: separate work areas
.. index:: RTEMS Workspace
.. index:: C Program Heap
.. _CONFIGURE_UNIFIED_WORK_AREAS:
CONFIGURE_UNIFIED_WORK_AREAS
----------------------------
CONSTANT:
``CONFIGURE_UNIFIED_WORK_AREAS``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, which specifies that the C Program Heap and
the RTEMS Workspace will be separate.
DESCRIPTION:
When defined, the C Program Heap and the RTEMS Workspace will be one pool
of memory.
When not defined, there will be separate memory pools for the RTEMS
Workspace and C Program Heap.
NOTES:
Having separate pools does have some advantages in the event a task blows a
stack or writes outside its memory area. However, in low memory systems the
overhead of the two pools plus the potential for unused memory in either
pool is very undesirable.
In high memory environments, this is desirable when you want to use the
RTEMS "unlimited" objects option. You will be able to create objects until
you run out of all available memory rather then just until you run out of
RTEMS Workspace.
.. index:: CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
.. index:: clear C Program Heap
.. index:: clear RTEMS Workspace
.. index:: zero C Program Heap
.. index:: zero RTEMS Workspace
.. _CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY:
CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
--------------------------------------
CONSTANT:
``CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, unless overridden by the BSP. The default
is *NOT* to zero out the RTEMS Workspace or C Program Heap.
DESCRIPTION:
This macro indicates whether RTEMS should zero the RTEMS Workspace and C
Program Heap as part of its initialization. If defined, the memory regions
are zeroed. Otherwise, they are not.
NOTES:
Zeroing memory can add significantly to system boot time. It is not
necessary for RTEMS but is often assumed by support libraries.
Classic API Configuration Classic API Configuration
========================= =========================
@ -1426,449 +1869,6 @@ NOTES:
This is a seldom used configuration parameter. The most likely use case is This is a seldom used configuration parameter. The most likely use case is
when an application desires to have more than one initialization task. when an application desires to have more than one initialization task.
Basic System Information
========================
This section defines the general system configuration parameters supported by
``<rtems/confdefs.h>``.
.. index:: CONFIGURE_UNIFIED_WORK_AREAS
.. index:: unified work areas
.. index:: separate work areas
.. index:: RTEMS Workspace
.. index:: C Program Heap
.. _CONFIGURE_UNIFIED_WORK_AREAS:
CONFIGURE_UNIFIED_WORK_AREAS
----------------------------
CONSTANT:
``CONFIGURE_UNIFIED_WORK_AREAS``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, which specifies that the C Program Heap and
the RTEMS Workspace will be separate.
DESCRIPTION:
When defined, the C Program Heap and the RTEMS Workspace will be one pool
of memory.
When not defined, there will be separate memory pools for the RTEMS
Workspace and C Program Heap.
NOTES:
Having separate pools does have some advantages in the event a task blows a
stack or writes outside its memory area. However, in low memory systems the
overhead of the two pools plus the potential for unused memory in either
pool is very undesirable.
In high memory environments, this is desirable when you want to use the
RTEMS "unlimited" objects option. You will be able to create objects until
you run out of all available memory rather then just until you run out of
RTEMS Workspace.
.. index:: CONFIGURE_MAXIMUM_PROCESSORS
.. _CONFIGURE_MAXIMUM_PROCESSORS:
CONFIGURE_MAXIMUM_PROCESSORS
----------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_PROCESSORS``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is 1.
DESCRIPTION:
``CONFIGURE_MAXIMUM_PROCESSORS`` must be set to the maximum number of
processors an application intends to use. The number of actually available
processors depends on the hardware and may be less. It is recommended to
use the smallest value suitable for the application in order to save
memory. Each processor needs an idle thread and interrupt stack for
example.
NOTES:
If there are more processors available than configured, the rest will be
ignored. This configuration define is ignored in uniprocessor
configurations.
.. index:: CONFIGURE_MICROSECONDS_PER_TICK
.. index:: tick quantum
.. _CONFIGURE_MICROSECONDS_PER_TICK:
CONFIGURE_MICROSECONDS_PER_TICK
-------------------------------
CONSTANT:
``CONFIGURE_MICROSECONDS_PER_TICK``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
This is not defined by default. When not defined, the clock tick quantum is
configured to be 10,000 microseconds which is ten (10) milliseconds.
DESCRIPTION:
This constant is used to specify the length of time between clock ticks.
When the clock tick quantum value is too low, the system will spend so much
time processing clock ticks that it does not have processing time available
to perform application work. In this case, the system will become
unresponsive.
The lowest practical time quantum varies widely based upon the speed of the
target hardware and the architectural overhead associated with
interrupts. In general terms, you do not want to configure it lower than is
needed for the application.
