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diff --git a/c-user/region/directives.rst b/c-user/region/directives.rst new file mode 100644 index 0000000..557b89e --- /dev/null +++ b/c-user/region/directives.rst @@ -0,0 +1,916 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 2020, 2021 embedded brains GmbH & Co. KG +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +.. This file is part of the RTEMS quality process and was automatically +.. generated. If you find something that needs to be fixed or +.. worded better please post a report or patch to an RTEMS mailing list +.. or raise a bug report: +.. +.. https://www.rtems.org/bugs.html +.. +.. For information on updating and regenerating please refer to the How-To +.. section in the Software Requirements Engineering chapter of the +.. RTEMS Software Engineering manual. The manual is provided as a part of +.. a release. For development sources please refer to the online +.. documentation at: +.. +.. https://docs.rtems.org + +.. _RegionManagerDirectives: + +Directives +========== + +This section details the directives of the Region Manager. A subsection is +dedicated to each of this manager's directives and lists the calling sequence, +parameters, description, return values, and notes of the directive. + +.. Generated from spec:/rtems/region/if/create + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_create() +.. index:: create a region + +.. _InterfaceRtemsRegionCreate: + +rtems_region_create() +--------------------- + +Creates a region. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_create( + rtems_name name, + void *starting_address, + uintptr_t length, + uintptr_t page_size, + rtems_attribute attribute_set, + rtems_id *id + ); + +.. rubric:: PARAMETERS: + +``name`` + This parameter is the object name of the region. + +``starting_address`` + This parameter is the starting address of the memory area managed by the + region. + +``length`` + This parameter is the length in bytes of the memory area managed by the + region. + +``page_size`` + This parameter is the alignment of the starting address and length of each + allocated segment of the region. + +``attribute_set`` + This parameter is the attribute set of the region. + +``id`` + This parameter is the pointer to an :ref:`InterfaceRtemsId` object. When + the directive call is successful, the identifier of the created region will + be stored in this object. + +.. rubric:: DESCRIPTION: + +This directive creates a region which resides on the local node. The region +has the user-defined object name specified in ``name``. The assigned object +identifier is returned in ``id``. This identifier is used to access the region +with other region related directives. + +The region manages the **contiguous memory area** which starts at +``starting_address`` and is ``length`` bytes long. The memory area shall be +large enough to contain some internal region administration data. + +The **starting address** and **length of segments** allocated from the region +will be an integral multiple of ``page_size``. The specified page size will be +aligned to an implementation-dependent minimum alignment if necessary. + +The **attribute set** specified in ``attribute_set`` is built through a +*bitwise or* of the attribute constants described below. Not all combinations +of attributes are allowed. Some attributes are mutually exclusive. If +mutually exclusive attributes are combined, the behaviour is undefined. +Attributes not mentioned below are not evaluated by this directive and have no +effect. Default attributes can be selected by using the +:c:macro:`RTEMS_DEFAULT_ATTRIBUTES` constant. + +The **task wait queue discipline** is selected by the mutually exclusive +:c:macro:`RTEMS_FIFO` and :c:macro:`RTEMS_PRIORITY` attributes. The discipline +defines the order in which tasks wait for allocatable segments on a currently +empty region. + +* The **FIFO discipline** is the default and can be emphasized through use of + the :c:macro:`RTEMS_FIFO` attribute. + +* The **priority discipline** is selected by the :c:macro:`RTEMS_PRIORITY` + attribute. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_NAME` + The ``name`` parameter was invalid. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``id`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``starting_address`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_TOO_MANY` + There was no inactive object available to create a region. The number of + regions available to the application is configured through the + :ref:`CONFIGURE_MAXIMUM_REGIONS` application configuration option. + +:c:macro:`RTEMS_INVALID_SIZE` + The ``page_size`` parameter was invalid. + +:c:macro:`RTEMS_INVALID_SIZE` + The memory area specified in ``starting_address`` and ``length`` was too + small. + +.. rubric:: NOTES: + +For control and maintenance of the region, RTEMS allocates a :term:`RNCB` from +the local RNCB free pool and initializes it. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +* The number of regions available to the application is configured through the + :ref:`CONFIGURE_MAXIMUM_REGIONS` application configuration option. + +* Where the object class corresponding to the directive is configured to use + unlimited objects, the directive may allocate memory from the RTEMS + Workspace. + +.. Generated from spec:/rtems/region/if/ident + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_ident() + +.. _InterfaceRtemsRegionIdent: + +rtems_region_ident() +-------------------- + +Identifies a region by the object name. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_ident( rtems_name name, rtems_id *id ); + +.. rubric:: PARAMETERS: + +``name`` + This parameter is the object name to look up. + +``id`` + This parameter is the pointer to an :ref:`InterfaceRtemsId` object. When + the directive call is successful, the object identifier of an object with + the specified name will be stored in this object. + +.. rubric:: DESCRIPTION: + +This directive obtains a region identifier associated with the region name +specified in ``name``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``id`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_NAME` + The ``name`` parameter was 0. + +:c:macro:`RTEMS_INVALID_NAME` + There was no object with the specified name on the local node. + +.. rubric:: NOTES: + +If the region name is not unique, then the region identifier will match the +first region with that name in the search order. However, this region +identifier is not guaranteed to correspond to the desired region. + +The objects are searched from lowest to the highest index. Only the local node +is searched. + +The region identifier is used with other region related directives to access +the region. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within any runtime context. + +* The directive will not cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/delete + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_delete() +.. index:: delete a region + +.. _InterfaceRtemsRegionDelete: + +rtems_region_delete() +--------------------- + +Deletes the region. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_delete( rtems_id id ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +.. rubric:: DESCRIPTION: + +This directive deletes the region specified by ``id``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_RESOURCE_IN_USE` + There were segments of the region still in use. + +.. rubric:: NOTES: + +The region cannot be deleted if any of its segments are still allocated. + +The :term:`RNCB` for the deleted region is reclaimed by RTEMS. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +* The calling task does not have to be the task that created the object. Any + local task that knows the object identifier can delete the object. + +* Where the object class corresponding to the directive is configured to use + unlimited objects, the directive may free memory to the RTEMS Workspace. + +.. Generated from spec:/rtems/region/if/extend + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_extend() +.. index:: add memory to a region +.. index:: region, add memory + +.. _InterfaceRtemsRegionExtend: + +rtems_region_extend() +--------------------- + +Extends the region. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_extend( + rtems_id id, + void *starting_address, + uintptr_t length + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``starting_address`` + This parameter is the starting address of the memory area to extend the + region. + +``length`` + This parameter is the length in bytes of the memory area to extend the + region. + +.. rubric:: DESCRIPTION: + +This directive adds the memory area which starts at ``starting_address`` for +``length`` bytes to the region specified by ``id``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``starting_address`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The memory area specified by ``starting_address`` and ``length`` was + insufficient to extend the heap. + +.. rubric:: NOTES: + +There are no alignment requirements for the memory area. The memory area must +be big enough to contain some maintenance blocks. It must not overlap parts of +the current heap memory areas. Disconnected memory areas added to the heap +will lead to used blocks which cover the gaps. Extending with an inappropriate +memory area will corrupt the heap resulting in undefined behaviour. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/get-segment + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_get_segment() +.. index:: get segment from region + +.. _InterfaceRtemsRegionGetSegment: + +rtems_region_get_segment() +-------------------------- + +Gets a segment from the region. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_get_segment( + rtems_id id, + uintptr_t size, + rtems_option option_set, + rtems_interval timeout, + void **segment + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``size`` + This parameter is the size in bytes of the segment to allocate. + +``option_set`` + This parameter is the option set. + +``timeout`` + This parameter is the timeout in :term:`clock ticks <clock tick>` if the + :c:macro:`RTEMS_WAIT` option is set. Use :c:macro:`RTEMS_NO_TIMEOUT` to + wait potentially forever. + +``segment`` + This parameter is the pointer to a ``void`` pointer object. When the + directive call is successful, the begin address of the allocated segment + will be stored in this object. + +.. rubric:: DESCRIPTION: + +This directive gets a segment from the region specified by ``id``. + +The **option set** specified in ``option_set`` is built through a *bitwise or* +of the option constants described below. Not all combinations of options are +allowed. Some options are mutually exclusive. If mutually exclusive options +are combined, the behaviour is undefined. Options not mentioned below are not +evaluated by this directive and have no effect. Default options can be selected +by using the :c:macro:`RTEMS_DEFAULT_OPTIONS` constant. + +The calling task can **wait** or **try to get** a segment from the region +according to the mutually exclusive :c:macro:`RTEMS_WAIT` and +:c:macro:`RTEMS_NO_WAIT` options. + +* **Waiting