introduction.sgml

eCos操作系统源码

<para>The result is a royalty-free system with minimal obligations on
the part of application developers. This has resulted in the rapid
uptake of <productname>eCos</productname>. At the same time,
<productname>eCos</productname> is fully open source with all the
benefits that implies in terms of quality and innovation. We believe
that this is a winning combination.</para>

<sect1 id="ecos-licensing-qna">
<title>Questions and answers</title>

<para>The following queries provide some clarification as to the
implications of the <productname>eCos</productname> license. They do
not consititute part of the legal meaning of the license.</para>

<para><emphasis>Q.</emphasis> What is the effect of the
<productname>eCos</productname> license?</para>

<para><emphasis>A.</emphasis> In the simplest terms, when you
distribute anything containing <productname>eCos</productname> code,
you must make the source code to <productname>eCos</productname>
available under the terms of the GPL.</para>

<para><emphasis>Q.</emphasis> What if I make changes to
<productname>eCos</productname>, or write new code based on
<productname>eCos</productname> code?</para>

<para><emphasis>A.</emphasis> Then you must make those changes
available as well.</para>

<para><emphasis>Q.</emphasis> Do I have to distribute the source
code to my application? Isn't the GPL "viral"?</para>

<para><emphasis>A.</emphasis> You do not have to distribute any
code under the terms of the GPL other than
<productname>eCos</productname> code or code derived from
<productname>eCos</productname>. For example, if you write a HAL port
based on copying an existing <productname>eCos</productname> HAL in
any way, you must make the source code available with the
binary. However you would not need to make available any other code,
such as the code of a wholly separate application linked with
<productname>eCos</productname>.</para>

<para><emphasis>Q.</emphasis> I would rather stick with the
RHEPL code, but I updated my anonymous CVS checkout.</para>

<para><emphasis>A.</emphasis> You can check out the final
version of anonymous CVS before the license change using the CVS tag
<literal>last-rhepl</literal>. See <ulink
url="http://ecos.sourceware.org/anoncvs.html">the anonymous CVS
access page</ulink>
for details.</para>

</sect1>

<sect1 id="ecos-licensing-previous">
<title>Previous License</title>

<para>

Prior to May 2002, <productname>eCos</productname> was released under
the <ulink url="http://ecos.sourceware.org/old-license.html">Red
Hat eCos Public License (RHEPL)</ulink>. The RHEPL required any
modifications to <productname>eCos</productname> code to be made
available under preferential terms to Red Hat and was therefore
incompatible with code licensed under the GPL.  The use of
<productname>eCos</productname> source code which was licensed under
the RHEPL is not affected by the switch to the modified GPL for later
revisions.
</para>

</sect1>

</chapter>

<!-- ==================================================== -->

<chapter id="notation-and-conventions">
<title>Notation and Conventions</title>

<para>
Since there are many supported target architectures, notation
conventions are used in this manual to avoid repeating instructions
that are very similar.
</para>

<SECT1 ID="GDB-AND-GCC-COMMAND-NOTATION"><!-- <index></index> --><!-- <xref> -->
<TITLE>GDB and <!-- <index></index> -->GCC Command Notation</TITLE>

<para>
Cross-development commands like <COMMAND>gcc</COMMAND> and
<COMMAND>gdb</COMMAND> will be shown with a
<replaceable>TARGET-</replaceable> prefix. You need to replace
<replaceable>TARGET-</replaceable> with the correct prefix before
using the command. Just using <command>gcc</command> or
<command>gdb</command> will use the tools for the host, which is not
(usually) what you want.
</para>

<para>
For example use <command>arm-elf-gcc</command> and
<command>arm-elf-gdb</command> for ARM, Thumb, and StrongARM targets.
Use <command>xscale-elf-gcc</command> and
<command>xscale-elf-gdb</command> for Intel Xscale targets.
Use <command>i386-elf-gcc</command> and
<command>i386-elf-gdb</command> for IA32 targets. And so on, the exact
prefix to use is shown in the documentation for each target.
</para>

