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<part id="ppp">
<title><productname>eCos</productname> PPP User Guide</title>

<partintro>
<para>
This package provides support for PPP (Point-to-Point Protocol) in the
<productname>eCos</productname> FreeBSD TCP/IP networking stack.
</para>
</partintro>

<!-- {{{ Features                         -->

<chapter id="ppp-features">
<title>Features</title>
<para>
The <productname>eCos</productname> PPP implementation provides the
following features:
</para>
<itemizedlist>

<listitem>
<para>
PPP line protocol including VJ compression.
</para>
</listitem>

<listitem>
<para>
LCP, IPCP and CCP control protocols.
</para>
</listitem>

<listitem>
<para>
PAP and CHAP authentication.
</para>
</listitem>

<listitem>
<para>
CHAT subset connection scripting.
</para>
</listitem>

<listitem>
<para>
Modem control line support.
</para>
</listitem>

</itemizedlist>
</chapter>

<!-- }}} -->
<!-- {{{ Using                            -->

<chapter id="ppp-using">
<title>Using PPP</title>
<para>
Before going into detail, let's look at a simple example of how the
<productname>eCos</productname> PPP package is used. Consider the
following example:
</para>

<programlisting width=72>
static void ppp_up(void)
{
    cyg_ppp_options_t options;
    cyg_ppp_handle_t ppp_handle;

    // Bring up the TCP/IP network
    init_all_network_interfaces();

    // Initialize the options
    cyg_ppp_options_init( &amp;options );

    // Start up PPP
    ppp_handle = cyg_ppp_up( "/dev/ser0", &amp;options );

    // Wait for it to get running
    if( cyg_ppp_wait_up( ppp_handle ) == 0 )
    {
        // Make use of PPP
        use_ppp();

        // Bring PPP link down
        cyg_ppp_down( ppp_handle );

        // Wait for connection to go down.
        cyg_ppp_wait_down( ppp_handle );
    }
}
</programlisting>

<para>
This is a simple example of how to bring up a simple PPP connection to
another computer over a directly connected serial line. The other end
is assumed to already be running PPP on the line and waiting for a
connection.
</para>

<para>
The first thing this code does is to call
<function>init_all_network_interfaces()</function> to bring up the
TCP/IP stack and initialize any other network interfaces. It then
calls <function>cyg_ppp_options_init()</function> to initialize the
PPP options structure to the defaults. As it happens, the default
options are exactly what we want for this example, so we don't need to
make any further changes. We go straight on to bring the PPP interface
up by calling <function>cyg_ppp_up()</function>. The arguments to this
function give the name of the serial device to use, in this case
<literal>"/dev/ser0"</literal>, and a pointer to the options.
</para>

<para>
When <function>cyg_ppp_up()</function> returns, it passes back a
handle to the PPP connection which is to be used in other calls.  The
PPP link will not necessarily have been fully initialized at this
time. There is a certain amount of negotiation that goes on between
the ends of a PPP link before it is ready to pass packets. An
application can wait until the link is ready by calling
<function>cyg_ppp_wait_up()</function>, which returns
zero if the link is up and running, or
<literal>-1</literal> if it has gone down or failed to come up.
</para>

<para>
After a successful return from <function>cyg_ppp_wait_up()</function>,
the application may make use of the PPP connection. This is
represented here by the call to <function>use_ppp()</function> but
it may, of course, be accessed by any thread. While the connection is
up the application may use the standard socket calls to make or accept
network connections and transfer data in the normal way.
</para>

<para>
Once the application has finished with the PPP link, it can bring it
down by calling <function>cyg_ppp_down()</function>. As with bringing
the connection up, this call is asynchronous, it simply informs the
PPP subsystem to start bringing the link down. The application can
wait for the link to go down fully by calling
<function>cyg_ppp_wait_down()</function>.
</para>

<para>
That example showed how to use PPP to connect to a local peer. PPP is
more often used to connect via a modem to a remote server, such as an
ISP. The following example shows how this works:
</para>

<programlisting width=72>

static char *isp_script[] =
{
    "ABORT"             ,       "BUSY"                                  ,
    "ABORT"             ,       "NO CARRIER"                            ,
    "ABORT"             ,       "ERROR"                                 ,
    ""                  ,       "ATZ"                                   ,
    "OK"                ,       "AT S7=45 S0=0 L1 V1 X4 &amp;C1 E1 Q0"      ,
    "OK"                ,       "ATD" CYGPKG_PPP_DEFAULT_DIALUP_NUMBER  ,
    "ogin:--ogin:"      ,       CYGPKG_PPP_AUTH_DEFAULT_USER            ,
    "assword:"          ,       CYGPKG_PPP_AUTH_DEFAULT_PASSWD          ,
    "otocol:"           ,       "ppp"                                   ,
    "HELLO"             ,       "\\c"                                   ,
    0
};

static void ppp_up(void)
{
    cyg_ppp_options_t options;
    cyg_ppp_handle_t ppp_handle;

    // Bring up the TCP/IP network
    init_all_network_interfaces();

    // Initialize the options
    cyg_ppp_options_init( &amp;options );

    options.script = isp_script;
    options.modem  = 1;

    // Start up PPP
    ppp_handle = cyg_ppp_up( "/dev/ser0", &amp;options );

    // Wait for it to get running
    if( cyg_ppp_wait_up( ppp_handle ) == 0 )
    {
        // Make use of PPP
        use_ppp();

        // Bring PPP link down
        cyg_ppp_down( ppp_handle );

        // Wait for connection to go down.
        cyg_ppp_wait_down( ppp_handle );
    }
}
</programlisting>

