source: rtems-docs/c-user/config/general.rst @ c95e3e3

5
Last change on this file since c95e3e3 was c95e3e3, checked in by Sebastian Huber <sebastian.huber@…>, on 04/01/20 at 07:02:33

c-user: Move CONFIGURE_MAXIMUM_PRIORITY

Move this option to the scheduler configuration options.

Update #3836.
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1.. SPDX-License-Identifier: CC-BY-SA-4.0
2
3.. Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
4.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
5
6General System Configuration
7============================
8
9This section describes general system configuration options.
10
11.. index:: CONFIGURE_DIRTY_MEMORY
12
13.. _CONFIGURE_DIRTY_MEMORY:
14
15CONFIGURE_DIRTY_MEMORY
16----------------------
17
18CONSTANT:
19    ``CONFIGURE_DIRTY_MEMORY``
20
21OPTION TYPE:
22    This configuration option is a boolean feature define.
23
24DEFAULT CONFIGURATION:
25    If this configuration option is undefined, then the described feature is not
26    enabled.
27
28DESCRIPTION:
29    In case this configuration option is defined, then the memory areas used for
30    the RTEMS Workspace and the C Program Heap are dirtied with a ``0xCF`` byte
31    pattern during system initialization.
32
33NOTES:
34    Dirtying memory can add significantly to system initialization time.  It may
35    assist in finding code that incorrectly assumes the contents of free memory
36    areas is cleared to zero during system initialization.  In case
37    :ref:`CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY` is also defined, then the
38    memory is first dirtied and then zeroed.
39
40    See also :ref:`CONFIGURE_MALLOC_DIRTY`.
41
42.. index:: CONFIGURE_DISABLE_NEWLIB_REENTRANCY
43
44.. _CONFIGURE_DISABLE_NEWLIB_REENTRANCY:
45
46CONFIGURE_DISABLE_NEWLIB_REENTRANCY
47-----------------------------------
48
49CONSTANT:
50    ``CONFIGURE_DISABLE_NEWLIB_REENTRANCY``
51
52OPTION TYPE:
53    This configuration option is a boolean feature define.
54
55DEFAULT CONFIGURATION:
56    If this configuration option is undefined, then the described feature is not
57    enabled.
58
59DESCRIPTION:
60    In case this configuration option is defined, then the Newlib reentrancy
61    support per thread is disabled and a global reentrancy structure is used.
62
63NOTES:
64    You can enable this option to reduce the size of the :term:`TCB`.  Use this
65    option with care, since it can lead to race conditions and undefined system
66    behaviour.  For example, :c:data:`errno` is no longer a thread-local variable
67    if this option is enabled.
68
69.. index:: CONFIGURE_EXECUTIVE_RAM_SIZE
70
71.. _CONFIGURE_EXECUTIVE_RAM_SIZE:
72
73CONFIGURE_EXECUTIVE_RAM_SIZE
74----------------------------
75
76CONSTANT:
77    ``CONFIGURE_EXECUTIVE_RAM_SIZE``
78
79OPTION TYPE:
80    This configuration option is an integer define.
81
82DEFAULT VALUE:
83    If this configuration option is undefined, then the RTEMS Workspace and task
84    stack space size is calculated by ``<rtems/confdefs.h>`` based on the values
85    configuration options.
86
87VALUE CONSTRAINTS:
88    The value of this configuration option shall satisfy all of the following
89    constraints:
90
91    * It shall be greater than or equal to 0.
92
93    * It shall be less than or equal to ``UINTPTR_MAX``.
94
95    * It shall be less than or equal to a
96      BSP-specific and application-specific value which depends on the size of the
97      memory available to the application.
98
99DESCRIPTION:
100    The value of this configuration option defines the RTEMS Workspace size in
101    bytes.
102
103NOTES:
104    This is an advanced configuration option.  Use it only if you know exactly
105    what you are doing.
