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user: Rework overview
Move "Overview", "Real-time Applicaiton Systems" and "Real-time Executive" chapters as sections into new "Introduction" chapter. Add "Feature" section.
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Sebastian Huber
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@ -11,6 +11,12 @@ Glossary
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architectures follow the GCC architecture model as RTEMS needs an GCC
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architecture compiler for each support RTEMS architecture.
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APA
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Arbitrary Processor Affinity
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API
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Application Programming Interface
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Binutils
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GNU Binary Utilities such as the assembler ``as``, linker ``ld`` and a
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range of other tools used in the development of software.
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@ -23,6 +29,12 @@ Glossary
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Buildbot
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A continuous inteagration build server.
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C11
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ISO/IEC 9899:2011
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C++11
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ISO/IEC 14882:2011
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Crosscompiler
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A compiler built to run on a Host that generate code for another
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@ -31,12 +43,33 @@ Glossary
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DLL
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Dynamically Linker Library used on Windows.
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EDF
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Earliest Deadline First
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EMB²
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`Embedded Multicore Building Blocks <https://embb.io>`_
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FAT
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File Allocation Table
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Futex
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Fast User-Space Locking
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IMFS
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In-Memory File System
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JFFS2
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Journalling Flash File System version 2
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GCC
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GNU Compiler Tool chain. It is the GNU C/C++ compiler, binutils and GDB.
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GNU Compiler Collection
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GDB
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GNU Debugger
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GNU
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GNU's Not Unix
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Host
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The computer and operating system that hosts the RTEMS development tools
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such as the compiler, linker and debugger.
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@ -49,6 +82,9 @@ Glossary
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MinGW64
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Minimal GNU system for 64bit Windows. MinGW64 is not the MinGW project.
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MrsP
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Multiprocessor Resource-Sharing Protocol
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MSYS2
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Minimal System 2 is a fork of the MinGW project's MSYS tool and the MinGW
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MSYS tool is a fork of Cygwin project. The Cygwin project provides a POSIX
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@ -57,6 +93,15 @@ Glossary
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has a simplified path structure to make it easier to building native Windows
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programs.
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NFSv2
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Network File System version 2
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OMIP
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:math:`O(m)` Independence-Preserving Protocol
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OpenMP
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Open Multi-Processing
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POSIX
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Portable Operating System Interface is a standard that lets software be
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portable between compliant operating systems.
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@ -65,6 +110,9 @@ Glossary
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A path used when building a package so all parts of the package reside
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under that path.
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RFS
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RTEMS File System
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RSB
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RTEMS Source Builder is part of the RTEMS Tools Project. It builds packages
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such as the tools for the RTEMS operating system.
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@ -75,6 +123,9 @@ Glossary
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variety of open standard application programming interfaces (API) and
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interface standards such as POSIX and BSD sockets.
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SMP
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Symmetric Multiprocessing
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Target
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A target is the hardware or simulator a BSP built executable runs on.
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@ -84,5 +135,11 @@ Glossary
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Testsuite
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RTEMS test suite located in the ``testsuites/`` directory.
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TLS
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Thread-Local Storage
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Waf
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Waf build system. For more information see http://www.waf.io/
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YAFFS2
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`Yet Another Flash File System version 2 <https://git.rtems.org/sebh/rtems-yaffs2.git>`_
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@ -1,60 +1,189 @@
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.. comment SPDX-License-Identifier: CC-BY-SA-4.0
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Introduction
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============
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Overview
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========
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--------
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Welcome to the :ref:term:`RTEMS` User Manual.
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You are someone looking for a real-time operating system. This document
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This document covers the topics a user of RTEMS needs to be able to install,
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configure, build and create applications for the RTEMS operating system.
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- presents the basic features of RTEMS, so that you can decide if it is worth to
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look at,
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RTEMS, Real-Time Executive for Multiprocessor Systems, is a real-time executive
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(kernel) which provides a high performance environment for embedded
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applications with the following features:
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- gives you a :ref:`quick start <QuickStart>` to install all the tools
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necessary to work with RTEMS, and
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.. sidebar:: Developers
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- helps you to build an example application on top of RTEMS.
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Developers should look at the :r:url:`devel` for technical information. The
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design and development of RTEMS is located there.
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Features
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--------
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- standards based user interfaces
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The Real-Time Executive for Multiprocessor Systems (:ref:term:`RTEMS`) is a
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multi-threaded, single address-space, real-time operating system with no
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kernel-space/user-space separation. It is capable to operate in an
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:ref:term:`SMP` configuration providing a state of the art feature set.
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- multitasking capabilities
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RTEMS is licensed under a
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`modified GPL 2.0 or later license with an exception for static linking <https://git.rtems.org/rtems/tree/LICENSE>`_
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[#]_. It exposes no license requirements on application code. The third-party
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software used and distributed by RTEMS which may be linked to the application
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is licensed under permissive open source licenses. Everything necessary to
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build RTEMS applications is available as open source software. This makes you
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completely vendor independent.