The clock tick quantum should be selected such that it all blocking and
delay times in the application are evenly divisible by it. Otherwise,
rounding errors will be introduced which may negatively impact the
application.
NOTES:
This configuration parameter has no impact if the Clock Tick Device driver
is not configured.
There may be BSP specific limits on the resolution or maximum value of a
clock tick quantum.
.. index:: CONFIGURE_TICKS_PER_TIMESLICE
.. index:: ticks per timeslice
.. _CONFIGURE_TICKS_PER_TIMESLICE:
CONFIGURE_TICKS_PER_TIMESLICE
-----------------------------
CONSTANT:
``CONFIGURE_TICKS_PER_TIMESLICE``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is 50.
DESCRIPTION:
This configuration parameter specifies the length of the timeslice quantum
in ticks for each task.
NOTES:
This configuration parameter has no impact if the Clock Tick Device driver
is not configured.
.. index:: CONFIGURE_MAXIMUM_PRIORITY
.. index:: maximum priority
.. index:: number of priority levels
.. _CONFIGURE_MAXIMUM_PRIORITY:
CONFIGURE_MAXIMUM_PRIORITY
--------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_PRIORITY``
DATA TYPE:
Unsigned integer (``uint8_t``).
RANGE:
Valid values for this configuration parameter must be one (1) less than
than a power of two (2) between 4 and 256 inclusively. In other words,
valid values are 3, 7, 31, 63, 127, and 255.
DEFAULT VALUE:
The default value is 255, because RTEMS must support 256 priority levels to
be compliant with various standards. These priorities range from zero (0)
to 255.
DESCRIPTION:
This configuration parameter specified the maximum numeric priority of any
task in the system and one less that the number of priority levels in the
system.
Reducing the number of priorities in the system reduces the amount of memory
allocated from the RTEMS Workspace.
NOTES:
The numerically greatest priority is the logically lowest priority in the
system and will thus be used by the IDLE task.
Priority zero (0) is reserved for internal use by RTEMS and is not available
to applications.
With some schedulers, reducing the number of priorities can reduce the
amount of memory used by the scheduler. For example, the Deterministic
Priority Scheduler (DPS) used by default uses three pointers of storage per
priority level. Reducing the number of priorities from 256 levels to
sixteen (16) can reduce memory usage by about three (3) kilobytes.
.. index:: CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
.. index:: maximum thread name size
.. _CONFIGURE_MAXIMUM_THREAD_NAME_SIZE:
CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
----------------------------------
CONSTANT:
``CONFIGURE_MAXIMUM_THREAD_NAME_SIZE``
DATA TYPE:
Unsigned integer (``size_t``).
RANGE:
No restrictions.
DEFAULT VALUE:
The default value is 16. This value was chosen for Linux compatibility,
see
`PTHREAD_SETNAME_NP(3) <http://man7.org/linux/man-pages/man3/pthread_setname_np.3.html>`_.
DESCRIPTION:
This configuration parameter specifies the maximum thread name size
including the terminating `NUL` character.
NOTE:
The size of the thread control block is increased by the maximum thread name
size. This configuration option is available since RTEMS 5.1.
.. index:: CONFIGURE_MINIMUM_TASK_STACK_SIZE
.. index:: minimum task stack size
.. _CONFIGURE_MINIMUM_TASK_STACK_SIZE:
CONFIGURE_MINIMUM_TASK_STACK_SIZE
---------------------------------
CONSTANT:
``CONFIGURE_MINIMUM_TASK_STACK_SIZE``
DATA TYPE:
Unsigned integer (``uint32_t``).
RANGE:
Positive.
DEFAULT VALUE:
The default value is architecture-specific.
DESCRIPTION:
This configuration parameter defines the minimum stack size in bytes for
every user task or thread in the system.
NOTES:
Adjusting this parameter should be done with caution. Examining the actual
stack usage using the stack checker usage reporting facility is recommended
(see also :ref:`CONFIGURE_STACK_CHECKER_ENABLED <CONFIGURE_STACK_CHECKER_ENABLED>`).
This parameter can be used to lower the minimum from that recommended. This
can be used in low memory systems to reduce memory consumption for
stacks. However, this must be done with caution as it could increase the
possibility of a blown task stack.
This parameter can be used to increase the minimum from that
recommended. This can be used in higher memory systems to reduce the risk
of stack overflow without performing analysis on actual consumption.
By default, this configuration parameter defines also the minimum stack
size of POSIX threads. This can be changed with the
:ref:`CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE <CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE>`
configuration option.
In releases before RTEMS 5.1 the ``CONFIGURE_MINIMUM_TASK_STACK_SIZE`` was
used to define the default value of :ref:`CONFIGURE_INTERRUPT_STACK_SIZE
<CONFIGURE_INTERRUPT_STACK_SIZE>`.
