SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
appl-config-option-type: feature-enable
copyrights:
- Copyright (C) 2010 Gedare Bloom
- Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
description: |
  In case this configuration option is defined, then the user shall provide a
  scheduler algorithm to the application.
enabled-by: true
index-entries: []
interface-type: appl-config-option
links:
- role: appl-config-group-member
  uid: group-schedgeneral
name: CONFIGURE_SCHEDULER_USER
notes: |
  This scheduler configuration option is an advanced configuration option.
  Think twice before you use it.

  RTEMS allows the application to provide its own task/thread scheduling
  algorithm. In order to do this, one shall define
  ``CONFIGURE_SCHEDULER_USER`` to indicate the application provides its own
  scheduling algorithm. If ``CONFIGURE_SCHEDULER_USER`` is defined then the
  following additional macros shall be defined:

  * ``CONFIGURE_SCHEDULER`` shall be defined to a static definition of
    the scheduler data structures of the user scheduler.

  * ``CONFIGURE_SCHEDULER_TABLE_ENTRIES`` shall be defined to a scheduler
    table entry initializer for the user scheduler.

  * ``CONFIGURE_SCHEDULER_USER_PER_THREAD`` shall be defined to the type of
    the per-thread information of the user scheduler.

  At this time, the mechanics and requirements for writing a new scheduler
  are evolving and not fully documented.  It is recommended that you look at
  the existing Deterministic Priority Scheduler in
  ``cpukit/score/src/schedulerpriority*.c`` for guidance.  For guidance on
  the configuration macros, please examine ``cpukit/sapi/include/confdefs.h``
  for how these are defined for the Deterministic Priority Scheduler.
text: ''
type: interface