<para>
The majority of this code is exactly the same as the previous
example. The main difference is in the setting of a couple of options
before calling <function>cyg_ppp_up()</function>. The
<structfield>script</structfield> option is set to point to a CHAT
script to manage the setup of the connection. The
<structfield>modem</structfield> option is set to cause the PPP system
to make use of the modem control lines.
</para>

<para>
During the PPP bring-up a call will be made to
<function>cyg_ppp_chat()</function> to run the CHAT script (see <xref
linkend="ppp-chat">). In the example this script sets up various modem
options and then dials a number supplied as part of the PPP package
configuration (see <xref linkend="ppp-config">). When the connection
has been established, the script log on to the server, using a name
and password also supplied by the configuration, and then starts PPP
on the remote end. If this script succeeds the PPP connection will be
brought up and will then function as expected.
</para>

<para>
The <structfield>modem</structfield> option causes the PPP system to
make use of the modem control lines. In particular it waits for
<literal>Carrier Detect</literal> to be asserted, and will bring the
link down if it is lost. See <xref linkend="ppp-options-init">
for more details.
</para>

</chapter>

<!-- }}} -->
<!-- {{{ Interface                        -->

<chapter id="ppp-interface">
<title>PPP Interface</title>

<!-- {{{ cyg_ppp_options_init             -->

<refentry id="ppp-options-init">

    <refmeta>
    <refentrytitle>cyg_ppp_options_init()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_options_init</refname>
      <refpurpose>Initialize PPP link options</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>cyg_int32 <function>cyg_ppp_options_init</function></funcdef>
          <paramdef>cyg_ppp_options_t <parameter>*options</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-options-init-description">Description</title>
<para>
This function initializes the PPP options, pointed to by the
<parameter>options</parameter> parameter, to the default state. Once
the defaults have been initialized, application code may adjust them
by assigning new values to the the fields of the
<structname>cyg_ppp_options_t</structname> structure.
</para>

<para>
This function returns zero if the options were initialized
successfully. It returns -1 if the <parameter>options</parameter>
argument is NULL, or the options could not be initialized.
</para>

<para>
The option fields, their functions and default values are as follows:
</para>

