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c-user: Document CONFIGURE_DIRTY_MEMORY

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Close #3843.
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Sebastian Huber 2020-02-10 10:28:49 +01:00
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c-user/configuring_a_system.rst
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@ -425,6 +425,38 @@ General System Configuration
This section defines the general system configuration options supported by
``<rtems/confdefs.h>``.
.. index:: CONFIGURE_DIRTY_MEMORY
.. _CONFIGURE_DIRTY_MEMORY:
CONFIGURE_DIRTY_MEMORY
----------------------
CONSTANT:
``CONFIGURE_DIRTY_MEMORY``
DATA TYPE:
Boolean feature macro.
RANGE:
Defined or undefined.
DEFAULT VALUE:
By default, the memory used by the RTEMS Workspace and the C Program Heap
is uninitialized memory.
DESCRIPTION:
This macro indicates whether RTEMS should dirty the memory used by the
RTEMS Workspace and the C Program Heap as part of its initialization. If
defined, the memory areas are dirtied with a ``0xCF`` byte pattern.
Otherwise, they are not.
NOTES:
Dirtying memory can add significantly to system boot time. It may assist
in finding code that assumes memory starts set to zero. In case
:ref:`CONFIGURE_ZERO_WORKSPACE_AUTOMATICALLY` is also defined, then the
memory is first dirtied and then zeroed.
.. index:: CONFIGURE_EXTRA_TASK_STACKS
.. index:: memory for task tasks
@ -1006,7 +1038,9 @@ DESCRIPTION:
NOTES:
Zeroing memory can add significantly to system boot time. It is not
necessary for RTEMS but is often assumed by support libraries.
necessary for RTEMS but is often assumed by support libraries. In case
:ref:`CONFIGURE_DIRTY_MEMORY` is also defined, then the memory is first
dirtied and then zeroed.
Classic API Configuration
=========================