106
107.. index:: CONFIGURE_EXTRA_TASK_STACKS
108.. index:: memory for task tasks
109
110.. _CONFIGURE_EXTRA_TASK_STACKS:
111
112CONFIGURE_EXTRA_TASK_STACKS
113---------------------------
114
115CONSTANT:
116    ``CONFIGURE_EXTRA_TASK_STACKS``
117
118OPTION TYPE:
119    This configuration option is an integer define.
120
121DEFAULT VALUE:
122    The default value is 0.
123
124VALUE CONSTRAINTS:
125    The value of this configuration option shall satisfy all of the following
126    constraints:
127
128    * It shall be greater than or equal to 0.
129
130    * It shall be small enough so that the task
131      stack space calculation carried out by ``<rtems/confdefs.h>`` does not
132      overflow an integer of type ``uintptr_t``.
133
134DESCRIPTION:
135    The value of this configuration option defines the number of bytes the
136    applications wishes to add to the task stack requirements calculated by
137    ``<rtems/confdefs.h>``.
138
139NOTES:
140    This parameter is very important.  If the application creates tasks with
141    stacks larger then the minimum, then that memory is **not** accounted for by
142    ``<rtems/confdefs.h>``.
143
144.. index:: CONFIGURE_INITIAL_EXTENSIONS
145
146.. _CONFIGURE_INITIAL_EXTENSIONS:
147
148CONFIGURE_INITIAL_EXTENSIONS
149----------------------------
150
151CONSTANT:
152    ``CONFIGURE_INITIAL_EXTENSIONS``
153
154OPTION TYPE:
155    This configuration option is an initializer define.
156
157DEFAULT VALUE:
158    The default value is the empty list.
159
160VALUE CONSTRAINTS:
161    The value of this configuration option shall be a list of initializers for
162    structures of type :c:type:`rtems_extensions_table`.
163
164DESCRIPTION:
165    The value of this configuration option is used to initialize the table of
166    initial user extensions.
167
168NOTES:
169    The value of this configuration option is placed before the entries of
170    :ref:`BSP_INITIAL_EXTENSION` and after the entries of all other initial
171    user extensions.
172
173.. index:: CONFIGURE_INTERRUPT_STACK_SIZE
174.. index:: interrupt stack size
175
176.. _CONFIGURE_INTERRUPT_STACK_SIZE:
177
178CONFIGURE_INTERRUPT_STACK_SIZE
179------------------------------
180
181CONSTANT:
182    ``CONFIGURE_INTERRUPT_STACK_SIZE``
183
184OPTION TYPE:
185    This configuration option is an integer define.
186
187DEFAULT VALUE:
188    The default value is :ref:`BSP_INTERRUPT_STACK_SIZE` in case it is defined,
189    otherwise the default value is ``CPU_STACK_MINIMUM_SIZE``.
190
191VALUE CONSTRAINTS:
192    The value of this configuration option shall satisfy all of the following
193    constraints:
194
195    * It shall be greater than or equal to a
196      BSP-specific and application-specific minimum value.
197
198    * It shall be small enough so that the
199      interrupt stack area calculation carried out by ``<rtems/confdefs.h>`` does
200      not overflow an integer of type ``size_t``.
201
202    * It shall be aligned according to
203      ``CPU_INTERRUPT_STACK_ALIGNMENT``.
204
205DESCRIPTION:
206    The value of this configuration option defines the size of an interrupt stack
207    in bytes.
208
209NOTES:
210    There is one interrupt stack available for each configured processor
211    (:ref:`CONFIGURE_MAXIMUM_PROCESSORS`).  The interrupt stack areas are
212    statically allocated in a special linker section (``.rtemsstack.interrupt``).
213    The placement of this linker section is BSP-specific.
214
215    Some BSPs use the interrupt stack as the initialization stack which is used
216    to perform the sequential system initialization before the multithreading
217    is started.
218
219    The interrupt stacks are covered by the :ref:`stack checker
220    <CONFIGURE_STACK_CHECKER_ENABLED>`.  However, using a too small interrupt
221    stack size may still result in undefined behaviour.
222
223    In releases before RTEMS 5.1 the default value was
224    :ref:`CONFIGURE_MINIMUM_TASK_STACK_SIZE` instead of ``CPU_STACK_MINIMUM_SIZE``.
