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This makes it easier to automatically generate parts of the manager documentation in the future. Update #3993.
51 lines
1.9 KiB
ReStructuredText
51 lines
1.9 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:: partition, definition
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Partition Manager Definitions
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-----------------------------
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A partition is a physically contiguous memory area divided into fixed-size
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buffers that can be dynamically allocated and deallocated.
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.. index:: buffers, definition
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Partitions are managed and maintained as a list of buffers. Buffers are
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obtained from the front of the partition's free buffer chain and returned to
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the rear of the same chain. When a buffer is on the free buffer chain, RTEMS
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uses two pointers of memory from each buffer as the free buffer chain. When a
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buffer is allocated, the entire buffer is available for application use.
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Therefore, modifying memory that is outside of an allocated buffer could
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destroy the free buffer chain or the contents of an adjacent allocated buffer.
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.. index:: partition attribute set, building
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Building a Partition Attribute Set
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----------------------------------
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In general, an attribute set is built by a bitwise OR of the desired attribute
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components. The set of valid partition attributes is provided in the following
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table:
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.. list-table::
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:class: rtems-table
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* - ``RTEMS_LOCAL``
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- local partition (default)
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* - ``RTEMS_GLOBAL``
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- global partition
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Attribute values are specifically designed to be mutually exclusive, therefore
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bitwise OR and addition operations are equivalent as long as each attribute
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appears exactly once in the component list. An attribute listed as a default
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is not required to appear in the attribute list, although it is a good
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programming practice to specify default attributes. If all defaults are
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desired, the attribute ``RTEMS_DEFAULT_ATTRIBUTES`` should be specified on this
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call. The attribute_set parameter should be ``RTEMS_GLOBAL`` to indicate that
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the partition is to be known globally.
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