24.21. Multiprocessing Configuration — RTEMS Classic API Guide 5.4-rc2 (21st August 2026) documentation

# 24.21. Multiprocessing Configuration

This section describes multiprocessing related configuration options. The options are only used if RTEMS was built with the `--enable-multiprocessing` build configuration option. Additionally, this class of configuration options are only applicable if the configuration option CONFIGURE_MP_APPLICATION is defined. The multiprocessing (MPCI) support must not be confused with the SMP support.

## 24.21.1. CONFIGURE_MP_APPLICATION

CONSTANT:

  `CONFIGURE_MP_APPLICATION`

OPTION TYPE:

  This configuration option is a boolean feature define.

DEFAULT CONFIGURATION:

  If this configuration option is undefined, then the multiprocessing services are not initialized.

DESCRIPTION:

  This configuration option is defined to indicate that the application intends to be part of a multiprocessing configuration. Additional configuration options are assumed to be provided.

NOTES:

  This configuration option shall be undefined if the multiprocessing support is not enabled (e.g. RTEMS was built without the `--enable-multiprocessing` build configuration option). Otherwise a compile time error in the configuration file will occur.

## 24.21.2. CONFIGURE_EXTRA_MPCI_RECEIVE_SERVER_STACK

CONSTANT:

  `CONFIGURE_EXTRA_MPCI_RECEIVE_SERVER_STACK`

OPTION TYPE:

  This configuration option is an integer define.

DEFAULT VALUE:

  The default value is 0.

VALUE CONSTRAINTS:

  The value of this configuration option shall satisfy all of the following constraints:

  - It shall be greater than or equal to 0.

  - It shall be less than or equal to `UINT32_MAX`.

  - It shall be small enough so that the MPCI receive server stack area calculation carried out by `<rtems/confdefs.h>` does not overflow an integer of type `size_t`.

DESCRIPTION:

  The value of this configuration option defines the number of bytes the applications wishes to add to the MPCI task stack on top of CONFIGURE_MINIMUM_TASK_STACK_SIZE.

NOTES:

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.

## 24.21.3. CONFIGURE_MP_MAXIMUM_GLOBAL_OBJECTS

CONSTANT:

  `CONFIGURE_MP_MAXIMUM_GLOBAL_OBJECTS`

OPTION TYPE:

  This configuration option is an integer define.

DEFAULT VALUE:

  The default value is 32.

VALUE CONSTRAINTS:

  The value of this configuration option shall be greater than or equal to 0 and less than or equal to `UINT32_MAX`.

DESCRIPTION:

  The value of this configuration option defines the maximum number of concurrently active global objects in a multiprocessor system.

NOTES:

  This value corresponds to the total number of objects which can be created with the `RTEMS_GLOBAL` attribute.

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.

## 24.21.4. CONFIGURE_MP_MAXIMUM_NODES

CONSTANT:

  `CONFIGURE_MP_MAXIMUM_NODES`

OPTION TYPE:

  This configuration option is an integer define.

DEFAULT VALUE:

  The default value is 2.

VALUE CONSTRAINTS:

  The value of this configuration option shall be greater than or equal to 0 and less than or equal to `UINT32_MAX`.

DESCRIPTION:

  The value of this configuration option defines the maximum number of nodes in a multiprocessor system.

NOTES:

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.

## 24.21.5. CONFIGURE_MP_MAXIMUM_PROXIES

CONSTANT:

  `CONFIGURE_MP_MAXIMUM_PROXIES`

OPTION TYPE:

  This configuration option is an integer define.

DEFAULT VALUE:

  The default value is 32.

VALUE CONSTRAINTS:

  The value of this configuration option shall be greater than or equal to 0 and less than or equal to `UINT32_MAX`.

DESCRIPTION:

  The value of this configuration option defines the maximum number of concurrently active thread/task proxies on this node in a multiprocessor system.

NOTES:

  Since a proxy is used to represent a remote task/thread which is blocking on this node. This configuration parameter reflects the maximum number of remote tasks/threads which can be blocked on objects on this node, see Proxies.

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.

## 24.21.6. CONFIGURE_MP_MPCI_TABLE_POINTER

CONSTANT:

  `CONFIGURE_MP_MPCI_TABLE_POINTER`

OPTION TYPE:

  This configuration option is an initializer define.

DEFAULT VALUE:

  The default value is `&MPCI_table`.

VALUE CONSTRAINTS:

  The value of this configuration option shall be a pointer to `rtems_mpci_table`.

DESCRIPTION:

  The value of this configuration option initializes the MPCI Configuration Table.

NOTES:

  RTEMS provides a Shared Memory MPCI Device Driver which can be used on any Multiprocessor System assuming the BSP provides the proper set of supporting methods.

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.

## 24.21.7. CONFIGURE_MP_NODE_NUMBER

CONSTANT:

  `CONFIGURE_MP_NODE_NUMBER`

OPTION TYPE:

  This configuration option is an integer define.

DEFAULT VALUE:

  The default value is `NODE_NUMBER`.

VALUE CONSTRAINTS:

  The value of this configuration option shall be greater than or equal to 0 and less than or equal to `UINT32_MAX`.

DESCRIPTION:

  The value of this configuration option defines the node number of this node in a multiprocessor system.

NOTES:

  In the RTEMS Multiprocessing Test Suite, the node number is derived from the Makefile variable `NODE_NUMBER`. The same code is compiled with the `NODE_NUMBER` set to different values. The test programs behave differently based upon their node number.

  This configuration option is only evaluated if CONFIGURE_MP_APPLICATION is defined.