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<part id="redboot"><beginpage>
<title>RedBoot&trade; User's Guide</title>
<toc id="Getting-Started-with-Redboot2"></toc>
<chapter id="Getting-Started-with-RedBoot">
<title>Getting Started with RedBoot</title>
<para><indexterm><primary>Red Boot</primary><secondary>getting started</secondary>
</indexterm>RedBoot&trade; is an acronym for "Red Hat Embedded Debug and Bootstrap",
and is the standard embedded system debug/bootstrap environment from Red Hat,
replacing the previous generation of debug firmware: <indexterm><primary>CygMon</primary>
</indexterm>CygMon and <indexterm><primary>GDB stubs</primary></indexterm>GDB
stubs. It provides a complete bootstrap environment for a range of embedded
operating systems, such as embedded Linux&trade; and eCos&trade;, and includes facilities
such as network downloading and debugging. It also provides a simple flash
file system for boot images.</para>
<para>RedBoot provides a wide set of tools for downloading and executing programs
on embedded target systems, as well as tools for manipulating the target system's
environment. It can be used for both product development (debug support) and
for end product deployment (flash and network booting).</para>
<para>Here are some highlights of <indexterm><primary>RedBoot's capabilities
</primary></indexterm>RedBoot&rsquo;s capabilities:  </para>
<itemizedlist>
<listitem><para>Boot scripting support</para>
</listitem>
<listitem><para>Simple command line interface for RedBoot configuration and
management, accessible via serial (terminal) or Ethernet (telnet) </para>
</listitem>
<listitem><para>Integrated GDB stubs for connection to a host-based debugger
via serial or ethernet. (Ethernet connectivity is limited to local network
only)</para>
</listitem>
<listitem><para>Attribute Configuration - user control of aspects such as
system time and date (if applicable), default Flash image to boot from, default
failsafe image, static IP address, etc.</para>
</listitem>
<listitem><para>Configurable and extensible, specifically adapted to the target
environment </para>
</listitem>
<listitem><para>Network bootstrap support including setup and download, via
BOOTP, DHCP and TFTP</para>
</listitem>
<listitem><para>X/YModem support for image download via serial</para>
</listitem>
<listitem><para>Power On Self Test</para>
</listitem>
</itemizedlist>
<para>Although RedBoot is derived from eCos, it may be used as a generalized
system debug and bootstrap control software for any embedded system and any
operating system. For example, with appropriate additions, RedBoot could replace
the commonly used BIOS of PC (and certain other) architectures. Red Hat is
currently installing RedBoot on all embedded platforms as a standard practice,
and RedBoot is now generally included as part of all Red Hat Embedded Linux
and eCos ports. Users who specifically wish to use RedBoot with the eCos operating
system should refer to the <emphasis>Getting Started with eCos</emphasis>
document, which provides information about the portability and extendability
of RedBoot in an eCos environment.</para>
<sect1 id="redboot-on-the-web">
<title>More information about RedBoot on the web</title>
<para>
<para>The <ulink url="http://sources.redhat.com/redboot/">RedBoot Net
Distribution web site</ulink> contains downloadable sources and documentation
for all publically released targets, including the latest features and updates.
</para>
</sect1>
<sect1 id="installing-redboot">
<title>Installing RedBoot</title>
<para><indexterm><primary>installing RedBoot</primary><secondary>general procedures
</secondary></indexterm><indexterm><primary>RedBoot installation</primary>
<secondary>general procedures</secondary></indexterm>To install the RedBoot
package, follow the procedures detailed in the accompanying README. </para>
<para>Although there are other possible configurations, RedBoot is usually
run from the target platform&rsquo;s flash boot sector or boot ROM, and is
designed to run when your system is initially powered on. The method used
to install the RedBoot image into non-volatile storage varies from platform
to platform. In general, it requires that the image be programmed into flash
in situ or programmed into the flash or ROM using a device programmer. In
some cases this will be done at manufacturing time; the platform being delivered
with RedBoot already in place. In other cases, you will have to program RedBoot
into the appropriate device(s) yourself. Installing to flash in situ may require
special cabling or interface devices and software provided by the board manufacturer.
The details of this installation process for a given platform will be found
in Installation and Testing. Once installed, user-specific configuration options
may be applied, using the <command>fconfig</command> command,
providing that persistent data storage in flash is present in the relevant
RedBoot version. See <xref linkend="Configuring-the-RedBoot-Environment">
for details.</para>
</sect1>
<sect1 id="user-interface">
<title>User Interface</title>
<para><indexterm><primary>user interface</primary></indexterm><indexterm>
<primary>ui</primary></indexterm><indexterm><primary>cli</primary></indexterm>RedBoot
provides a command line user interface (CLI). At the minimum, this interface
is normally available on a serial port on the platform. If more than one serial
interface is available, RedBoot is normally configured to try to use any one
of the ports for the CLI. Once command input has been received on one port,
that port is used exclusively until the board is reset or the channel
is manually changed by the
user. If the platform has networking
capabilities, the RedBoot CLI is also accessible using the <computeroutput>
telnet</computeroutput> access protocol. By default, RedBoot runs <computeroutput><indexterm>
<primary>telnet</primary></indexterm>telnet</computeroutput> on port TCP/9000,
but this is configurable and/or settable by the user. </para>
<para>RedBoot also contains a set of <indexterm><primary>GDB stubs</primary>
</indexterm>GDB "stubs", consisting of code which supports the GDB remote
protocol. GDB stub mode is automatically invoked when the '$' character appears
anywhere on a command line unless escaped using the '\' character. 
The platform will remain in GDB
stub mode until explicitly disconnected (via the GDB protocol). The GDB stub
mode is available regardless of the connection method; either serial or network.
Note that if a GDB connection is made via the network, then special care must
be taken to preserve that connection when running user code. eCos contains
special network sharing code to allow for this situation, and can be used
as a model if this methodology is required in other OS environments.</para>
</sect1>