<variablelist>

<varlistentry>
  <term>debug</term>
  <listitem>
    <para> If set to 1 this enables the reporting of debug messages
    from the PPP system. These will be generated using
    <function>diag_printf()</function> and will appear on the standard
    debug channel. Note that <function>diag_printf()</function>
    disables interrupts during output: this may cause the PPP link
    device to overrun and miss characters. It is quite possible for
    this option to cause errors and even make the PPP link fail
    completely. Consequently, this option should be used with care.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>kdebugflag</term>
  <listitem>
    <para> This five bit field enables low level debugging messages from
    the PPP device layer in the TCP/IP stack. As with the
    <structfield>debug</structfield> option, this may result in missed
    characters and cause errors. The bits of the field have the
    following meanings:
    </para>
    <informaltable frame="all">
      <tgroup cols="3" colsep="1" rowsep="1" align="left">
        <thead>
          <row>
            <entry>Bit</entry>
            <entry>BSD Name</entry>
            <entry>Description</entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>0x01</entry>
            <entry>SC_DEBUG</entry>
            <entry>Enable debug messages</entry>
          </row>
          <row>
            <entry>0x02</entry>
            <entry>SC_LOG_INPKT</entry>
            <entry>Log contents of good packets received</entry>
          </row>
          <row>
            <entry>0x04</entry>
            <entry>SC_LOG_OUTPKT</entry>
            <entry>Log contents of packets sent</entry>
          </row>
          <row>
            <entry>0x08</entry>
            <entry>SC_LOG_RAWIN</entry>
            <entry>Log all characters received</entry>
          </row>
          <row>
            <entry>0x10</entry>
            <entry>SC_LOG_FLUSH</entry>
            <entry>Log all characters flushed</entry>
          </row>
        </tbody>
      </tgroup>
    </informaltable>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>default_route</term>
  <listitem>
    <para> If set to 1 this option causes the PPP subsystem to install
    a default route in the TCP/IP stack's routing tables using the
    peer as the gateway. This entry will be removed when the PPP link
    is broken. If there is already an existing working network
    connection, such as an ethernet device, then there may already be
    a default route established. If this is the case, then this option
    will have no effect.
    </para>
    <para>
    Default value: 1
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>modem</term>
  <listitem>
    <para> If this option is set to 1, then the modem lines will be
    used during the connection. Specifically, the PPP subsystem will
    wait until the <literal>carrier detect</literal> signal is
    asserted before bringing up the PPP link, and will take the PPP
    link down if this signal is de-asserted.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>flowctl</term>
  <listitem>
    <para> This option is used to specify the mechanism used to
    control data flow across the serial line. It can take one of the
    following values:
    </para>
    <variablelist>
      <varlistentry>
        <term><literal>CYG_PPP_FLOWCTL_DEFAULT</literal></term>
        <listitem>
          <para>
          The flow control mechanism is not changed and is left at
          whatever value was set before bringing PPP up. This allows
          a non-standard flow control mechanism to be used, or for it to
          be chosen and set by some other means.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><literal>CYG_PPP_FLOWCTL_NONE</literal></term>
        <listitem>
          <para>
          Flow control is turned off. It is not recommended that this
          option be used unless the baud rate is set low or the two
          communicating machines are particularly fast.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><literal>CYG_PPP_FLOWCTL_HARDWARE</literal></term>
        <listitem>
          <para>
          Use hardware flow control via the RTS/CTS lines. This is the
          most effective flow control mechanism and should always be
          used if available. Availability of this mechanism depends on
          whether the serial device hardware has the ability to control
          these lines, whether they have been connected to the socket
          pins and whether the device driver has the necessary support.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><literal>CYG_PPP_FLOWCTL_SOFTWARE</literal></term>
        <listitem>
          <para>
          Use software flow control by embedding XON/XOFF characters in
          the data stream. This is somewhat less effective that hardware
          flow control since it is subject to the propagation time of
          the serial cable and the latency of the communicating
          devices. Since it does not rely on any hardware support, this
          flow control mechanism is always available.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
    <para>
    Default value: CYG_PPP_FLOWCTL_HARDWARE
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>refuse_pap</term>
  <listitem>
    <para> If this option is set to 1, then the PPP subsystem will not
    agree to authenticate itself to the peer with PAP. When dialling
    in to a remote server it is normal to authenticate the
    client. There are three ways this can be done, using a
    straightforward login mechanism via the CHAT script, with the
    Password Authentication Protocol (PAP), or with the Challenge
    Handshake Authentication Protocol (CHAP). For PAP to work the
    <structfield>user</structfield> and
    <structfield>passwd</structfield> options must be set to the
    expected values. If they are not, then this option should be set
    to force CHAP authentication.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>refuse_chap</term>
  <listitem>
    <para> If this option is set to 1, then the PPP subsystem will not
    agree to authenticate itself to the peer with CHAP. CHAP
    authentication will only work if the
    <structfield>passwd</structfield> option has been set to the
    required CHAP secret for the destination server. Otherwise this
    option should be disabled.
    </para>
    <para>
    If both <structfield>refuse_pap</structfield> and
    <structfield>refuse_chap</structfield> are set, then either no
    authentication will be carried out, or it is the responsibility of
    the <command>chat</command> script to do it. If the peer does not
    require any authentication, then the setting of these options is
    irrelevant.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>baud</term>
  <listitem>
    <para> This option is set to the baud rate at which the serial
    connection should be run. The default value is the rate at which
    modems conventionally operate. This field is an instance of the
    <type>cyg_serial_baud_rate_t</type> enum defined in the
    <literal>serialio.h</literal> header and may only take one of the
    baud rate constants defined in there.
    </para>
    <para>
    Default value: <literal>CYGNUM_SERIAL_BAUD_115200</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>idle_time_limit</term>
  <listitem>
    <para> This is the number of seconds that the PPP connection may
    be idle before it is shut down automatically.
    </para>
    <para>
    Default value: 60
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>maxconnect</term>
  <listitem>
    <para> This causes the connection to terminate when it has been up
    for this number of seconds. The default value of zero means that
    the connection will stay up indefinitely, until either end
    explicitly brings it down, or the link is lost.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>our_address</term>
  <listitem>
    <para> This is the IP address, in network byte order, to be
    attached to the local end of the PPP connection. The default value
    of <literal>INADDR_ANY</literal> causes the local address to be
    obtained from the peer.
    </para>
    <para>
    Default value: <literal>INADDR_ANY</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>his_address</term>
  <listitem>
    <para> This is the IP address, in network byte order, to be
    attached to the remote end of the PPP connection. The default
    value of <literal>INADDR_ANY</literal> causes the remote address
    to be obtained from the peer.
    </para>
    <para>
    Default value: <literal>INADDR_ANY</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>script</term>
  <listitem>
    <para> This is a pointer to a CHAT script suitable for passing to
    <function>cyg_ppp_chat()</function>. See <xref linkend="ppp-chat">
    for details of the format and contents of this script.
    </para>
    <para>
    Default value: <literal>NULL</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>user</term>
  <listitem>
    <para> This array contains the user name to be used for PAP
    authentication. This field is not used for CHAP authentication. By
    default the value of this option is set from the
    <literal>CYGPKG_PPP_AUTH_DEFAULT_USER</literal> configuration
    option.
    </para>
    <para>
    Default value: <literal>CYGPKG_PPP_AUTH_DEFAULT_USER</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>passwd</term>
  <listitem>
    <para> This array contains the password to be used for PAP
    authentication, or the secret to be used during CHAP
    authentication. By default the value of this option is set from
    the <literal>CYGPKG_PPP_AUTH_DEFAULT_PASSWD</literal>
    configuration option.
    </para>
    <para>
    Default value: <literal>CYGPKG_PPP_AUTH_DEFAULT_PASSWD</literal>
    </para>
  </listitem>
</varlistentry>

</variablelist>

    </refsect1>

</refentry>

<!-- }}} -->
<!-- {{{ cyg_ppp_up                       -->

<refentry id="ppp-up">

    <refmeta>
    <refentrytitle>cyg_ppp_up()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_up</refname>
      <refpurpose>Bring PPP connection up</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>cyg_ppp_handle_t <function>cyg_ppp_up</function></funcdef>
          <paramdef>char <parameter>*devnam</parameter></paramdef>
          <paramdef>const cyg_ppp_options_t <parameter>*options</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-up-description">Description</title>
<para>
This function starts up a PPP connection. The
<parameter>devnam</parameter> argument is the name of the device to be
used for the connection, typically <literal>"/dev/ser0"</literal> or
<literal>"/dev/ser1"</literal>. The <structfield>options</structfield>
argument should point to an initialized
<structname>cyg_ppp_options_t</structname> object.
</para>

<para>
The return value will either be zero, indicating a failure, or a
<type>cyg_ppp_handle_t</type> object that may be used as an argument
to other PPP functions.
</para>

<note>
<para>
Although the PPP API is designed to permit several simultaneous
connections to co-exist, at present only one PPP connection is
actually implemented. Any attempt to create a second connection while
there is already one open will fail.
</para>
</note>