.. index:: CONFIGURE_INTERRUPT_STACK_SIZE
.. index:: interrupt stack size
.. _CONFIGURE_INTERRUPT_STACK_SIZE:
CONFIGURE_INTERRUPT_STACK_SIZE
------------------------------
CONSTANT:
``CONFIGURE_INTERRUPT_STACK_SIZE``
DATA TYPE:
Unsigned integer.
RANGE:
Positive.
DEFAULT VALUE:
The default value is ``BSP_INTERRUPT_STACK_SIZE`` in case it is defined,
otherwise the default value is ``CPU_STACK_MINIMUM_SIZE``.
DESCRIPTION:
The ``CONFIGURE_INTERRUPT_STACK_SIZE`` configuration option defines the
size of an interrupt stack in bytes.
NOTES:
The interrupt stack size must be aligned according to
``CPU_INTERRUPT_STACK_ALIGNMENT``.
There is one interrupt stack available for each configured processor
(:ref:`CONFIGURE_MAXIMUM_PROCESSORS <CONFIGURE_MAXIMUM_PROCESSORS>`). The
interrupt stack areas are statically allocated in a special linker section
(``.rtemsstack.interrupt``). The placement of this linker section is
BSP-specific.
Some BSPs use the interrupt stack as the initialization stack which is used
to perform the sequential system initialization before the multithreading
is started.
The interrupt stacks are covered by the :ref:`stack checker
<CONFIGURE_STACK_CHECKER_ENABLED>`. However, using a too small interrupt
stack size may still result in undefined behaviour.
In releases before RTEMS 5.1 the default value was
:ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE
<CONFIGURE_MINIMUM_TASK_STACK_SIZE>` instead of ``CPU_STACK_MINIMUM_SIZE``.
.. index:: CONFIGURE_EXTRA_TASK_STACKS
.. index:: memory for task tasks
.. _CONFIGURE_EXTRA_TASK_STACKS:
CONFIGURE_EXTRA_TASK_STACKS
---------------------------
CONSTANT:
``CONFIGURE_EXTRA_TASK_STACKS``
DATA TYPE:
Unsigned integer (``size_t``).
RANGE:
Undefined or positive.
DEFAULT VALUE:
The default value is 0.
DESCRIPTION:
This configuration parameter is set to the number of bytes the applications
wishes to add to the task stack requirements calculated by
``<rtems/confdefs.h>``.
NOTES:
This parameter is very important. If the application creates tasks with
stacks larger then the minimum, then that memory is NOT accounted for by
``<rtems/confdefs.h>``.
.. index:: CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
.. index:: clear C Program Heap
.. index:: clear RTEMS Workspace
.. index:: zero C Program Heap
.. index:: zero RTEMS Workspace
.. _CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY:
CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
--------------------------------------
CONSTANT:
``CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, unless overridden by the BSP. The default
is *NOT* to zero out the RTEMS Workspace or C Program Heap.
DESCRIPTION:
This macro indicates whether RTEMS should zero the RTEMS Workspace and C
Program Heap as part of its initialization. If defined, the memory regions
are zeroed. Otherwise, they are not.
NOTES:
Zeroing memory can add significantly to system boot time. It is not
necessary for RTEMS but is often assumed by support libraries.
.. index:: CONFIGURE_STACK_CHECKER_ENABLED
.. _CONFIGURE_STACK_CHECKER_ENABLED:
CONFIGURE_STACK_CHECKER_ENABLED
-------------------------------
CONSTANT:
``CONFIGURE_STACK_CHECKER_ENABLED``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
This is not defined by default, and thus stack checking is disabled.
DESCRIPTION:
This configuration parameter is defined when the application wishes to
enable run-time stack bounds checking.
NOTES:
In 4.9 and older, this configuration parameter was named ``STACK_CHECKER_ON``.
This increases the time required to create tasks as well as adding overhead
to each context switch.
.. index:: CONFIGURE_INITIAL_EXTENSIONS
.. _CONFIGURE_INITIAL_EXTENSIONS:
CONFIGURE_INITIAL_EXTENSIONS
----------------------------
CONSTANT:
``CONFIGURE_INITIAL_EXTENSIONS``
DATA TYPE:
List of user extension initializers (``rtems_extensions_table``).
RANGE:
Undefined or a list of one or more user extensions.
DEFAULT VALUE:
This is not defined by default.
DESCRIPTION:
If ``CONFIGURE_INITIAL_EXTENSIONS`` is defined by the application, then
this application specific set of initial extensions will be placed in the
initial extension table.
NOTES:
None.
Configuring Custom Task Stack Allocation Configuring Custom Task Stack Allocation
======================================== ========================================