225
226.. index:: CONFIGURE_MALLOC_DIRTY
227
228.. _CONFIGURE_MALLOC_DIRTY:
229
230CONFIGURE_MALLOC_DIRTY
231----------------------
232
233CONSTANT:
234    ``CONFIGURE_MALLOC_DIRTY``
235
236OPTION TYPE:
237    This configuration option is a boolean feature define.
238
239DEFAULT CONFIGURATION:
240    If this configuration option is undefined, then the described feature is not
241    enabled.
242
243DESCRIPTION:
244    In case this configuration option is defined, then each memory area returned
245    by C Program Heap allocator functions such as :c:func:`malloc` is dirtied
246    with a ``0xCF`` byte pattern before it is handed over to the application.
247
248NOTES:
249    The dirtying performed by this option is carried out for each successful
250    memory allocation from the C Program Heap in contrast to
251    :ref:`CONFIGURE_DIRTY_MEMORY` which dirties the memory only once during the
252    system initialization.
253
254.. index:: CONFIGURE_MAXIMUM_FILE_DESCRIPTORS
255.. index:: maximum file descriptors
256
257.. _CONFIGURE_MAXIMUM_FILE_DESCRIPTORS:
258
259CONFIGURE_MAXIMUM_FILE_DESCRIPTORS
260----------------------------------
261
262CONSTANT:
263    ``CONFIGURE_MAXIMUM_FILE_DESCRIPTORS``
264
265OPTION TYPE:
266    This configuration option is an integer define.
267
268DEFAULT VALUE:
269    The default value is 3.
270
271VALUE CONSTRAINTS:
272    The value of this configuration option shall satisfy all of the following
273    constraints:
274
275    * It shall be greater than or equal to 0.
276
277    * It shall be less than or equal to ``SIZE_MAX``.
278
279    * It shall be less than or equal to a
280      BSP-specific and application-specific value which depends on the size of the
281      memory available to the application.
282
283DESCRIPTION:
284    The value of this configuration option defines the maximum number of file
285    like objects that can be concurrently open.
286
287NOTES:
288    The default value of three file descriptors allows RTEMS to support standard
289    input, output, and error I/O streams on ``/dev/console``.
290
291.. index:: CONFIGURE_MAXIMUM_PROCESSORS
292
293.. _CONFIGURE_MAXIMUM_PROCESSORS:
294
295CONFIGURE_MAXIMUM_PROCESSORS
296----------------------------
297
298CONSTANT:
299    ``CONFIGURE_MAXIMUM_PROCESSORS``
300
301OPTION TYPE:
302    This configuration option is an integer define.
303
304DEFAULT VALUE:
305    The default value is 1.
306
307VALUE CONSTRAINTS:
308    The value of this configuration option shall be greater than or equal to 0
309    and less than or equal to ``CPU_MAXIMUM_PROCESSORS``.
310
311DESCRIPTION:
312    The value of this configuration option defines the maximum number of
313    processors an application intends to use.  The number of actually available
314    processors depends on the hardware and may be less.  It is recommended to use
315    the smallest value suitable for the application in order to save memory.
316    Each processor needs an IDLE task stack and interrupt stack for example.
317
318NOTES:
319    If there are more processors available than configured, the rest will be
320    ignored.
321
322    This configuration option is only evaluated in SMP configurations (e.g. RTEMS
323    was built with the ``--enable-smp`` build configuration option).  In all
324    other configurations it has no effect.
325
326.. index:: CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
327.. index:: maximum thread name size
328
329.. _CONFIGURE_MAXIMUM_THREAD_NAME_SIZE:
330
331CONFIGURE_MAXIMUM_THREAD_NAME_SIZE
332----------------------------------
333
334CONSTANT:
335    ``CONFIGURE_MAXIMUM_THREAD_NAME_SIZE``
336
337OPTION TYPE:
338    This configuration option is an integer define.
339
340DEFAULT VALUE:
341    The default value is 16.
342
343VALUE CONSTRAINTS:
344    The value of this configuration option shall satisfy all of the following
345    constraints:
346
347    * It shall be greater than or equal to 0.
348
349    * It shall be less than or equal to ``SIZE_MAX``.
