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|
SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
brief: |
The application configuration information group provides an API to get the
configuration of an application.
copyrights:
- Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
- Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
description: |
RTEMS must be configured for an application. This configuration encompasses a
variety of information including the length of each clock tick, the maximum
number of each information RTEMS object that can be created, the application
initialization tasks, the task scheduling algorithm to be used, and the device
drivers in the application.
Although this information is contained in data structures that are used by
RTEMS at system initialization time, the data structures themselves must not be
generated by hand. RTEMS provides a set of macros system which provides a
simple standard mechanism to automate the generation of these structures.
The RTEMS header file ``<rtems/confdefs.h>`` is at the core of the automatic
generation of system configuration. It is based on the idea of setting macros
which define configuration parameters of interest to the application and
defaulting or calculating all others. This variety of macros can automatically
produce all of the configuration data required for an RTEMS application. The
term ``confdefs`` is shorthand for a *Configuration Defaults*.
As a general rule, application developers only specify values for the
configuration parameters of interest to them. They define what resources or
features they require. In most cases, when a parameter is not specified, it
defaults to zero (0) instances, a standards compliant value, or disabled as
appropriate. For example, by default there will be 256 task priority levels but
this can be lowered by the application. This number of priority levels is
required to be compliant with the RTEID/ORKID standards upon which the Classic
API is based. There are similar cases where the default is selected to be
compliant with the POSIX standard.
For each configuration parameter in the configuration tables, the macro
corresponding to that field is discussed. The RTEMS Maintainers expect that all
systems can be easily configured using the ``<rtems/confdefs.h>`` mechanism and
that using this mechanism will avoid internal RTEMS configuration changes
impacting applications.
Some application configuration settings and other system parameters can be
queried by the application.
enabled-by: true
identifier: RTEMSAPIConfig
index-entries:
- confdefs.h
- <rtems/confdefs.h>
interface-type: group
links:
- role: interface-placement
uid: header
- role: interface-ingroup
uid: /if/group
- role: placement-order
uid: get-build-label
- role: placement-order
uid: get-copyright-notice
- role: placement-order
uid: get-target-hash
- role: placement-order
uid: get-version-string
- role: placement-order
uid: get-do-zero-of-workspace
- role: placement-order
uid: get-idle-task-stack-size
- role: placement-order
uid: get-idle-task
- role: placement-order
uid: get-interrupt-stack-size
- role: placement-order
uid: get-maximum-barriers
- role: placement-order
uid: get-maximum-extensions
- role: placement-order
uid: get-maximum-message-queues
- role: placement-order
uid: get-maximum-partitions
- role: placement-order
uid: get-maximum-periods
- role: placement-order
uid: get-maximum-ports
- role: placement-order
uid: get-maximum-processors
- role: placement-order
uid: get-maximum-regions
- role: placement-order
uid: get-maximum-semaphores
- role: placement-order
uid: get-maximum-tasks
- role: placement-order
uid: get-maximum-timers
- role: placement-order
uid: get-microseconds-per-tick
- role: placement-order
uid: get-milliseconds-per-tick
- role: placement-order
uid: get-nanoseconds-per-tick
- role: placement-order
uid: get-number-of-initial-extensions
- role: placement-order
uid: get-stack-allocate-for-idle-hook
- role: placement-order
uid: get-stack-allocate-hook
- role: placement-order
uid: get-stack-allocate-init-hook
- role: placement-order
uid: get-stack-allocator-avoids-work-space
- role: placement-order
uid: get-stack-free-hook
- role: placement-order
uid: get-stack-space-size
- role: placement-order
uid: get-ticks-per-timeslice
- role: placement-order
uid: get-unified-work-area
- role: placement-order
uid: get-user-extension-table
- role: placement-order
uid: get-user-multiprocessing-table
- role: placement-order
uid: get-work-space-size
- role: placement-order
uid: get-api-configuration
- role: placement-order
uid: resource-is-unlimited
- role: placement-order
uid: resource-maximum-per-allocation
- role: placement-order
uid: resource-unlimited
name: Application Configuration Information
text: |
The RTEMS API shall provide an interface to get the configuration of an
application.
type: interface
|