</refsect1>

</refentry>

<!-- }}} -->
<!-- {{{ cyg_ppp_down                     -->

<refentry id="ppp-down">

    <refmeta>
    <refentrytitle>cyg_ppp_down()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_down</refname>
      <refpurpose>Bring PPP connection down</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>cyg_int32 <function>cyg_ppp_down</function></funcdef>
          <paramdef>cyg_ppp_handle_t <parameter>handle</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-down-description">Description</title>
<para>
This function brings the PPP connection down. The
<parameter>handle</parameter> argument is the result of a successful
call to <function>cyg_ppp_up()</function>. This function only signals
to the PPP subsystem that the link should be brought down. The link
will be terminated asynchronously. If the application needs to wait
for the link to terminate, then it should call
<function>cyg_ppp_wait_down()</function> after calling
<function>cyg_ppp_down()</function>.
</para>

<para>
The function returns zero if it was able to start the termination of
the PPP connection successfully. It will return -1 if the connection
is not running, or if it could not otherwise start the termination.
</para>

    </refsect1>

</refentry>

<!-- }}} -->  
<!-- {{{ cyg_ppp_wait_up                  -->

<refentry id="ppp-wait-up">

    <refmeta>
    <refentrytitle>cyg_ppp_wait_up()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_wait_up</refname>
      <refpurpose>Wait for PPP connection to come up</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>cyg_int32 <function>cyg_ppp_wait_up</function></funcdef>
          <paramdef>cyg_ppp_handle_t <parameter>handle</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-wait-up-description">Description</title>
<para>
This function waits until the PPP connection is running and then
returns. This is needed because the actual bring up of the connection
happens mostly after the call to <function>cyg_ppp_up()</function>
returns, and may take some time to complete, especially if dialling a
remote server.
</para>

<para>
The result of this call will be zero when the connection is running,
or -1 if the connection failed to start for some reason. If the
connection is already running when this call is made it will return
immediately with a zero result. If the connection is not in the
process of coming up, or has failed, or has terminated, then a result
of -1 will be returned immediately. Thus this function may also be
used to test that the connection is still running at any point.
</para>

    </refsect1>

</refentry>

<!-- }}} -->  
<!-- {{{ cyg_ppp_wait_down                -->

<refentry id="ppp-wait-down">

    <refmeta>
    <refentrytitle>cyg_ppp_wait_down()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_wait_down</refname>
      <refpurpose>Wait for PPP connection to terminate</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>void <function>cyg_ppp_wait_down</function></funcdef>
          <paramdef>cyg_ppp_handle_t <parameter>handle</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-wait-down-description">Description</title>
<para>
This function waits for the PPP connection to terminate. The link may
be terminated with a call to <function>cyg_ppp_down()</function>, by
the remote end, or by the telephone line being dropped or lost. 
</para>

<para>
This function has no return value. If the PPP connection is not
running, or has terminated, it will return. Applications should use
<function>cyg_ppp_wait_up()</function> to test the link state.
</para>

    </refsect1>

</refentry>

<!-- }}} -->  
<!-- {{{ cyg_ppp_chat                     -->

<refentry id="ppp-chat-fn">

    <refmeta>
    <refentrytitle>cyg_ppp_chat()</refentrytitle>
    </refmeta>

    <refnamediv>
      <refname>cyg_ppp_chat</refname>
      <refpurpose>Execute chat script</refpurpose>
    </refnamediv>

    <refsynopsisdiv>
      <funcsynopsis>
        <funcsynopsisinfo>
#include &lt;cyg/ppp/ppp.h&gt;
        </funcsynopsisinfo>
        <funcprototype>
          <funcdef>cyg_int32 <function>cyg_ppp_chat</function></funcdef>
          <paramdef>const char <parameter>*devname</parameter></paramdef>
          <paramdef>const char <parameter>*script[]</parameter></paramdef>
        </funcprototype>
      </funcsynopsis>
    </refsynopsisdiv>

    <refsect1><title id="ppp-chat-description">Description</title>
<para>
This function implements a subset of the automated conversational
scripting as defined by the <command>chat</command> program. The first
argument is the name of the serial device to be used, typically
<literal>"/dev/ser0"</literal> or <literal>"/dev/ser1"</literal>. The
<parameter>script</parameter> argument is a pointer to a zero
terminated array of strings that comprise the chat script. See <xref
linkend="ppp-using"> for an example script, and <xref
linkend="ppp-chat"> for full detail of the script used.
</para>

<para>
Under normal use this function is called from the PPP subsystem if the
<structname>cyg_ppp_options_t</structname>
<structfield>script</structfield> field is set to a
non-<literal>NULL</literal> value. This function should only be used
directly if the application needs to undertake special processing
between running the chat script, and bringing up the PPP connections.
</para>

    </refsect1>

</refentry>

<!-- }}} -->  


<!--IOCTLs???? -->

</chapter>

<!-- }}} -->
<!-- {{{ Install and Config               -->

<chapter id="ppp-config">
<title>Installing and Configuring PPP</title>

<sect1 id="ppp-config-include">
<title>Including PPP in a Configuration</title>

<para>
PPP is contained entirely within a single
<productname>eCos</productname> package. So to include PPP in a
configuration all you need to do is add that package.
</para>

<para>
In the GUI configuration tool use the
<command>Build->Packages</command> menu item, find the "PPP Support"
package in the left-hand pane and use the <command>Add</command> button
to add it to the list of packages in use in the right-hand pane.
</para>

<para>
In the command-line tool <command>ecosconfig</command>, you can use the
following command during the configuration phase to add the PPP package:
</para>

<programlisting width=72>

$ ecosconfig add ppp

</programlisting>

<para>
In addition to the PPP package you will also need to have the
<literal>"Network"</literal> package and the <literal>"Serial Device
Drivers"</literal> package in the configuration. The dependencies and
requirements of the networking package are such that it is strongly
recommended that you start with the <literal>net</literal> template.
</para>

<para>
See the <productname>eCos</productname> User Guide for full details on
how to configure and build <productname>eCos</productname>.
</para>

</sect1>


<sect1 id="ppp-config-config">
<title>Configuring PPP</title>
<para>
The PPP package contains a number of configuration options that may be
changed to affect its behaviour.