350
351    * It shall be less than or equal to a
352      BSP-specific and application-specific value which depends on the size of the
353      memory available to the application.
354
355DESCRIPTION:
356    The value of this configuration option defines the maximum thread name size
357    including the terminating ``NUL`` character.
358
359NOTES:
360    The default value was chosen for Linux compatibility, see
361    `PTHREAD_SETNAME_NP(3) <http://man7.org/linux/man-pages/man3/pthread_setname_np.3.html>`_.
362
363    The size of the thread control block is increased by the maximum thread name
364    size.
365
366    This configuration option is available since RTEMS 5.1.
367
368.. index:: CONFIGURE_MEMORY_OVERHEAD
369
370.. _CONFIGURE_MEMORY_OVERHEAD:
371
372CONFIGURE_MEMORY_OVERHEAD
373-------------------------
374
375CONSTANT:
376    ``CONFIGURE_MEMORY_OVERHEAD``
377
378OPTION TYPE:
379    This configuration option is an integer define.
380
381DEFAULT VALUE:
382    The default value is 0.
383
384VALUE CONSTRAINTS:
385    The value of this configuration option shall satisfy all of the following
386    constraints:
387
388    * It shall be greater than or equal to 0.
389
390    * It shall be less than or equal to a
391      BSP-specific and application-specific value which depends on the size of the
392      memory available to the application.
393
394    * It shall be small enough so that the
395      RTEMS Workspace size calculation carried out by ``<rtems/confdefs.h>`` does
396      not overflow an integer of type ``uintptr_t``.
397
398DESCRIPTION:
399    The value of this configuration option defines the number of kilobytes the
400    application wishes to add to the RTEMS Workspace size calculated by
401    ``<rtems/confdefs.h>``.
402
403NOTES:
404    This configuration option should only be used when it is suspected that a bug
405    in ``<rtems/confdefs.h>`` has resulted in an underestimation.  Typically the
406    memory allocation will be too low when an application does not account for
407    all message queue buffers or task stacks, see
408    :ref:`CONFIGURE_MESSAGE_BUFFER_MEMORY`.
409
410.. index:: CONFIGURE_MESSAGE_BUFFER_MEMORY
411.. index:: configure message queue buffer memory
412.. index:: CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE
413.. index:: memory for a single message queue's buffers
414
415.. _CONFIGURE_MESSAGE_BUFFER_MEMORY:
416
417CONFIGURE_MESSAGE_BUFFER_MEMORY
418-------------------------------
419
420CONSTANT:
421    ``CONFIGURE_MESSAGE_BUFFER_MEMORY``
422
423OPTION TYPE:
424    This configuration option is an integer define.
425
426DEFAULT VALUE:
427    The default value is 0.
428
429VALUE CONSTRAINTS:
430    The value of this configuration option shall satisfy all of the following
431    constraints:
432
433    * It shall be greater than or equal to 0.
434
435    * It shall be less than or equal to a
436      BSP-specific and application-specific value which depends on the size of the
437      memory available to the application.
438
439    * It shall be small enough so that the
440      RTEMS Workspace size calculation carried out by ``<rtems/confdefs.h>`` does
441      not overflow an integer of type ``uintptr_t``.
442
443DESCRIPTION:
444    The value of this configuration option defines the number of bytes reserved
445    for message queue buffers in the RTEMS Workspace.
446
447NOTES:
448    The configuration options :ref:`CONFIGURE_MAXIMUM_MESSAGE_QUEUES` and
449    :ref:`CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES` define only how many message
450    queues can be created by the application.  The memory for the message
451    buffers is configured by this option.  For each message queue you have to
452    reserve some memory for the message buffers.  The size dependes on the
453    maximum number of pending messages and the maximum size of the messages of
454    a message queue.  Use the ``CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE()`` macro
455    to specify the message buffer memory for each message queue and sum them up
456    to define the value for ``CONFIGURE_MAXIMUM_MESSAGE_QUEUES``.
