source: rtems/doc/started/intro.t @ 874f9ed2

4.104.114.84.95
Last change on this file since 874f9ed2 was adee5979, checked in by Joel Sherrill <joel.sherrill@…>, on 05/04/00 at 19:45:17

Numerous changes based on comments from Stephan Wilms <Stephan.Wilms@…>
including a new section in the Getting Started called "Where to
Go From Here", lots of index entries added, and more configuration
table information.

  • Property mode set to 100644
File size: 8.0 KB
Line 
1@c
2@c  COPYRIGHT (c) 1988-1999.
3@c  On-Line Applications Research Corporation (OAR).
4@c  All rights reserved.
5@c
6@c  $Id$
7@c
8
9@chapter Introduction
10
11The purpose of this document is to guide you through the process of
12installing a GNU cross development environment to use with RTEMS.
13
14If you are already familiar with the concepts behind a cross compiler and
15have a background in Unix, these instructions should provide the bare
16essentials for performing a setup of the following items:
17
18@itemize @bullet
19@item GNU C/C++ Cross Compilation Tools for RTEMS on your host system
20@item RTEMS OS for the target host
21@item GDB Debugger
22@end itemize
23
24The remainder of this chapter provides background information on real-time
25embedded systems and cross development and an overview of other
26resources of interest on the Internet.  If you are not familiar with
27real-time embedded systems or the other areas, please read those sections. 
28These sections will help familiarize you with the
29types of systems RTEMS is designed to be used in and the cross development
30process used when developing RTEMS applications.
31
32@section Real-Time Embedded Systems
33
34Real-time embedded systems are found in practically every facet of our
35everyday lives.  Today's systems range from the common telephone, automobile
36control systems, and kitchen appliances to complex air traffic control
37systems, military weapon systems, an d production line control including
38robotics and automation. However, in the current climate of rapidly changing
39technology, it is difficult to reach a consensus on the definition of a
40real-time embedded system. Hardware costs are continuing to rapidly decline
41while at the same time the hardware is increasing in power and functionality.
42As a result, embedded systems that were not considered viable two years ago
43are suddenly a cost effective solution. In this domain, it is not uncommon
44for a single hardware configuration to employ a variety of architectures and
45technologies. Therefore, we shall define an embedded system as any computer
46system that is built into a larger system consisting of multiple technologies
47such as digital and analog electronics,  mechanical devices, and sensors.
48
49Even as hardware platforms become more powerful, most embedded systems are
50critically dependent on the real-time software embedded in the systems
51themselves.  Regardless of how efficiently the hardware operates, the
52performance of the embedded real-time software determines the success of the
53system.  As the complexity of the embedded hardware platform grows, so does
54the size and complexity of the embedded software. Software systems must
55routinely perform activities which were only dreamed of a short time ago.
56These large, complex, real-time embedded applications now commonly contain
57one million lines of code or more.
58
59Real-time embedded systems have a complex set of characteristics that
60distinguish them from other software applications.  Real-time embedded
61systems are driven by and must respond to real world events while adhering to
62rigorous requirements imposed by the environment with which they interact.
63The correctness of the system depends not only on the results of
64computations, but also on the time at which the results are produced.  The
65most important and complex characteristic of real-time application systems is
66that they must receive and respond to a set of external stimuli within rigid
67and critical time constraints.
68
69A single real-time application can be composed of both soft and hard
70real-time components. A typical example of a hard real-time system is a
71nuclear reactor control system that must not only detect failures, but must
72also respond quickly enough to prevent a meltdown. This application also has
73soft real-time requirements because it may involve a man-machine interface.
74Providing an interactive input to the control system is not as critical as
75setting off an alarm to indicate a failure condition. However, th e
76interactive system component must respond within an acceptable time limit to
77allow the operator to interact efficiently with the control system.
78
79@section Cross Development
80
81Today almost all real-time embedded software systems are developed in a
82@b{cross development} environment using cross development tools. In the cross
83development environment, software development activities are typically
84performed on one computer system, the @b{host} system, while the result of the
85development effort (produced by the cross tools) is a software system that
86executes on the @b{target} platform. The requirements for the target platform are
87usually incompatible and quite often in direct conflict with the requirements
88for the host.  Moreover, the target hardware is often custom designed for a
89particular project.  This means that the cross development toolset must allow
90the developer to customize the tools to address target specific run-time
91issues.  The toolset must have provisions for board dependent initialization
92code, device drivers, and error handling code.
93
94The host computer is optimized to support the code development cycle with
95support for code editors, compilers, and linkers requiring large disk drives,
96user development windows, and multiple developer connections.  Thus the host
97computer is typically a traditional UNIX workstation such as are available
98from SUN or Silicon Graphics, or a PC running either a version of MS-Windows
99or UNIX.  The host system may also be required to execute office productivity
100applications to allow the software developer to write  documentation, make
101presentations, or track the project's progress using a project management
102tool.  This necessitates that the host computer be general purpose with
103resources such as a thirty-two or sixty-four bit processor, large amounts of
104RAM, a  monitor, mouse, keyboard, hard and floppy disk drives, CD-ROM drive,
105and a graphics card.  It is likely that the system will be multimedia capable
106and have some networking capability.
107
108Conversely, the target platform generally has limited traditional computer
109resources.  The hardware is designed for the particular functionality and
110requirements of the embedded system and optimized to perform those tasks
111effectively.  Instead of hard  driverss and keyboards, it is composed of
112sensors, relays, and stepper motors. The per-unit cost of the target platform
113is typically a critical concern.  No hardware component is included without
114being cost justified.  As a result, the processor of the target system is
115often from a different processor family than that of the host system and
116usually has lower performance.  In addition to the processor families
117targeted only for use in embedded systems, there are versions of nearly every
118general-purpose process or specifically tailored for real-time embedded
119systems.  For example, many of the processors targeting the embedded market
120do not include hardware floating point units, but do include peripherals such
121as timers, serial controllers, or network interfaces.
122
123@section Resources on the Internet
124
125This section describes various resources on the Internet which are of
126use to RTEMS users.
127
128@subsection RTEMS Mailing List
129
130rtems-users@@OARcorp.com
131
132This mailing list is dedicated to the discussion of issues related
133to RTEMS, including GNAT/RTEMS.  If you have questions about RTEMS,
134wish to make suggestions, or just want to pick up hints, this is a
135good list to subscribe to.  Subscribe by sending an empty mail
136message to rtems-users-subscribe@@OARcorp.com.  Messages sent
137to rtems-users@@OARcorp.com are posted to the list.
138
139@subsection CrossGCC Mailing List
140
141crossgcc@@cygnus.com
142
143This mailing list is dedicated to the use of the GNU tools in
144cross development environments.  Most of the discussions
145focus on embedded issues.  Subscribe by sending a message with
146the one line "subscribe" to crossgcc-request@@cygnus.com.
147
148The crossgcc FAQ as well as a number of patches and utiliities
149of interest to cross development system users are available
150at ftp://ftp.cygnus.com/pub/embedded/crossgcc.
151
152@subsection GCC Mailing Lists
153
154See http://gcc.gnu.org for details.
155
156The GCC Project maintains multiple mailing lists.  They
157are described at the above web site along with subscription
158information.
159
Note: See TracBrowser for help on using the repository browser.