<sect1 id="RedBoot-Editing-Commands">
<title>RedBoot Editing Commands</title>
<para><indexterm><primary>RedBoot</primary><secondary>editing commands</secondary>
</indexterm><indexterm><primary>editing commands</primary></indexterm><indexterm>
<primary>commands</primary><secondary>editing</secondary></indexterm>RedBoot
uses the following line editing commands. 
<note><title>NOTE</title>
<para>
In this description, <guibutton>^A</guibutton> means the character formed
by typing the letter &ldquo;A&rdquo; while holding down the control key.
</para></note>
<itemizedlist>
<listitem><para><guibutton>Delete</guibutton> (0x7F) or 
<guibutton>Backspace</guibutton> (0x08) 
erases the character to the left of the cursor.
</para></listitem>
<listitem><para>
<guibutton>^A</guibutton>
moves the cursor (insertion point) to the beginning of the line.
</para></listitem>
<listitem><para>
<guibutton>^K</guibutton>
erases all characters on the line from the cursor to the end.
</para></listitem>
<listitem><para>
<guibutton>^E</guibutton>
positions the cursor to the end of the line.
</para></listitem>
<listitem><para>
<guibutton>^D</guibutton>
erases the character under the cursor.
</para></listitem>
<listitem><para>
<guibutton>^F</guibutton>
moves the cursor one character to the right.
</para></listitem>
<listitem><para>
<guibutton>^B</guibutton>
moves the cursor one character to the left.
</para></listitem>
<listitem><para>
<guibutton>^P</guibutton>
replaces the current line by a previous line from the history buffer.  
A small number of lines
can be kept as history.  Using ^P (and ^N), the current line can be replaced
by any one of the previously typed lines.
</para></listitem>
<listitem><para>
<guibutton>^N</guibutton>
replaces the current line by the next line from the history buffer.  
</para></listitem>
</itemizedlist></para>
<para>In the case of the <command>fconfig</command>
command, additional editing commands are possible. 
As data are entered for this command, the current/previous value
will be displayed and the cursor placed at the end of that data.
The user may use the editing keys (above) to move around in the data
to modify it as appropriate.
Additionally, when certain
characters are entered at the end of the current value, 
i.e. entered separately, certain behavior is elicited.</para>
<para><itemizedlist>
<listitem>
<para>^ (caret) switch to editing the previous item in the 
<command>fconfig</command> list. If fconfig edits item A, followed by item B,
pressing ^ when changing item B, allows you to change item A. This is similar
to the up arrow.
Note: ^P and ^N do not have the same meaning while editing 
<command>fconfig</command> data and should not be used.
</para>
</listitem>
<listitem><para>. (period) stop editing any further items. This does not change
the current item.</para>
</listitem>
<listitem><para><guibutton>Return</guibutton> leaves the value
for this item unchanged. Currently it is not possible to step through the
value for the start-up script; it must always be retyped.</para>
</listitem>
</itemizedlist></para>
</sect1>