457
458    The interface for the ``CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE()`` help
459    macro is as follows:
460
461    .. code-block:: c
462
463        CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE( max_messages, max_msg_size )
464
465    Where ``max_messages`` is the maximum number of pending messages and
466    ``max_msg_size`` is the maximum size in bytes of the messages of the
467    corresponding message queue.  Both parameters shall be compile time
468    constants.  Not using this help macro (e.g. just using
469    ``max_messages * max_msg_size``) may result in an underestimate of the
470    RTEMS Workspace size.
471
472    The following example illustrates how the
473    `CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE()` help macro can be used to assist in
474    calculating the message buffer memory required.  In this example, there are
475    two message queues used in this application.  The first message queue has a
476    maximum of 24 pending messages with the message structure defined by the
477    type ``one_message_type``.  The other message queue has a maximum of 500
478    pending messages with the message structure defined by the type
479    ``other_message_type``.
480
481    .. code-block:: c
482
483        #define CONFIGURE_MESSAGE_BUFFER_MEMORY ( \
484            CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE( \
485              24, \
486              sizeof( one_message_type ) \
487            ) \
488            + CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE( \
489              500, \
490              sizeof( other_message_type ) \
491            ) \
492          )
493
494.. index:: CONFIGURE_MICROSECONDS_PER_TICK
495.. index:: clock tick quantum
496.. index:: tick quantum
497
498.. _CONFIGURE_MICROSECONDS_PER_TICK:
499
500CONFIGURE_MICROSECONDS_PER_TICK
501-------------------------------
502
503CONSTANT:
504    ``CONFIGURE_MICROSECONDS_PER_TICK``
505
506OPTION TYPE:
507    This configuration option is an integer define.
508
509DEFAULT VALUE:
510    The default value is 10000.
511
512VALUE CONSTRAINTS:
513    The value of this configuration option shall satisfy all of the following
514    constraints:
515
516    * It shall be greater than or equal to a Clock Driver specific value.
517
518    * It shall be less than or equal to a Clock Driver specific value.
519
520    * The resulting clock ticks per second should be an integer.
521
522DESCRIPTION:
523    The value of this configuration option defines the length of time in
524    microseconds between clock ticks (clock tick quantum).
525
526    When the clock tick quantum value is too low, the system will spend so much
527    time processing clock ticks that it does not have processing time available
528    to perform application work. In this case, the system will become
529    unresponsive.
530
531    The lowest practical time quantum varies widely based upon the speed of the
532    target hardware and the architectural overhead associated with
533    interrupts. In general terms, you do not want to configure it lower than is
534    needed for the application.
535
536    The clock tick quantum should be selected such that it all blocking and
537    delay times in the application are evenly divisible by it. Otherwise,
538    rounding errors will be introduced which may negatively impact the
539    application.
540
541NOTES:
542    This configuration option has no impact if the Clock Driver is not
543    configured, see :ref:`CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER`.
544
545    There may be Clock Driver specific limits on the resolution or maximum value
546    of a clock tick quantum.
547
548.. index:: CONFIGURE_MINIMUM_TASK_STACK_SIZE
549.. index:: minimum task stack size
550
551.. _CONFIGURE_MINIMUM_TASK_STACK_SIZE:
552
553CONFIGURE_MINIMUM_TASK_STACK_SIZE
554---------------------------------
555
556CONSTANT:
557    ``CONFIGURE_MINIMUM_TASK_STACK_SIZE``
558
559OPTION TYPE:
560    This configuration option is an integer define.
561
562DEFAULT VALUE:
563    The default value is ``CPU_STACK_MINIMUM_SIZE``.
564
565VALUE CONSTRAINTS:
566    The value of this configuration option shall satisfy all of the following
567    constraints:
568
569    * It shall be small enough so that the task
570      stack space calculation carried out by ``<rtems/confdefs.h>`` does not
571      overflow an integer of type ``uintptr_t``.
572
573    * It shall be greater than or equal to a
574      BSP-specific and application-specific minimum value.
575
576DESCRIPTION:
577    The value of this configuration option defines the minimum stack size in
578    bytes for every user task or thread in the system.
579
580NOTES:
581    Adjusting this parameter should be done with caution.  Examining the actual
582    stack usage using the stack checker usage reporting facility is recommended
583    (see also :ref:`CONFIGURE_STACK_CHECKER_ENABLED`).