<variablelist>

<varlistentry>
  <term>CYGNUM_PPP_PPPD_THREAD_PRIORITY</term>
  <listitem>
    <para>
    The PPP system contains two threads, One is used for receiving
    data from the link and processing control packets.  The other is
    used to transmit data asynchronously to the link when it cannot be
    completed synchronously. The receive thread runs at the priority
    given here, and the transmit thread runs at the next lower
    priority.  The exact priority needed here depends on the
    importance of the PPP subsystem relative to the rest of the
    system. The default is to put it in the middle of the priority
    range to provide reasonable response without impacting genuine
    high priority threads.
    </para>
    <para>
    Default value: <literal>CYGNUM_KERNEL_SCHED_PRIORITIES/2</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_DEBUG_WARN_ONLY</term>
  <listitem>
    <para>
    The runtime <varname>debug</varname> option enables logging of
    high level debug messages. Too many of these can interfere with
    the PPP device and may result in missed messages.  This is because
    these messages are emitted via the diag_printf() mechanism, which
    disables interrupts while it prints.  By default, therefore, we
    only report errors and warnings, and not all events. Setting this
    option to zero will enable the logging of all events.
    </para>
    <para>
    Default value: <literal>1</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_AUTH_DEFAULT_USER</term>
  <listitem>
    <para>
    This option gives the default value for the user name used to
    initialize the <structfield>user</structfield> field in the PPP
    options.
    </para>
    <para>
    Default value: <literal>"eCos"</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_AUTH_DEFAULT_PASSWD</term>
  <listitem>
    <para>
    This option gives the default value for the password used to
    initialize the <structfield>passwd</structfield> field in the PPP
    options.
    </para>
    <para>
    Default value: <literal>"secret"</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_DEFAULT_DIALUP_NUMBER</term>
  <listitem>
    <para>
    This option provides a default dialup number for use in
    <command>chat</command> scripts. This value is not used anywhere
    in the PPP package, but is provided to complete the information
    needed, alongside the user name and password, for accessing a
    typical dialup server.
    </para>
    <para>
    Default value: <literal>"5551234"</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_PAP</term>
  <listitem>
    <para>
    This component enables the inclusion of PAP authentication
    support.
    </para>
    <para>
    Default value: 1
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_CHAP</term>
  <listitem>
    <para>
    This component enables the inclusion of CHAT authentication
    support.
    </para>
    <para>
    Default value: 1
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_COMPRESSION</term>
  <listitem>
    <para>
    This component provides control over PPP compression
    features. WARNING: at present there are problems with this option,
    and and in any case the compression code needs to allocate large
    amounts of memory. Hence this option is currently disabled and
    should remain so.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>PPP_BSDCOMP</term>
  <listitem>
    <para>
    This option enables inclusion of BSD compression into the PPP
    protocol.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>PPP_DEFLATE</term>
  <listitem>
    <para>
    This option enables inclusion of ZLIB compression into the PPP
    protocol.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_CHAT</term>
  <listitem>
    <para>
    This component enables the inclusion of a simple scripting system
    to bring up PPP connections.  It implements a subset of the
    <command>chat</command> scripting language.
    </para>
    <para>
    Default value: 1
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGNUM_PPP_CHAT_ABORTS_MAX</term>
  <listitem>
    <para>
    This option defines the maximum number of <literal>ABORT</literal>
    strings that the CHAT system will store.
    </para>
    <para>
    Default value: 10
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGNUM_PPP_CHAT_ABORTS_SIZE</term>
  <listitem>
    <para>
    This option defines the maximum size of each
    <literal>ABORT</literal> strings that the <command>chat</command>
    system will store.
    </para>
    <para>
    Default value: 20
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGNUM_PPP_CHAT_STRING_LENGTH</term>
  <listitem>
    <para>
    This option defines the maximum size of any expect or reply
    strings that the <command>chat</command> system will be given.
    </para>
    <para>
    Default value: 256
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_TEST_DEVICE</term>
  <listitem>
    <para>
    This option defines the serial device to be used for PPP test
    programs.
    </para>
    <para>
    Default value: <literal>"/dev/ser0"</literal>
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGPKG_PPP_TESTS_AUTOMATE</term>
  <listitem>
    <para>
    This option enables automated testing features in certain test
    programs. These programs will interact with a test server at the
    remote end of the serial link to run a variety of tests in
    different conditions. Without this option most tests default to
    running a single test instance and are suitable for being run by
    hand for debugging purposes.
    </para>
    <para>
    Default value: 0
    </para>
  </listitem>
</varlistentry>

<varlistentry>
  <term>CYGDAT_PPP_TEST_BAUD_RATES</term>
  <listitem>
    <para>
    This option supplies a list of baud rates at which certain tests
    will run if the <literal>CYGPKG_PPP_TESTS_AUTOMATE</literal>
    option is set.
    </para>
    <para>
    Default value: <literal>"CYGNUM_SERIAL_BAUD_19200,CYGNUM_SERIAL_BAUD_38400,CYGNUM_SERIAL_BAUD_57600,CYGNUM_SERIAL_BAUD_115200"</literal>
    </para>
  </listitem>
</varlistentry>

</variablelist>


</para>

</sect1>


</chapter>

<!-- }}} -->
<!-- {{{ Chat                             -->

<chapter id="ppp-chat">
<title>CHAT Scripts</title>
<para>
The automated conversational scripting supported by the
<productname>eCos</productname> PPP package is a subset of the
scripting language provided by the <command>chat</command> command
found on most UNIX and Linux systems.
</para>