<sect1 id="startup-mode">
<title>RedBoot Startup Mode</title>
<para>
  <indexterm><primary>RedBoot</primary><secondary>mode</secondary></indexterm>
  <indexterm><primary>RedBoot</primary><secondary>startup mode</secondary></indexterm>
</para>

<para>RedBoot can normally be configured to run in a number of startup
modes (or just "modes" for short), determining its location of
residence and execution:
<variablelist>
 <varlistentry><term>ROM mode</term>
 <listitem><para>In this mode, RedBoot both resides and executes from
 ROM memory (flash or EPROM). This mode is used when there are limited
 RAM resources. The flash commands cannot update the region of flash
 where the RedBoot image resides. In order to update the RedBoot image
 in flash, it is necessary to run a RAM mode instance of
 RedBoot.</para></listitem>
 </varlistentry>

 <varlistentry><term>ROMRAM mode</term>
 <listitem><para>In this mode, RedBoot resides in ROM memory (flash or
 EPROM), but is copied to RAM memory before it starts executing. The
 RAM footprint is larger than for ROM mode, but there are two
 advantages to make up for this: it normally runs faster (relevant
 only on slower boards) and it is able to update the flash region
 where the image resides.</para></listitem>
 </varlistentry>

 <varlistentry><term>RAM mode</term>
 <listitem><para>In this mode, RedBoot both resides and executes from
 RAM memory. This is used for updating a primary ROM
 mode image in situ and sometimes as part of the RedBoot installation
 on the board when there's already an existing (non-RedBoot) boot
 monitor available.</para>

 <para> You can only use ROM and ROMRAM mode images for booting a
 board - a RAM mode image cannot run unless loaded by another ROM
 monitor. There is no need for this startup mode if a RedBoot ROMRAM
 mode image is the primary boot monitor.  When this startup mode is
 programmed into flash (as a convenience as it's fast to load from
 flash) it will generally be named as "RedBoot[RAM]" in the FIS
 directory.  </para></listitem>
 </varlistentry>
</variablelist>

The chosen mode has influence on flash and RAM resource usage (see
<xref linkend="resource-usage">) and the procedure of an in situ update
of RedBoot in flash (see <xref linkend="Updating-Redboot">).</para>

<para>The startup mode is controlled by the option CYG_HAL_STARTUP
which resides in the platform HAL. Some platforms provide only some of
the RAM, ROM, and ROMRAM modes, others provide additional
modes.</para>

<para>To see mode of a currently executing RedBoot, issue the
<command>version</command> command, which prints the RedBoot banner,
including the startup mode (here ROM):
<screen>RedBoot><userinput>version</userinput>

RedBoot(tm) bootstrap and debug environment <emphasis>[ROM]</emphasis>
Non-certified release, version UNKNOWN - built 13:31:57, May 17 2002
</screen>
</para>

</sect1>

<sect1 id="resource-usage">
<title>RedBoot Resource Usage</title>
<para>
  <indexterm><primary>RedBoot</primary><secondary>resource usage</secondary></indexterm>
</para>

<para>RedBoot takes up both flash and RAM resources depending on its
startup mode and number of enabled features. There are also other
resources used by RedBoot, such as timers. Platform-specific resources
used by RedBoot are listed in the platform specific parts of this
manual.</para>

<para>Both flash and RAM resources used by RedBoot depend to some
degree on the features enabled in the RedBoot configuration. It is
possible to reduce in particular the RAM resources used by RedBoot by
removing features that are not needed. Flash resources can also be
reduced, but due to the granularity of the flash (the block sizes),
reductions in feature size do not always result in flash resource
savings.</para>