584
585    This parameter can be used to lower the minimum from that recommended. This
586    can be used in low memory systems to reduce memory consumption for
587    stacks. However, this shall be done with caution as it could increase the
588    possibility of a blown task stack.
589
590    This parameter can be used to increase the minimum from that
591    recommended. This can be used in higher memory systems to reduce the risk
592    of stack overflow without performing analysis on actual consumption.
593
594    By default, this configuration parameter defines also the minimum stack
595    size of POSIX threads.  This can be changed with the
596    :ref:`CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE`
597    configuration option.
598
599    In releases before RTEMS 5.1 the ``CONFIGURE_MINIMUM_TASK_STACK_SIZE`` was
600    used to define the default value of :ref:`CONFIGURE_INTERRUPT_STACK_SIZE`.
601
602.. index:: CONFIGURE_STACK_CHECKER_ENABLED
603
604.. _CONFIGURE_STACK_CHECKER_ENABLED:
605
606CONFIGURE_STACK_CHECKER_ENABLED
607-------------------------------
608
609CONSTANT:
610    ``CONFIGURE_STACK_CHECKER_ENABLED``
611
612OPTION TYPE:
613    This configuration option is a boolean feature define.
614
615DEFAULT CONFIGURATION:
616    If this configuration option is undefined, then the described feature is not
617    enabled.
618
619DESCRIPTION:
620    In case this configuration option is defined, then the stack checker is
621    enabled.
622
623NOTES:
624    The stack checker performs run-time stack bounds checking.  This increases
625    the time required to create tasks as well as adding overhead to each context
626    switch.
627
628    In 4.9 and older, this configuration option was named ``STACK_CHECKER_ON``.
629
630.. index:: CONFIGURE_TICKS_PER_TIMESLICE
631.. index:: ticks per timeslice
632
633.. _CONFIGURE_TICKS_PER_TIMESLICE:
634
635CONFIGURE_TICKS_PER_TIMESLICE
636-----------------------------
637
638CONSTANT:
639    ``CONFIGURE_TICKS_PER_TIMESLICE``
640
641OPTION TYPE:
642    This configuration option is an integer define.
643
644DEFAULT VALUE:
645    The default value is 50.
646
647VALUE CONSTRAINTS:
648    The value of this configuration option shall be greater than or equal to 0
649    and less than or equal to ``UINT32_MAX``.
650
651DESCRIPTION:
652    The value of this configuration option defines the length of the timeslice
653    quantum in ticks for each task.
654
655NOTES:
656    This configuration option has no impact if the Clock Driver is not
657    configured, see :ref:`CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER`.
658
659.. index:: CONFIGURE_UNIFIED_WORK_AREAS
660.. index:: unified work areas
661.. index:: separate work areas
662.. index:: RTEMS Workspace
663.. index:: C Program Heap
664
665.. _CONFIGURE_UNIFIED_WORK_AREAS:
666
667CONFIGURE_UNIFIED_WORK_AREAS
668----------------------------
669
670CONSTANT:
671    ``CONFIGURE_UNIFIED_WORK_AREAS``
672
673OPTION TYPE:
674    This configuration option is a boolean feature define.
675
676DEFAULT CONFIGURATION:
677    If this configuration option is undefined, then there will be separate memory
678    pools for the RTEMS Workspace and C Program Heap.
679
680DESCRIPTION:
681    In case this configuration option is defined, then the RTEMS Workspace and
682    the C Program Heap will be one pool of memory.
683
684NOTES:
685    Having separate pools does have some advantages in the event a task blows a
686    stack or writes outside its memory area. However, in low memory systems the
687    overhead of the two pools plus the potential for unused memory in either
688    pool is very undesirable.
689
690    In high memory environments, this is desirable when you want to use the
691    :ref:`ConfigUnlimitedObjects` option.  You will be able to create objects
692    until you run out of all available memory rather then just until you run out
693    of RTEMS Workspace.