<para>
Unlike the <command>chat</command> command, the
<productname>eCos</productname> <function>cyg_ppp_chat()</function>
function takes as a parameter a zero-terminated array of pointers to
strings. In most programs this will be defined by means of an
initializer for a static array, although there is nothing to stop the
application constructing it at runtime. A simple script would be
defined like this:
</para>

<programlisting width=72>

static char *chat_script[] =
{
    "ABORT"        ,  "BUSY"        ,
    "ABORT"        ,  "NO CARRIER"  ,
    ""             ,  "ATD5551234"  ,
    "ogin:--ogin:" ,  "ppp"         ,
    "ssword:"      ,  "hithere"     ,
    0
};

</programlisting>

<para>
The following sections have been abstracted from the public domain
documentation for the <command>chat</command> command. 
</para>


<sect1 id="ppp-chat-script">
<title>Chat Script</title>
<para>
       A script consists of one or more "expect-send" pairs of
       strings, separated by spaces, with an optional "subexpect-
       subsend" string pair, separated by a dash as in the following
       example:
</para>

<programlisting width=72>

    "ogin:--ogin:"     ,  "ppp"       ,
    "ssword:"          ,   "hello2u2" ,
    0

</programlisting>

<para>
       This script fragment indicates that the
       <function>cyg_ppp_chat()</function> function should expect the
       string "ogin:". If it fails to receive a login prompt within
       the time interval allotted, it is to send a carriage return
       to the remote and then expect the string "ogin:" again.  If
       the first "ogin:" is received then the carriage return is not
       generated.
</para>
<para>
       Once it received the login prompt the
       <function>cyg_ppp_chat()</function> function will send the
       string "ppp" and then expect the prompt "ssword:".  When it
       receives the prompt for the password, it will send the password
       "hello2u2".
</para>
<para>
       A carriage return is normally sent following the reply string.
       It is not expected in the "expect" string unless it is
       specifically requested by using the "\r" character sequence.
</para>
<para>
       The expect sequence should contain only what is needed to
       identify the string. It should not contain variable
       information. It is generally not acceptable to look for time
       strings, network identification strings, or other variable
       pieces of data as an expect string.
</para>
<para>
       To help correct for characters which may be corrupted during
       the initial sequence, look for the string "ogin:" rather than
       "login:". It is possible that the leading "l" character may be
       received in error and you may never find the string even though
       it was sent by the system. For this reason, scripts look for
       "ogin:" rather than "login:" and "ssword:" rather than
       "password:".
</para>
<para>
       A very simple script might look like this:
</para>
<programlisting width=72>

    "ogin:"    , "ppp"       ,
    "ssword:"  , " hello2u2" ,
    0

</programlisting>

<para>
       In other words, expect "....ogin:", send "ppp", expect "...ssword:",
       send "hello2u2".
</para>
<para>
       In actual practice, simple scripts are rare. At the very least,
       you should include sub-expect sequences should the original
       string not be received. For example, consider the following
       script:
</para>
<programlisting width=72>

    "ogin:--ogin:"  , "ppp"     ,
    "ssword:"       , "hello2u2",
    0

</programlisting>
<para>
       This would be a better script than the simple one used earlier.
       This would look for the same "login:" prompt, however, if one
       was not received, a single return sequence is sent and then it
       will look for "login:" again. Should line noise obscure the
       first login prompt then sending the empty line will usually
       generate a login prompt again.
</para>

</sect1>

<sect1 id="ppp-chat-abort">
<title>ABORT Strings</title>

<para>
       Many modems will report the status of the call as a
       string. These strings may be CONNECTED or NO CARRIER or
       BUSY. It is often desirable to terminate the script should the
       modem fail to connect to the remote. The difficulty is that a
       script would not know exactly which modem string it may
       receive. On one attempt, it may receive BUSY while the next
       time it may receive NO CARRIER.
</para>
<para>
       These "abort" strings may be specified in the script using
       the ABORT sequence. It is written in the script as in  the
       following example:
</para>
<programlisting width=72>

    "ABORT"    , "BUSY"    ,
    "ABORT"    , "NO CARRIER"  ,
    ""         , "ATZ"         ,
    "OK"       , "ATDT5551212" ,
    "CONNECT"  , ...

</programlisting>

<para>
       This sequence will expect nothing; and then send the string
       ATZ.  The expected response to this is the string OK. When it
       receives OK, it sends the string ATDT5551212 to dial the
       telephone.  The expected string is CONNECT. If the string
       CONNECT is received the remainder of the script is
       executed. However, should the modem find a busy telephone, it
       will send the string BUSY. This will cause the string to match
       the abort character sequence. The script will then fail because
       it found a match to the abort string. If it received the string
       NO CARRIER, it will abort for the same reason. Either string
       may be received. Either string will terminate the chat script.
</para>

</sect1>

<sect1 id="ppp-chat-timeout">
<title>TIMEOUT</title>
<para>
       The initial timeout value  is  45  seconds.
       To  change  the  timeout value for the next expect string,
       the following example may be used:
</para>
<programlisting width=72>

    ""              , "ATZ"         ,
    "OK"            , "ATDT5551212" ,
    "CONNECT"       , "\\c"         ,
    "TIMEOUT"       , "10"          ,
    "ogin:--ogin:"  , "ppp"         ,
    "TIMEOUT"       , "5"           ,
    "assword:"      , "hello2u2"    ,
    0