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- homogeneous and heterogeneous multiprocessor systems
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RTEMS provides the following basic feature set:
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- event-driven, priority-based, preemptive scheduling
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- :ref:term:`APIs <API>`
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- optional rate monotonic scheduling
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- :ref:term:`POSIX` with
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`pthreads <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/pthread.h.html>`_
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(enables a broad range of standard software to run on RTEMS)
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- intertask communication and synchronization
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- `Classic <https://docs.rtems.org/branches/master/c-user.pdf>`_
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- priority inheritance
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- :ref:term:`C11` (including
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`thread <https://en.cppreference.com/w/c/thread>`_ support)
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- responsive interrupt management
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- :ref:term:`C++11` (including
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`thread <https://en.cppreference.com/w/cpp/thread>`_ support)
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- dynamic memory allocation
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- Newlib and :ref:term:`GCC` internal
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- high level of user configurability
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- Programming languages
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- open source with a friendly user license
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- C/C++/OpenMP (RTEMS Source Builder, RSB)
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RTEMS provides features found in modern operating systems:
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- Ada (RSB, ``--with-ada``)
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- file systems
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- Erlang
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- networking
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- Fortran (RSB, ``--with-fortran``)
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- USB
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- Python and MicroPython
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- permanent media such as flash disks, cards and USB devices
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- Parallel languages
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- support for various languages
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- :ref:term:`EMB²`
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- parallel programming language support
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- Google Go [#]_
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- :ref:term:`OpenMP` 4.5
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- Thread synchronization and communication
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- Mutexes with and without locking protocols
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- Counting semaphores
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- Binary semaphores
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- Condition variables
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- Events
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- Message queues
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- Barriers
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- :ref:term:`Futex` (used by :ref:term:`OpenMP` barriers)
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- Epoch Based Reclamation (libbsd)
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- Locking protocols
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- Transitive Priority Inheritance
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- :ref:term:`OMIP` (SMP feature)
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- Priority Ceiling
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- :ref:term:`MrsP` (SMP feature)
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- Scalable timer and timeout support
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- Lock-free timestamps (FreeBSD timecounters)
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- Responsive interrupt management
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- C11/C++11 :ref:term:`TLS` [#]_
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- Link-time configurable schedulers
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- Fixed-priority
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- Job-level fixed-priority (:ref:term:`EDF`)
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- Constant Bandwidth Server (experimental)
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- Clustered scheduling (SMP feature)
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- Flexible link-time configuration
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- Job-level fixed-priority scheduler (:ref:term:`EDF`) with support for
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one-to-one and one-to-all thread to processor affinities (default SMP
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scheduler)
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- Fixed-priority scheduler
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- Proof-of-concept strong :ref:term:`APA` scheduler
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- Focus on link-time application-specific configuration
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- Linker-set based initialization (similar to global C++ constructors)
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- Operating system uses fine-grained locking (SMP feature)
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- Dynamic memory allocators
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- First-fit (default)
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- Universal Memory Allocator
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(`UMA <https://www.freebsd.org/cgi/man.cgi?query=uma&sektion=9>`_ ,
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libbsd)
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- File systems
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- :ref:term:`IMFS`
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- :ref:term:`FAT`
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- :ref:term:`RFS`
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- :ref:term:`NFSv2`
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- :ref:term:`JFFS2` (NOR flashes)
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- :ref:term:`YAFFS2` (NAND flashes, GPL or commercial license required)
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- Device drivers
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- Termios (serial interfaces)
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- I2C (Linux user-space API compatible)
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- SPI (Linux user-space API compatible)
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- Network stacks (legacy, libbsd, lwIP)
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- USB stack (libbsd)
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- SD/MMC card stack (libbsd)
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- Framebuffer (Linux user-space API compatible, Qt)
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- Application runs in kernel-space and can access hardware directly
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- libbsd
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- Port of FreeBSD user-space and kernel-space components to RTEMS
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- Easy access to FreeBSD software for RTEMS
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- Support to stay in synchronization with FreeBSD
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Real-time Application Systems
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=============================
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-----------------------------
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Real-time application systems are a special class of computer applications.
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They have a complex set of characteristics that distinguish them from other
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@ -89,7 +218,7 @@ competing processors are introduced. The ramifications of multiple processors
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complicate each and every characteristic of a real-time system.
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Real-time Executive
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===================
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-------------------
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Fortunately, real-time operating systems, or real-time executives, serve as a
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cornerstone on which to build the application system. A real-time multitasking
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@ -127,3 +256,17 @@ routines to manage memory, pass messages, or provide mutual exclusion. The
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developer is then able to concentrate solely on the application. By using
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standard software components, the time and cost required to develop
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sophisticated real-time applications are significantly reduced.
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.. [#] The goal is to use the
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`BSD 2-Clause license
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<https://git.rtems.org/rtems/tree/LICENSE.BSD-2-Clause>`_ for new code
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or code those copyright holder agreed to a license change, see `#3053
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<https://devel.rtems.org/ticket/3053>`_ for the details.
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.. [#] See `#2832 <https://devel.rtems.org/ticket/2832>`_.
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.. [#] Thread-local storage requires some support by the tool chain and the
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RTEMS architecture support, e.g. context-switch code. It is supported
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at least on ARM, PowerPC, RISC-V, SPARC and m68k. Check the
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`RTEMS CPU Architecture Supplement <https://docs.rtems.org/branches/master/cpu-supplement.pdf>`_
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if it is supported.
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@ -5,6 +5,8 @@
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.. index:: Quick Start
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.. _QuickStart:
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Quick Start
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***********
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