694
695.. index:: CONFIGURE_UNLIMITED_ALLOCATION_SIZE
696
697.. _CONFIGURE_UNLIMITED_ALLOCATION_SIZE:
698
699CONFIGURE_UNLIMITED_ALLOCATION_SIZE
700-----------------------------------
701
702CONSTANT:
703    ``CONFIGURE_UNLIMITED_ALLOCATION_SIZE``
704
705OPTION TYPE:
706    This configuration option is an integer define.
707
708DEFAULT VALUE:
709    The default value is 8.
710
711VALUE CONSTRAINTS:
712    The value of this configuration option shall meet the constraints of all
713    object classes to which it is applied.
714
715DESCRIPTION:
716    If :ref:`CONFIGURE_UNLIMITED_OBJECTS` is defined, then the value of this
717    configuration option defines the default objects maximum of all object
718    classes supporting :ref:`ConfigUnlimitedObjects` to
719    ``rtems_resource_unlimited(CONFIGURE_UNLIMITED_ALLOCATION_SIZE)``.
720
721NOTES:
722    By allowing users to declare all resources as being unlimited the user can
723    avoid identifying and limiting the resources used.
724
725    The object maximum of each class can be configured also individually using
726    the :c:func:`rtems_resource_unlimited` macro.
727
728.. index:: CONFIGURE_UNLIMITED_OBJECTS
729
730.. _CONFIGURE_UNLIMITED_OBJECTS:
731
732CONFIGURE_UNLIMITED_OBJECTS
733---------------------------
734
735CONSTANT:
736    ``CONFIGURE_UNLIMITED_OBJECTS``
737
738OPTION TYPE:
739    This configuration option is a boolean feature define.
740
741DEFAULT CONFIGURATION:
742    If this configuration option is undefined, then the described feature is not
743    enabled.
744
745DESCRIPTION:
746    In case this configuration option is defined, then unlimited objects are used
747    by default.
748
749NOTES:
750    When using unlimited objects, it is common practice to also specify
751    :ref:`CONFIGURE_UNIFIED_WORK_AREAS` so the system operates with a single pool
752    of memory for both RTEMS Workspace and C Program Heap.
753
754    This option does not override an explicit configuration for a particular
755    object class by the user.
756
757    See also :ref:`CONFIGURE_UNLIMITED_ALLOCATION_SIZE`.
758
759.. index:: CONFIGURE_VERBOSE_SYSTEM_INITIALIZATION
760
761.. _CONFIGURE_VERBOSE_SYSTEM_INITIALIZATION:
762
763CONFIGURE_VERBOSE_SYSTEM_INITIALIZATION
764---------------------------------------
765
766CONSTANT:
767    ``CONFIGURE_VERBOSE_SYSTEM_INITIALIZATION``
768
769OPTION TYPE:
770    This configuration option is a boolean feature define.
771
772DEFAULT CONFIGURATION:
773    If this configuration option is undefined, then the described feature is not
774    enabled.
775
776DESCRIPTION:
777    In case this configuration option is defined, then the system initialization
778    is verbose.
779
780NOTES:
781    You may use this feature to debug system initialization issues.  The
782    :c:func:`printk` function is used to print the information.
783
784.. index:: CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
785.. index:: clear C Program Heap
786.. index:: clear RTEMS Workspace
787.. index:: zero C Program Heap
788.. index:: zero RTEMS Workspace
789
790.. _CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY:
791
792CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY
793--------------------------------------
794
795CONSTANT:
796    ``CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY``
797
798OPTION TYPE:
799    This configuration option is a boolean feature define.
800
801DEFAULT CONFIGURATION:
802    If this configuration option is undefined, then the described feature is not
803    enabled.
804
805DESCRIPTION:
806    In case this configuration option is defined, then the memory areas used for
807    the RTEMS Workspace and the C Program Heap are zeroed with a ``0x00`` byte
808    pattern during system initialization.
809
810NOTES:
811    Zeroing memory can add significantly to the system initialization time. It is
812    not necessary for RTEMS but is often assumed by support libraries.  In case
813    :ref:`CONFIGURE_DIRTY_MEMORY` is also defined, then the memory is first
814    dirtied and then zeroed.
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