</programlisting>
<para>
       This will change the timeout to 10 seconds when it expects the
       login: prompt. The timeout is then changed to 5 seconds when
       it looks for the password prompt.
</para>
<para>
       The  timeout,  once changed, remains in effect until it is
       changed again.
</para>

</sect1>

<sect1 id="ppp-chat-eot">
<title>Sending EOT</title>
<para>
       The special reply string of EOT indicates  that  the  chat
       program  should  send an EOT character to the remote. This
       is normally the End-of-file character sequence.  A  return
       character is not sent following the EOT.  The EOT sequence
       may be embedded into the send string  using  the  sequence
       "\x04" (i.e. a Control-D character).
</para>
</sect1>

<sect1 id="ppp-chat-escape">
<title>Escape Sequences</title>
<para>
Most standard <command>chat</command> escape sequences can be replaced
with standard C string escapes such as '\r', '\n', '\t'
etc. Additional escape sequences may be embedded in the expect or
reply strings by introducing them with <emphasis>two</emphasis>
backslashes.
</para>

<variablelist>

<varlistentry>
<term>\\c</term>
<listitem>
<para>
Suppresses the newline at the end of the reply string.  This is the
only method to send a string without a trailing return character. It
must be at the end of the send string.  For example, the sequence
"hello\\c" will simply send the characters h, e, l, l, o.  (not valid
in expect strings.)
</para>
</listitem>
</varlistentry>

</variablelist>

</sect1>

</chapter>

<!-- }}} -->
<!-- {{{ Drivers                          -->

<chapter id="ppp-drivers">
<title>PPP Enabled Device Drivers</title>
<para>
For PPP to function fully over a serial device, its driver must
implement certain features. At present not all
<productname>eCos</productname> serial drivers implement these
features. A driver indicates that it supports a certain feature by
including an <literal>"implements"</literal> line in its CDL for the
following interfaces:
</para>

<variablelist>

<varlistentry>
<term><literal>CYGINT_IO_SERIAL_FLOW_CONTROL_HW</literal></term>
<listitem>
<para>
This interface indicates that the driver implements hardware flow
control using the RTS and CTS lines. When data is being transferred
over high speed data lines, it is essential that flow control be used
to prevent buffer overrun.
</para>
<para>
The PPP subsystem functions best with hardware flow control. If this
is not available, then it can be configured to use software flow
control. Since software flow control is implemented by the device
independent part of the serial device infrastructure, it is available
for all serial devices. However, this will have an effect on the
performance and reliability of the PPP link.
</para>
</listitem>
</varlistentry>


<varlistentry>
<term><literal>CYGINT_IO_SERIAL_LINE_STATUS_HW</literal></term>
<listitem>
<para>
This interface indicates that the driver implements a callback
interface for indicating the status of various RS232 control lines. Of
particular interest here is the ability to detect changes in the
Carrier Detect (CD) line. Not all drivers that implement this
interface can indicate CD status.
</para>
<para>
This functionality is only needed if it is important that the link be
dropped immediately a telephone connection fails. Without it, a
connection will only be dropped after it times out. This may be
acceptable in many situations.
</para>
</listitem>
</varlistentry>

</variablelist>

<para>
At the time of writing, the serial device drivers for the following
platforms implement some or all of the required functionality:
</para>

<itemizedlist>

<listitem>
<para>
All drivers that use the generic 16x5x driver implement all functions:
</para>
<itemizedlist>
<listitem><para>ARM CerfPDA</para></listitem>
<listitem><para>ARM IQ80321</para></listitem>
<listitem><para>ARM PID</para></listitem>
<listitem><para>ARM IOP310</para></listitem>
<listitem><para>i386 PC</para></listitem>
<listitem><para>MIPS Atlas</para></listitem>
<listitem><para>MIPS Ref4955</para></listitem>
<listitem><para>SH3 SE77x9</para></listitem>
</itemizedlist>
</listitem>

<listitem>
<para>
The following drivers implement flow control but either do not support
line status callbacks, or do not report CD changes:
</para>
<itemizedlist>
<listitem><para>SH4 SCIF</para></listitem>
<listitem><para>A&amp;M AdderI</para></listitem>
<listitem><para>A&amp;M AdderII</para></listitem>
</itemizedlist>
</listitem>

<listitem>
<para>
All other drivers can support software flow control only.
</para>
</listitem>

</itemizedlist>


</chapter>

<!-- }}} -->
<!-- {{{ Tests                            -->

<chapter id="ppp-tests">
<title>Testing</title>


<sect1>
<title>Test Programs</title>

<para>
There are a number of test programs supplied with the PPP
subsystem. By default all of these tests use the device configured by
<literal>CYGPKG_PPP_TEST_DEVICE</literal> as the PPP link device.
</para>