<sect2>
<title>Flash Resources</title>
<para>On many platforms, a ROM mode RedBoot image resides in the first
flash sectors, working as the board's primary boot monitor. On these
platforms, it is also normal to reserve a similar amount of flash for
a secondary RAM mode image, which is used when updating the primary
ROM mode image.</para>
<para>On other platforms, a ROMRAM mode RedBoot image is used as the
primary boot monitor. On these platforms there is not normally
reserved space for a RAM mode RedBoot image, since the ROMRAM mode
RedBoot is capable of updating the primary boot monitor image.</para>
<para>Most platforms also contain a FIS directory (keeping track of
available flash space) and a RedBoot config block (containing RedBoot
board configuration data).</para>
<para>To see the amount of reserved flash memory, run the <command>fis
list</command> command:
<screen>RedBoot> <userinput>fis list</userinput>
Name              FLASH addr  Mem addr    Length      Entry point
RedBoot           0x00000000  0x00000000  0x00020000  0x00000000
RedBoot[RAM]      0x00020000  0x06020000  0x00020000  0x060213C0
RedBoot config    0x0007F000  0x0007F000  0x00001000  0x00000000
FIS directory     0x00070000  0x00070000  0x0000F000  0x00000000
</screen>
</para>

<para>To save flash resources, use a ROMRAM mode RedBoot, or if using
a ROM mode RedBoot, avoid reserving space for the RedBoot[RAM] image
(this is done by changing the RedBoot configuration) and download the
RAM mode RedBoot whenever it is needed. If the RedBoot image takes up
a fraction of an extra flash block, it may be possible to reduce the
image size enough to free this block by removing some features.</para>

</sect2>

<sect2>
<title>RAM Resources</title>

<para>RedBoot reserves RAM space for its run-time data, and such
things as CPU exception/interrupt tables. It normally does so at the
bottom of the memory map. It may also reserve space at the top of the
memory map for configurable RedBoot features such as the net stack
and zlib decompression support.</para>
<para>To see the actual amount of reserved space, issue the
<command>version</command> command, which prints the RedBoot banner,
including the RAM usage:
<screen>RedBoot> <userinput>version</userinput>

RedBoot(tm) bootstrap and debug environment [ROM]
Non-certified release, version UNKNOWN - built 13:31:57, May 17 2002

Platform: FooBar (SH 7615)
Copyright (C) 2000, 2001, 2002, Red Hat, Inc.

<emphasis>RAM: 0x06000000-0x06080000, 0x06012498-0x06061000 available</emphasis>
FLASH: 0x00000000 - 0x00080000, 8 blocks of 0x00010000 bytes each.
</screen>
</para>

<para>To simplify operations that temporarily need data in free
memory, the limits of free RAM are also available as aliases (aligned
to the nearest kilo-byte limit). These are named
<indexterm><primary>FREEMEMLO</primary></indexterm>FREEMEMLO and
<indexterm><primary>FREEMEMHI</primary></indexterm>FREEMEMHI, and can
be used in commands like any user defined alias:
<screen>RedBoot> <userinput>load -r -b %{FREEMEMLO} file</userinput>
Raw file loaded 0x06012800-0x06013e53, assumed entry at 0x06012800
</screen>
<screen>
RedBoot> <userinput>x -b %{FREEMEMHI}</userinput>
06061000: 86 F5 EB D8 3D 11 51 F2  96 F4 B2 DC 76 76 8F 77  |....=.Q.....vv.w|
06061010: E6 55 DD DB F3 75 5D 15  E0 F3 FC D9 C8 73 1D DA  |.U...u]......s..|
</screen>
</para>

<para>To reduce RedBoot's RAM resource usage, use a ROM mode
RedBoot. The RedBoot features that use most RAM are the net stack, the
flash support and the gunzip support. These, and other features, can
be disabled to reduce the RAM footprint, but obviously at the cost of
lost functionality.</para>