<PARA>Note that some versions of the GCC cross compiler generate
executable files with the <FILENAME>.exe</FILENAME> suffix on Windows,
but not on Linux. The suffix <FILENAME>.exe</FILENAME> will be omitted
from executable file names, so you will see <FILENAME>hello</FILENAME>
instead of <FILENAME>hello.exe</FILENAME>.</PARA>

</sect1>

<SECT1 ID="DIRECTORY-AND-FILE-SYSTEM-CONVENTIONS"><!-- <index></index> -->
<TITLE>Directory and File System Conventions</TITLE>

<PARA>The default directory for installing
<productname>eCos</productname> on Windows (usually
<FILENAME>C:/Program Files/eCos</FILENAME>) is different from that on
Linux (usually <FILENAME>/opt/ecos</FILENAME>).  Since many command
line examples in the tutorials use these paths, this default (base)
directory will be cited as <replaceable>BASE_DIR</replaceable>.</PARA>

<PARA>Windows and Linux have a similar file system syntax, but the
MS-DOS command interpreter on Windows uses the backslash character
(\) as a path separator, while Linux and POSIX shells (including
the Cygwin bash shell for windows) use the forward slash (/).</PARA>

<PARA>This document will use the POSIX shell convention of forward
slashes throughout.</PARA>

</SECT1>

<!-- ==================================================== -->

<SECT1 ID="VERSION-CONVENTIONS">
<TITLE>Version Conventions</TITLE>

<para>
This manual does not refer explicitly to any particular version of
<productname>eCos</productname>. However, version numbers form part of
many file path names. In all of these places the version number will
be shown like this: <replaceable>&Version;</replaceable>.
</para>

<para>
If you have used anonymous CVS to check
<productname>eCos</productname> out of the CVS repository, the version
number will always be <literal>current</literal>, since that is the
name of the directory in the repository. When a stable release is made
this directory name is changed, in the release, to the number of the
release, for example <literal>v2_0</literal> or
<literal>v2_1</literal>.
</para>

</SECT1>


</chapter>



<chapter id="documentation-roadmap">
<title>Documentation Roadmap</title>

<para>
The <productname>eCos</productname> documentation is divided into a
three main parts:
</para>

<VARIABLELIST>
<VARLISTENTRY>
<TERM><EMPHASIS>User Guide</EMPHASIS></TERM>
<LISTITEM>
<PARA>This document. It includes the following sections:</PARA>

  <VARIABLELIST>
  <VARLISTENTRY>
  <TERM>Installing <productname>eCos</productname></TERM>
  <LISTITEM>
  <para>
  This section describes how to install the
  <productname>eCos</productname> software, how to set up your
  hardware and how to test that it is all working.
  </para>
  </listitem>
  </varlistentry>

  <VARLISTENTRY>
  <TERM>Programming Under <productname>eCos</productname></TERM>
  <LISTITEM>
  <para>
  This section describes how to write programs that run under
  <productname>eCos</productname> by running through some examples.
  </para>
  </listitem>
  </varlistentry>

  <VARLISTENTRY>
  <TERM>The <productname>eCos</productname> <application>Configuration Tool</application></TERM>
  <LISTITEM>
  <para>
  This section describes the <productname>eCos</productname> graphical
  configuration tool and how to use it to change how
  <productname>eCos</productname> behaves.</para>
  </listitem>
  </varlistentry>

  <VARLISTENTRY>
  <TERM><productname>eCos</productname> Programming Concepts and Techniques</TERM>
  <LISTITEM>
  <PARA>An explanation of the <productname>eCos</productname> programming
	    cycle, and a description of some debugging facilities that
	    <productname>eCos</productname> offers.
  </PARA>
  </listitem>
  </varlistentry>

  <VARLISTENTRY>
  <TERM>Configuration and the Package
              Repository</TERM>
  <LISTITEM>
  <PARA>Information on how to configure <productname>eCos</productname>
              manually, including a reference on the
              <command>ecosconfig</command> command, memory layouts,
              and information on how to manage a package repository
              using the <productname>eCos</productname> Package Administration
              Tool.
            </PARA>
  </LISTITEM>
  </VARLISTENTRY>