<variablelist>

<varlistentry>
<term><literal>ppp_up</literal></term>
<listitem>
<para>
This test just brings up the PPP link on
<literal>CYGPKG_PPP_TEST_DEVICE</literal> and waits until the remote end brings
it back down. No modem lines are used and the program expects a PPP
connection to be waiting on the other end of the line. Typically the
remote end will test the link using <command>ping</command> or access
the HTTP system monitor if it is present.
</para>
<para>
If <literal>CYGPKG_PPP_TESTS_AUTOMATE</literal> is set, then this test
attempts to bring PPP up at each of the baud rates specified in
<literal>CYGDAT_PPP_TEST_BAUD_RATES</literal>. If it is not set then
it will just bring the connection up at 115200 baud.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>ppp_updown</literal></term>
<listitem>
<para>
This test brings the PPP link up on
<literal>CYGPKG_PPP_TEST_DEVICE</literal> and attempts to
<command>ping</command> the remote end of the link. Once the pings
have finished, the link is then brought down.
</para>
<para>
If <literal>CYGPKG_PPP_TESTS_AUTOMATE</literal> is set, then this test
attempts to bring PPP up at each of the baud rates specified in
<literal>CYGDAT_PPP_TEST_BAUD_RATES</literal>. If it is not set then
it will just bring the connection up at 115200 baud.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>chat</literal></term>
<listitem>
<para>
This test does not bring the PPP link up but simply executes a chat
script. It expects a server at the remote end of the link to supply
the correct responses.
</para>
<para>
This program expects the <command>test_server.sh</command> script to
be running on the remote end and attempts several different tests,
expecting a variety of different responses for each.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>ppp_auth</literal></term>
<listitem>
<para>
This test attempts to bring up the PPP link under a variety of
different authentication conditions. This includes checking that both
PAP and CHAP authentication work, and that the connection is rejected
when the incorrect authentication protcol or secrets are used. 
</para>
<para>
This test expects the <command>test_server.sh</command> script to be
running on the remote end. For this test to work the <filename>/etc/ppp/pap-secrets</filename> file on the remote
end should contain the following two lines:
</para>
<programlisting width=72>
eCos       *         secret       *
eCosPAP    *         secretPAP    *
</programlisting>
<para>
The <filename>/etc/ppp/chap-secrets</filename> file should contain:
</para>
<programlisting width=72>
eCos       *         secret       *
eCosCHAP   *         secretCHAP   *
</programlisting>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>isp</literal></term>
<listitem>
<para>
This test expects the serial test device to be connected to a Hayes
compatible modem. The test dials the telephone number given in
<literal>CYGPKG_PPP_DEFAULT_DIALUP_NUMBER</literal> and attempts to
log on to an ISP using the user name and password supplied in
<literal>CYGPKG_PPP_AUTH_DEFAULT_USER</literal> and
<literal>CYGPKG_PPP_AUTH_DEFAULT_PASSWD</literal>. Once the PPP
connection has been made, the program then attempts to ping a number
of well known addresses.
</para>
<para>
Since this test is designed to interact with an ISP, it does not run
within the automated testing system.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>tcp_echo</literal></term>
<listitem>
<para>
This is a version of the standard network <command>tcp_echo</command>
test that brings up the PPP connection before waiting for the
<command>tcp_sink</command> and <command>tcp_source</command> programs
to connect. It is expected that at least one of these programs will
connect via the PPP link. However, if another network interface is
present, such as an ethernet device, then one may connect via that
interface.
</para>
<para>
While this test is supported by the <command>test_server.sh</command>
script, it runs for such a long time that it should not normally be
used during automated testing.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>nc_test_slave</literal></term>
<listitem>
<para>
This is a version of the standard network
<command>nc_test_slave</command> test that brings up the PPP
connection before waiting for the <command>nc_test_master</command>
program to connect. It is expected that the master will connect via
the PPP link.
</para>
<para>
While this test is supported by the <command>test_server.sh</command>
script, it runs for such a long time that it should not normally be
used during automated testing.
</para>
</listitem>
</varlistentry>

</variablelist>

</sect1>

<sect1 id="ppp-test-script">
<title>Test Script</title>

<para>
The PPP package additionally contains a shell script
(<command>test_server.sh</command>) that may be used to operate the
remote end of a PPP test link.
</para>

<para>
The script may be invoked with the following arguments:
</para>

<variablelist>

<varlistentry>
<term><literal>--dev=&lt;devname&gt;</literal></term>
<listitem>
<para>
This mandatory option gives the name of the device to be used for the
PPP link. Typically <literal>"/dev/ttyS0"</literal> or
<literal>"/dev/ttyS1"</literal>.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--myip=&lt;ipaddress&gt;</literal></term>
<listitem>
<para>
This mandatory option gives the IP address to be attached to this end
of the PPP link.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--hisip=&lt;ipaddress&gt;</literal></term>
<listitem>
<para>
This mandatory option gives the IP address to be attached to the
remote (test target) end of the PPP link.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--baud=&lt;baud_rate&gt;</literal></term>
<listitem>
<para>
This option gives the baud rate at which the PPP link is to be run. If
absent then the link will run at the value set for
<literal>--redboot-baud</literal>.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--redboot</literal></term>
<listitem>
<para>
If this option is present then the script will look for a
<literal>"RedBoot&gt;"</literal> prompt between test runs. This is
necessary if the serial device being used for testing is also used by
RedBoot.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--redboot-baud=&lt;baud_rate&gt;</literal></term>
<listitem>
<para>
This option gives the baud rate at which the search for the RedBoot
prompt will be made. If absent then the link will run at 38400 baud.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><literal>--debug</literal></term>
<listitem>
<para>
If this option is present, then the script will print out some
additional debug messages while it runs.
</para>
</listitem>
</varlistentry>

</variablelist>

<para>
This script operates as follows: If the <literal>--redboot</literal>
option is set it sets the device baud rate to the RedBoot baud rate
and waits until a <literal>"RedBoot&gt;"</literal> prompt is encountered.
It then sets the baud rate to the value given by the
<literal>--baud</literal> option and reads lines from the device until
a recognizable test announce string is read. It then executes an
appropriate set of commands to satisfy the test. This usually means
bringing up the PPP link by running <command>pppd</command> and maybe
executing various commands. It then either terminates the link itself,
or waits for the target to terminate it. It then goes back to looking
for another test announce string. If a string of the form
<literal>"BAUD:XXX"</literal> is received then the baud rate is
changed depending on the <literal>XXX</literal> value. If a
<literal>"FINISH"</literal> string is received it returns to waiting
for a <literal>"RedBoot>"</literal> prompt. The script repeats this
process until it is terminated with a signal.
</para>

</sect1>

</chapter>

<!-- }}} -->


</part>