to get** a segment from the region is the default and can be + emphasized through the use of the :c:macro:`RTEMS_WAIT` option. The + ``timeout`` parameter defines how long the calling task is willing to wait. + Use :c:macro:`RTEMS_NO_TIMEOUT` to wait potentially forever, otherwise set a + timeout interval in clock ticks. + +* **Trying to get** a segment from the region is selected by the + :c:macro:`RTEMS_NO_WAIT` option. If this option is defined, then the + ``timeout`` parameter is ignored. When a segment from the region cannot be + immediately allocated, then the :c:macro:`RTEMS_UNSATISFIED` status is + returned. + +With either :c:macro:`RTEMS_WAIT` or :c:macro:`RTEMS_NO_WAIT` if there is a +segment of the requested size is available, then it is returned in ``segment`` +and this directive returns immediately with the :c:macro:`RTEMS_SUCCESSFUL` +status code. + +If the calling task chooses to return immediately and the region has no segment +of the requested size available, then the directive returns immediately with +the :c:macro:`RTEMS_UNSATISFIED` status code. If the calling task chooses to +wait for a segment, then the calling task is placed on the region wait queue +and blocked. If the region was created with the :c:macro:`RTEMS_PRIORITY` +option specified, then the calling task is inserted into the wait queue +according to its priority. But, if the region was created with the +:c:macro:`RTEMS_FIFO` option specified, then the calling task is placed at the +rear of the wait queue. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``segment`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_SIZE` + The ``size`` parameter was zero. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_INVALID_SIZE` + The ``size`` parameter exceeded the maximum segment size which is possible + for the region. + +:c:macro:`RTEMS_UNSATISFIED` + The region had no segment of the requested size immediately available. + +:c:macro:`RTEMS_TIMEOUT` + The timeout happened while the calling task was waiting to get a segment + from the region. + +.. rubric:: NOTES: + +The actual length of the allocated segment may be larger than the requested +size because a segment size is always a multiple of the region's page size. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +* When the request cannot be immediately satisfied and the + :c:macro:`RTEMS_WAIT` option is set, the calling task blocks at some point + during the directive call. + +* The timeout functionality of the directive requires a :term:`clock tick`. + +.. Generated from spec:/rtems/region/if/return-segment + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_return_segment() +.. index:: return segment to region + +.. _InterfaceRtemsRegionReturnSegment: + +rtems_region_return_segment() +----------------------------- + +Returns the segment to the region. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_return_segment( rtems_id id, void *segment ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``segment`` + This parameter is the begin address of the segment to return. + +.. rubric:: DESCRIPTION: + +This directive returns the segment specified by ``segment`` to the region +specified by ``id``. The returned segment is merged with its neighbors to form +the largest possible segment. The first task on the wait queue is examined to +determine if its segment request can now be satisfied. If so, it is given a +segment and unblocked. This process is repeated until the first task's segment +request cannot be satisfied. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The segment was not within the region. + +.. rubric:: NOTES: + +This directive will cause the calling task to be preempted if one or more local +tasks are waiting for a segment and the following conditions exist: + +* A waiting task has a higher priority than the calling task. + +* The size of the segment required by the waiting task is less than or equal to + the size of the segment returned. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may unblock a task. This may cause the calling task to be + preempted. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/resize-segment + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_resize_segment() +.. index:: resize segment + +.. _InterfaceRtemsRegionResizeSegment: + +rtems_region_resize_segment() +----------------------------- + +Changes the size of the segment. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_resize_segment( + rtems_id id, + void *segment, + uintptr_t size, + uintptr_t *old_size + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``segment`` + This parameter is the begin address of the segment to resize. + +``size`` + This parameter is the requested new size of the segment. + +``old_size`` + This parameter is the pointer to an `uintptr_t + <https://en.cppreference.com/w/c/types/integer>`_ object. When the + directive call is successful, the old size of the segment will be stored in + this object. + +.. rubric:: DESCRIPTION: + +This directive is used to increase or decrease the size of the ``segment`` of +the region specified by ``id``. When increasing the size of a segment, it is +possible that there is no memory available contiguous to the segment. In this +case, the request is unsatisfied. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``old_size`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The segment was not within the region. + +:c:macro:`RTEMS_UNSATISFIED` + The region was unable to resize the segment. + +.. rubric:: NOTES: + +If an attempt to increase the size of a segment fails, then the application may +want to allocate a new segment of the desired size, copy the contents of the +original segment to the new, larger segment and then return the original +segment. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/get-information + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_get_information() +.. index:: obtain region information + +.. _InterfaceRtemsRegionGetInformation: + +rtems_region_get_information() +------------------------------ + +Gets the region information. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_get_information( + rtems_id id, + Heap_Information_block *the_info + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``the_info`` + This parameter is the pointer to a :c:type:`Heap_Information_block` object. + When the directive call is successful, the information of the region will + be stored in this object. + +.. rubric:: DESCRIPTION: + +This directive is used to obtain information about the used and free memory in +the region specified by ``id``. This is a snapshot at the time of the call. The +information will be returned in the structure pointed to by ``the_info``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``the_info`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +.. rubric:: NOTES: + +This is primarily intended as a mechanism to obtain a diagnostic information. +This method forms am O(n) scan of the free and an O(n) scan of the used blocks +in the region to calculate the information provided. Given that the execution +time is driven by the number of used and free blocks, it can take a +non-deterministic time to execute. + +To get only the free information of the region use +:ref:`InterfaceRtemsRegionGetFreeInformation`. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/get-free-information + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_get_free_information() +.. index:: obtain region information on free blocks + +.. _InterfaceRtemsRegionGetFreeInformation: + +rtems_region_get_free_information() +----------------------------------- + +Gets the region free information. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_get_free_information( + rtems_id id, + Heap_Information_block *the_info + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``the_info`` + This parameter is the pointer to a :c:type:`Heap_Information_block` object. + When the directive call is successful, the free information of the region + will be stored in this object. + +.. rubric:: DESCRIPTION: + +This directive is used to obtain information about the free memory in the +region specified by ``id``. This is a snapshot at the time of the call. The +information will be returned in the structure pointed to by ``the_info``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``the_info`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +.. rubric:: NOTES: + +This directive uses the same structure to return information as the +:ref:`InterfaceRtemsRegionGetInformation` directive but does not fill in the +used information. + +This is primarily intended as a mechanism to obtain a diagnostic information. +This method forms am O(n) scan of the free in the region to calculate the +information provided. Given that the execution time is driven by the number of +used and free blocks, it can take a non-deterministic time to execute. +Typically, there are many used blocks and a much smaller number of used blocks +making a call to this directive less expensive than a call to +:ref:`InterfaceRtemsRegionGetInformation`. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. + +.. Generated from spec:/rtems/region/if/get-segment-size + +.. raw:: latex + + \clearpage + +.. index:: rtems_region_get_segment_size() +.. index:: get size of segment + +.. _InterfaceRtemsRegionGetSegmentSize: + +rtems_region_get_segment_size() +------------------------------- + +Gets the size of the region segment. + +.. rubric:: CALLING SEQUENCE: + +.. code-block:: c + + rtems_status_code rtems_region_get_segment_size( + rtems_id id, + void *segment, + uintptr_t *size + ); + +.. rubric:: PARAMETERS: + +``id`` + This parameter is the region identifier. + +``segment`` + This parameter is the begin address of the segment. + +``size`` + This parameter is the pointer to a `uintptr_t + <https://en.cppreference.com/w/c/types/integer>`_ object. When the + directive call is successful, the size of the segment in bytes will be + stored in this object. + +.. rubric:: DESCRIPTION: + +This directive obtains the size in bytes of the segment specified by +``segment`` of the region specified by ``id`` in ``size``. + +.. rubric:: RETURN VALUES: + +:c:macro:`RTEMS_SUCCESSFUL` + The requested operation was successful. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``segment`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The ``size`` parameter was `NULL + <https://en.cppreference.com/w/c/types/NULL>`_. + +:c:macro:`RTEMS_INVALID_ID` + There was no region associated with the identifier specified by ``id``. + +:c:macro:`RTEMS_INVALID_ADDRESS` + The segment was not within the region. + +.. rubric:: NOTES: + +The actual length of the allocated segment may be larger than the requested +size because a segment size is always a multiple of the region's page size. + +.. rubric:: CONSTRAINTS: + +The following constraints apply to this directive: + +* The directive may be called from within device driver initialization context. + +* The directive may be called from within task context. + +* The directive may obtain and release the object allocator mutex. This may + cause the calling task to be preempted. |