  </variablelist>

</LISTITEM>
</VARLISTENTRY>

<VARLISTENTRY>
<TERM><EMPHASIS>Reference Guide</EMPHASIS></TERM>
<LISTITEM>

<PARA>The Reference Guide provides detailed documentation on various
aspects of <productname>eCos</productname>. This document is being
constantly updated, so the following list just mentions the more
important sections, take a look at the guide itself for the full
story.</PARA>

  <variablelist>

  <VARLISTENTRY>
  <TERM>The <productname>eCos</productname> Kernel</TERM>
  <LISTITEM>
  <PARA>In-depth description of <productname>eCos</productname>&quot;s
              native C kernel API Important considerations are given
              for programming the <productname>eCos</productname>
              kernel. The semantics for each kernel function are
              described, including how they are affected by
              configuration. </PARA>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>POSIX and &micro;ITRON APIs</TERM>
  <LISTITEM>
  <PARA>A description of the POSIX and &micro;ITRON APIs and how they
  are supported under <productname>eCos</productname>.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>The <productname>eCos</productname> Hardware Abstraction Layer (HAL)</TERM>
  <LISTITEM>
  <PARA>A description of the structure and functionality of the
  <productname>eCos</productname> HAL. This section also includes a
  porting guide to help moving <productname>eCos</productname> to
  different platforms.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>Device Drivers</TERM>
  <LISTITEM>
  <PARA>A description of the philosophy behind
              <productname>eCos</productname> device drivers, as well as a
              presentation of the C language APIs for using the current
              device drivers. </PARA>
  <para>
    Device driver support includes serial, ethernet and FLASH devices,
    and support for PCI, PCMCIA and USB interconnects.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>RedBoot User's Guide</TERM>
  <LISTITEM>
  <PARA>This describes RedBoot, which provides a complete bootstrap
        environment for a range of embedded operating systems, such as
        embedded Linux and <productname>eCos</productname>, and
        includes facilities such as network downloading and
        debugging. It also provides a simple flash file system for
        boot images.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>TCP/IP Stack Support</TERM>
  <LISTITEM>
  <PARA>This describes the Common Networking for
        <productname>eCos</productname> package, which provides
        support for a complete TCP/IP networking stack. The design
        allows for the actual stack to be modular and at the current
        time two different implementations, one based on OpenBSD from
        2000 and a new version based on FreeBSD, are available.
  </para>
  <para>Other components related to networking, including support for
        SNMP, DNS, HTTP and FTP, are also described.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  </variablelist>

</LISTITEM>
</VARLISTENTRY>

<VARLISTENTRY>
<TERM><EMPHASIS>Component Writer's Guide</EMPHASIS></TERM>
<LISTITEM>
<PARA>The Component Writer's Guide is intended for developers who need
to add or modify parts of <productname>eCos</productname> itself. It
describes the following things:
</PARA>

  <VARIABLELIST>
  <VARLISTENTRY>
  <TERM>Overview</TERM>
  <LISTITEM>
  <PARA>An explanation of the configuration technology used in
  <productname>eCos</productname>, why it is done this way, how it
  works and the terminology used.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>Package Organization</TERM>
  <LISTITEM>
  <PARA>A description of the <productname>eCos</productname> package
  repository, how it is organized and how packages themselves are
  organized.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>The CDL Language</TERM>
  <LISTITEM>
  <PARA>A description of the CDL language and how it is used to
  control the configuration of <productname>eCos</productname>
  components. The document also contains a complete specification of
  the language.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  <VARLISTENTRY>
  <TERM>The Build Process</TERM>
  <LISTITEM>
  <PARA>A description of what happens once a configuration has been
  created and must be built into a set of executables.
  </para>
  </LISTITEM>
  </VARLISTENTRY>

  </variablelist>

</LISTITEM>
</VARLISTENTRY>
</variablelist>

</chapter>


</part>