</sect2>
</sect1>

<sect1 id="Configuring-the-RedBoot-Environment">
<title>Configuring the RedBoot Environment</title>
<para><indexterm><primary>configuring the RedBoot environment</primary><secondary></secondary>
</indexterm><indexterm><primary>RedBoot </primary><secondary>environment configuration
</secondary></indexterm><indexterm><primary>environment configuration</primary>
</indexterm>Once installed, RedBoot will operate fairly generically. However,
there are some features that can be configured for a particular installation.
These depend primarily on whether <indexterm><primary>flash and/or networking
support</primary></indexterm><indexterm><primary>networking and/or flash support
</primary></indexterm>flash and/or networking support are available. The remainder
of this discussion assumes that support for both of these options is included
in RedBoot.</para>
<sect2 id=target-network-configuration>
<title>Target Network Configuration</title>
<para><indexterm><primary>target network configuration</primary></indexterm><indexterm>
<primary>network configuration</primary></indexterm><indexterm><primary>configuration
</primary><secondary>secondary</secondary></indexterm>Each node in a networked
system needs to have a unique address. Since the network support in RedBoot
is based on <indexterm><primary>TCP/IP</primary></indexterm>TCP/IP, this address
is an IP (Internet Protocol) address. <indexterm><primary>IP address type
</primary></indexterm>There are two ways for a system to &ldquo;know&rdquo;
its IP address. First, it can be stored locally on the platform. This is known
as having a static IP address. Second, the system can use the network itself
to discover its IP address. This is known as a dynamic IP address. RedBoot
supports this dynamic IP address mode by use of the <indexterm><primary>BOOTP
</primary></indexterm>BOOTP (a subset of <indexterm><primary>DHCP</primary>
</indexterm>DHCP) protocol. In this case, RedBoot will ask the network (actually
some generic server on the network) for the IP address to use.</para>
<note><title>NOTE</title>
<para>Currently, RedBoot only supports BOOTP. In future releases, DHCP may
also be supported, but such support will be limited to additional data items,
not lease-based address allocation.</para>
</note>
<para>The choice of <indexterm><primary>IP address type</primary></indexterm>IP
address type is made via the <indexterm><primary>fconfig command</primary>
</indexterm><command>fconfig</command> command. Once a selection
is made, it will be stored in flash memory. RedBoot only queries the flash
configuration information at reset, so any changes will require restarting
the platform.</para>
<para>Here is an example of the RedBoot <command>fconfig</command>
command, showing network addressing:    </para>
<programlisting>RedBoot> <userinput>fconfig -l</userinput>
Run script at boot: false
Use BOOTP for network configuration: false
Local IP address: 192.168.1.29
Default server IP address: 192.168.1.101
DNS server IP address: 192.168.1.1
GDB connection port: 9000
Network debug at boot time: false  </programlisting>
<para>In this case, the board has been configured with a static IP address
listed as the Local IP address. The default server IP address specifies which
network node to communicate with for TFTP service. This address can be overridden
directly in the <indexterm><primary>TFTP commands</primary></indexterm>TFTP
commands.</para>
<para>The <computeroutput>DNS server IP address</computeroutput> option
controls where RedBoot should make DNS lookups<indexterm><primary>DNS
lookups</primary></indexterm>. A setting of 0.0.0.0 will disable DNS
lookups. The DNS server IP address can also be set at runtime.</para>
<para>If the selection for <computeroutput>Use BOOTP for network configuration
</computeroutput> had been <computeroutput>true</computeroutput>, these IP
addresses would be determined at boot time, via the BOOTP protocol. The final
number which needs to be configured, regardless of IP address selection mode,
is the <indexterm><primary>GDB connection port</primary></indexterm><computeroutput>
GDB connection port</computeroutput>. RedBoot allows for incoming commands
on either the available serial ports or via the network. This port number
is the TCP port that RedBoot will use to accept incoming connections.  </para>
<para>These connections can be used for GDB sessions, but they can also be
used for generic RedBoot commands. In particular, it is possible to communicate
with RedBoot via the <indexterm><primary>telnet</primary></indexterm>telnet
protocol. For example, on Linux&reg;: </para>
<programlisting>% telnet redboot_board 9000
Connected to redboot_board
Escape character is &lsquo;^]&rsquo;.
RedBoot>  </programlisting>
</sect2>
<sect2>
<title>Host Network Configuration</title>
<para><indexterm><primary>host network configuration</primary></indexterm><indexterm>
<primary>network configuration</primary><secondary>host</secondary></indexterm><indexterm>
<primary>configuration</primary><secondary>network</secondary></indexterm>RedBoot
may require three different classes of service from a network host:   </para>
<itemizedlist>
