Eurotech VIPER Instruction manual

VIPER / VIPER-Lite
AEL Embedded Linux
Development Kit
Quickstart Manual

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart
ISO 9001
FM12961
Disclaimer
The information in this manual has been carefully checked and is believed to be accurate. Eurotech Ltd assumes no
responsibility for any infringements of patents or other rights of third parties, which may result from its use.
Eurotech Ltd assumes no responsibility for any inaccuracies that may be contained in this document. Eurotech Ltd makes
no commitment to update or keep current the information contained in this manual.
Eurotech Ltd reserves the right to make improvements to this document and/or product at any time and without notice.
Warranty
This product is supplied with a 3 year limited warranty. The product warranty covers failure of any Eurotech Ltd
manufactured product caused by manufacturing defects. The warranty on all third party manufactured products utilised by
Eurotech Ltd is limited to 1 year. Eurotech Ltd will make all reasonable effort to repair the product or replace it with an
identical variant. Eurotech Ltd reserves the right to replace the returned product with an alternative variant or an equivalent
fit, form and functional product. Delivery charges will apply to all returned products. Please check www.eurotech-ltd.co.uk for
information about Product Return Forms.
Trademarks
Linux is a registered trademark of Linus Torvalds.
RedBoot, Fedora and Red Hat are registered trademarks of Red Hat Inc. This product contains a copy of the installation
media for the Fedora Core Linux distribution. This media is not a product of Red Hat, Inc. or the Fedora project and is not
endorsed by Red Hat, Inc. or the Fedora project. It is a product of Eurotech Ltd and we have no relationship with Red Hat,
Inc. or the Fedora project. The media is identical in every respect to the standard Fedora Core install media.
ARM and StrongARM are registered trademarks of ARM Ltd.
Intel and XScale are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and
other countries.
CompactFlash is the registered trademark of SanDisk Corp.
All other trademarks and copyrights referred to are the property of their respective owners.
This product includes software developed by the University of California, Berkeley and its contributors.
All other trademarks recognised.
Revision History
Manual PCB Date Comments
Issue A 18th Aug 2006 First release of manual.
Issue B 25th Sep 2006 Update for Development Kit’s Ethernet cable contents and
corresponding changes.
Issue C 16th October 2007 Minor updates, Eurotech Ltd rebranding.
© 2007 Eurotech Ltd.
For contact details, see page 31.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Contents
© 2007 Eurotech Ltd Issue C 3
Contents
Introduction........................................................................................................................................4
Handling your board safely....................................................................................................4
About this manual..............................................................................................................................5
Related documents................................................................................................................5
Conventions...........................................................................................................................6
Getting started ...................................................................................................................................7
What’s in the kit?....................................................................................................................7
What else do I need?.............................................................................................................8
What peripherals are supported?...........................................................................................9
Unpacking and connecting up..........................................................................................................10
Power supply ...................................................................................................................................13
RedBoot...........................................................................................................................................14
What is RedBoot?................................................................................................................14
AEL Embedded Linux......................................................................................................................16
What’s in AEL Embedded Linux?.........................................................................................16
Booting the system ..............................................................................................................16
Logging in............................................................................................................................17
Setting up networking ..........................................................................................................18
The file system.....................................................................................................................19
Linux kernel .........................................................................................................................20
Hardware configuration........................................................................................................21
Software configuration.....................................................................................................................28
Examples for VIPER / VIPER-Lite ...................................................................................................29
Target support software ...................................................................................................................30
Appendix A – Contacting Eurotech Ltd ............................................................................................31
Index................................................................................................................................................32