<listitem><para>dynamic IP address allocation, using BOOTP   </para>
</listitem>
<listitem><para>TFTP service for file downloading </para>
</listitem>
<listitem><para>DNS server for hostname lookups </para>
</listitem>
</itemizedlist>
<para>Depending on the host system, these services may or may not be available
or enabled by default. See your system documentation for more details.</para>
<para>In particular, on Red Hat Linux, neither of these services will be configured
out of the box. The following will provide a limited explanation of how to
set them up. These configuration setups must be done as <computeroutput>root
</computeroutput> on the host or server machine.</para>
<sect3>
<title>Enable TFTP on Red Hat Linux 6.2</title>
<procedure>
<step><para><indexterm><primary>TFTP</primary><secondary>enabling on Red Hat
Linux 6.2</secondary></indexterm><indexterm><primary>Red Hat Linux</primary>
<secondary>enabling TFTP on version 6.2</secondary></indexterm>Ensure that
you have the tftp-server RPM package installed. By default, this installs
the TFTP server in a disabled state. These steps will enable it:</para>
</step>
<step><para>Make sure that the following line is uncommented in the control
file <filename>/etc/inetd.conf</filename> <screen>tftp dgram   udp     wait    root    /usr/sbin/tcpd      /usr/sbin/in.tftpd
</screen></para>
<para></para>
</step>
<step><para>If it was necessary to change the line in Step 2, then the inetd
server must be restarted, which can be done via the command:    <programlisting>
# service inet reload</programlisting></para>
</step>
</procedure>
</sect3>
<sect3>
<title>Enable TFTP on Red Hat Linux 7 (or newer)</title>
<procedure>
<step><para><indexterm><primary>TFTP</primary><secondary>enabling on Red Hat
Linux 7</secondary></indexterm><indexterm><primary>Red Hat Linux</primary>
<secondary>enabling TFTP on version 7</secondary></indexterm>Ensure that the
xinetd RPM is installed.</para>
</step>
<step><para>Ensure that the tftp-server RPM is installed.</para>
</step>
<step><para>Enable TFTP by means of the following: <programlisting>/sbin/chkconfig tftp on
</programlisting>Reload the xinetd configuration using the command:<programlisting>
 /sbin/service xinetd reload </programlisting>Create the directory /tftpboot
using the command <programlisting>mkdir /tftpboot</programlisting></para>
</step>
</procedure>
<note><title>NOTE</title>
<para>Under Red Hat 7 you must address files by absolute pathnames, for example: <filename>
/tftpboot/boot.img</filename> not <filename>/boot.img</filename>, as you may have done with
other implementations.
On systems newer than Red Hat 7 (7.1 and beyond), filenames are once again relative to the
<filename>/tftpboot</filename> directory.
</para>
</note>
</sect3>
<sect3>
<title>Enable BOOTP/DHCP server on Red Hat Linux</title>
<para><indexterm><primary>DHCP</primary><secondary>enabling on Red Hat Linux
</secondary></indexterm><indexterm><primary>BOOTP</primary><secondary>
enabling on Red Hat Linux</secondary></indexterm>First, ensure that you have
the proper package, <computeroutput>dhcp</computeroutput> (not <computeroutput>
dhcpd</computeroutput>) installed. The DHCP server provides Dynamic Host Configuration,
that is, IP address and other data to hosts on a network. It does this in
different ways. Next, there can be a fixed relationship between a certain
node and the data, based on that node&rsquo;s unique Ethernet Station Address
(ESA, sometimes called a MAC address). The other possibility is simply to
assign addresses that are free. The sample DHCP configuration file shown does
both. Refer to the DHCP documentation for more details.</para>
<example><title>Sample DHCP configuration file</title>
<programlisting>--------------- /etc/dhcpd.conf -----------------------------
default-lease-time 600;
max-lease-time 7200;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option domain-name-servers 198.41.0.4, 128.9.0.107;
option domain-name &ldquo;bogus.com&rdquo;;
allow bootp;
shared-network BOGUS {
subnet 192.168.1.0 netmask 255.255.255.0 {
         option routers 192.168.1.101;
         range 192.168.1.1 192.168.1.254;
}
 }
host mbx {
         hardware ethernet 08:00:3E:28:79:B8;
         fixed-address 192.168.1.20;
         filename &ldquo;/tftpboot/192.168.1.21/zImage&rdquo;;
         default-lease-time -1;
         server-name &ldquo;srvr.bugus.com&rdquo;;
         server-identifier 192.168.1.101;
         option host-name &ldquo;mbx&rdquo;;
} </programlisting></example>
<para>Once the DHCP package has been installed and the configuration file
set up, type:<screen>
# <userinput>service dhcpd start</userinput></screen></para>
</sect3>
<sect3>
<title>Enable DNS server on Red Hat Linux</title>
<para><indexterm><primary>DNS</primary><secondary>enabling on Red Hat
Linux</secondary></indexterm>First, ensure that you have the proper
RPM package, <computeroutput>caching-nameserver</computeroutput>
installed. Then change the configuration
(in <filename>/etc/named.conf</filename>) so that the
<computeroutput>forwarders</computeroutput> point to the primary
nameservers for your machine, normally using the nameservers listed in
<filename>/etc/resolv.conf</filename>.</para>

<example><title>
Sample <filename>/etc/named.conf</filename> for Red Hat Linux 7.x
</title>

<programlisting>--------------- /etc/named.conf -----------------------------
// generated by named-bootconf.pl

options {
        directory "/var/named";
        /*
         * If there is a firewall between you and nameservers you want
         * to talk to, you might need to uncomment the query-source
         * directive below.  Previous versions of BIND always asked
         * questions using port 53, but BIND 8.1 uses an unprivileged
         * port by default.
         */
        // query-source address * port 53;


        forward first;
        forwarders {
                212.242.40.3;
                212.242.40.51;
        };
};

//
// a caching only nameserver config
//
// Uncomment the following for Red Hat Linux 7.2 or above:
// controls {
//         inet 127.0.0.1 allow { localhost; } keys { rndckey; };
// };
// include "/etc/rndc.key";
zone "." IN {
        type hint;
        file "named.ca";
};

zone "localhost" IN {
        type master;
        file "localhost.zone";
        allow-update { none; };
};

zone "0.0.127.in-addr.arpa" IN {
        type master;
        file "named.local";
        allow-update { none; };
};

</programlisting></example>

<para>Make sure the server is started with the command:
<screen># <userinput>service named start</userinput></screen> and is
started on next reboot with the command
<screen># <userinput>chkconfig named on</userinput></screen>
Finally, you may wish to change
<filename>/etc/resolv.conf</filename> to use
<computeroutput>127.0.0.1</computeroutput> as the nameserver for your
local machine.</para>
</sect3>
<sect3>
<title>RedBoot network gateway</title>
<para><indexterm><primary>RedBoot network gateway</primary></indexterm><indexterm>
<primary>network gateway</primary></indexterm>RedBoot cannot communicate with
machines on different subnets because it does not support routing. It always
assumes that it can get to an address directly, therefore it always tries
to ARP and then send packets directly to that unit. This means that whatever
it talks to must be on the same subnet. If you need to talk to a host on a
different subnet (even if it's on the same &lsquo;wire&rsquo;), you need to
go through an ARP proxy, providing that there is a Linux box connected to
the network which is able to route to the TFTP server. For example: <filename>
/proc/sys/net/ipv4/conf/<replaceable>&lt;interface></replaceable>/proxy_arp </filename>where <replaceable>
&lt;interface></replaceable>should be replaced with whichever network interface
is directly connected to the board.</para>
</sect3></sect2>
<sect2>
<title>Verification</title>
<para><indexterm><primary>verification (network)</primary></indexterm><indexterm>
<primary>network verification</primary></indexterm>Once your network setup
has been configured, perform simple verification tests as follows: <itemizedlist>
<listitem><para>Reboot your system, to enable the setup, and then try to &lsquo;ping&rsquo;
the target board from a host.</para>
</listitem>
<listitem><para>Once communication has been established, try to ping
a host using the RedBoot ping command - both by IP address and hostname.</para>
</listitem>
<listitem><para>Try using the RedBoot load command to download a file
from a host.</para>
</listitem>
</itemizedlist></para>
</sect2></sect1></chapter>

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