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Introduction
© 2007 Eurotech Ltd Issue C 4
Introduction
The VIPER / VIPER-Lite is an ultra low power PC/104 form-factor single board
computer based on the Intel 400MHz PXA255 (VIPER) or 200MHz PXA255
(VIPER-Lite) XScale processor. The PXA255 is an implementation of the Intel XScale
micro-architecture combined with a comprehensive set of integrated peripherals
including:
• Flat panel graphics controller.
• Interrupt controller.
• Real time clock (RTC).
• Multiple serial ports.
The VIPER / VIPER-Lite board offers many features that make it ideal for power-
sensitive embedded communications and multimedia applications.
The AEL Embedded Linux Development Kit provides a ready-to-run platform for Linux
application development and deployment. AEL Embedded Linux is based on the
standard v2.6 kernel and has been configured to load and run from embedded Flash
memory.
Handling your board safely
Anti-static handling
The SBC and other circuit boards contain CMOS devices. These could be damaged in
the event of static electricity being discharged through them. Please observe anti-static
precautions at all times when handling circuit boards. This includes storing boards in
appropriate anti-static packaging and wearing a wrist strap when handling them.
Packaging Should a board need to be returned to Eurotech Ltd, please ensure that it is
adequately packed, preferably in the original packing material.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart About this manual
© 2007 Eurotech Ltd Issue C 5
About this manual
This manual gets you started using the VIPER / VIPER-Lite with RedBoot and AEL
Embedded Linux. It lists the items you should find in your kit, and tells you how to
unpack, connect and configure the board.
AEL Embedded Linux for VIPER / VIPER-Lite is based on the standard v2.6 kernel and
includes the essential features for embedded communication and display solutions.
Eurotech Ltd includes dedicated drivers for the on-board hardware and uses the
embedded Flash memory to store applications.
Related documents
Manuals that you may need are provided in the \manuals section on the CD-ROM that
accompanies your Development Kit. These include the VIPER / VIPER-Lite Technical
Manual, the AEL Embedded Linux Technical Manual and the HOWTO documents.
Most of the HOWTO documents relate to common Linux tasks. Others have been
written specifically for features on the VIPER / VIPER-Lite.
Detailed information aboutAEL Embedded Linux is provided in the AEL Embedded
Linux Technical Manual. The AEL Embedded Linux Technical manual includes
information about the following:
• Configuration files and boot scripts.
• Making an application run automatically at boot.
• AEL Embedded Linux contents and configuration.
• Installation.
• Example programs and utilities.
• Secure Shell (SSH).
• Compiling a kernel.
Please note that the AEL Embedded Linux Technical Manual is a generic manual for
AEL Embedded Linux supplied on Eurotech Ltd boards. As such, the AEL Embedded
Linux manual uses conventions and examples that may or may not be specific to your
board. It is advised that the AEL Embedded Linux manual be used in conjunction with
the instructions and information supplied in the Quickstart and Technical manuals for
your board.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart About this manual
© 2007 Eurotech Ltd Issue C 6
Conventions
Symbols The following symbols are used in this guide:
Symbol Explanation
Note - information that requires your attention.
Tip - a handy hint that may provide a useful alternative or save time.
Caution - proceeding with a course of action may damage your
equipment or result in loss of data.
Indicates that a feature is not available on the standard VIPER-Lite
configuration. Eurotech Ltd can provide custom configurations (subject
to a minimum order quantity) for the VIPER-Lite populated with this
feature. Please contact our Sales team (see AppendixA – Contacting
Eurotech Ltd, page 31) to discuss your requirements.
Typographical conventions
This manual contains examples of commands that you can enter. These are shown as
follows:
$make install DESTDIR=/tmp/target-install
The initial symbol ($ in this case) indicates the prompt that the command is for, and
should not be typed.
The prompts used are explained in the following table:
Prompt Explanation
$ Linux (bash shell) as a regular user.
# Linux (bash shell) as root.
RedBoot> RedBoot command line.
Different fonts are used throughout the manual to identify different types of information,
as follows:
Font Explanation
Italics Parts of a command that should be substituted with appropriate
values.
Bold Information that you enter yourself.
Screen text Information that is displayed on screen.
V
L

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Getting started
© 2007 Eurotech Ltd Issue C 7
Getting started
What’s in the kit?
The VIPER / VIPER-Lite Development Kit includes:
• VIPER-M64-F32, VIPERL-M64-F32 or VIPERL-M64-F16.
• Optional GPIO based VIPER-I/O board (technical manual included on CD)*.
• Standard serial port breakout cable (up to five ports).
• RS-232 serial cable (2m).
• RS-232 null modem adapter.
• Flat panel display cable.
• VIPER FPIF-CRT (breakout assembly with standard CRT socket).
• Ethernet breakout assembly with standard RJ45 socket.
• Ethernet crossover cable.
• GPIO cable with un-terminated ends.
• Reset switch.
• +5V @ 4A max (100-240 VAC input) power supply.
• PC/104 mounting pillars (two sets).
• Development Kit support and installation CD.
• Fedora Core 5 installation DVD1.
• AEL Embedded Linux Technical Manual (on CD).
• USB breakout cable.
• Audio breakout cable.
* Development Kit option
1fedora.redhat.com/
VL
VL

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Getting started
© 2007 Eurotech Ltd Issue C 8
What else do I need?
An x86 Linux system compliant with version 1.3 of the Linux Standard Base2is
required for the AEL Embedded Linux host environment. Suitable systems include PCs
with Debian GNU/Linux, RedHat Linux, Fedora Core or SUSE Linux. The Fedora Core
installation DVD is supplied for this purpose.
In addition, the following information and equipment may be useful:
• Networking details for the VIPER. If your network does not have a DHCP server,
ask your network or system administrator for the following:
- IP address and subnet mask (netmask).
- Default gateway IP address (if required).
- Name server (DNS) IP address (optional).
• Networking details for the host machine.
• Standard Ethernet cable to connect VIPER / VIPER-Lite to a switch or hub.
Alternatively, for standalone systems, the board can be connected directly to your
host machine using the crossover cable provided in the Development Kit.
For more information on setting up a network connection, see the section Setting up
networking, page 18.
2www.linuxbase.org

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Getting started
© 2007 Eurotech Ltd Issue C 9
What peripherals are supported?
The following peripherals/features are supported in this release:
• Five UARTs, COM1 through COM5, including the processor’s internal FFUART,
BTUART and STUART. The VIPER-Lite is only fitted with three COM ports.
• On-board Flash array.
• CompactFlash+.
• Ethernet interface.
• A variety of flat panels running with screen resolutions of 320 x 240 or 640 x 480.
• Power management.
• GPIO.
• Real time clock.
• SRAM.
• USB client.
• Audio codec.
• PC/104 bus. Drivers are available for a range of Eurotech Ltd and third party
PC/104 boards.
• USB host controller.
• RS-422 and RS-485 serial port support.
VL
VL
VL
VL

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Unpacking and connecting up
© 2007 Eurotech Ltd Issue C 10
Unpacking and connecting up
This section guides you, step-by-step, through the process of connecting up the
VIPER / VIPER-Lite for the first time and powering up the system. The VIPER /
VIPER-Lite is delivered ready to run. There are no link settings or configuration
switches that need to be adjusted for the board to operate.
A number of the components are static-sensitive, so standard anti-static
precautions must be taken during use. For more information, see Anti-static
handling, page 4.
If you follow the procedure described below, the board powers up automatically and
loads the RedBoot boot loader from the on-board Flash array. At this point you can
interrupt the boot process, if you wish, and access the Redboot command prompt. If
you do not interrupt the normal boot sequence, after a 1 second pause, the system
continues to load and boot AEL Embedded Linux.
To power up the VIPER / VIPER-Lite and boot AEL Embedded Linux, follow these
steps:
1Remove the VIPER / VIPER-Lite board and all other cables from its packaging. If it
shows any signs of damage during transit, please contact Eurotech Ltd before
proceeding.
Power/Reset input
GPIO heade
r
USB heade
r
LCD
A
udio
Ethernet LED
cable
Ethernet data
cable

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Unpacking and connecting up
© 2007 Eurotech Ltd Issue C 11
For all connections, the red wire on the cable is pin 1. Pin 1 on each connector is
marked on the board.
2The VIPER I/O board can be attached above the main VIPER / VIPER-Lite board
once all connections to the main board are complete.
COM1 (with null modem adapter attached)
Ethernet data
cable
Ethernet LED
cable
Ethernet
breakout
VIPER
FPIF-CRT
A
udio input/output
A
C power suppl
y
Reset switch

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Unpacking and connecting up
© 2007 Eurotech Ltd Issue C 12
3Fit the VIPER / VIPER-Lite power supply cable to the plug on the board.
4Connect a serial terminal emulator3to COM1 using the supplied null modem
adaptor and cable.
5Configure the serial terminal as follows:
• 115200 baud.
• No parity.
• 8 data bits.
• No handshaking.
6Switch on the VIPER / VIPER-Lite board once the terminal emulator is set up on
the host PC.
The Linux operating system is loaded from the on-board Flash memory, and the
board displays a Linux prompt. For a description of AEL Embedded Linux see page
16 of the Technical Manual, which is in the /manuals/ folder on the Development Kit
CD.
3Such as ‘minicom’ running on a Linux PC or ‘Hyper Terminal’ on a Windows PC.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart Power supply
© 2007 Eurotech Ltd Issue C 13
Power supply
The AC Power Supply Unit (PSU) supplied in the kit is rated at 4A @ +5V DC. This is
designed to support the requirements of the VIPER / VIPER-Lite and VIPER-I/O. If
additional devices are powered from this supply, ensure that the overall current rating
is not exceeded.
The following picture shows the PSU connector:
The power connector is polarised to prevent incorrect attachment to the VIPER /
VIPER-Lite board.
Power lead
Reset Switch

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart RedBoot
© 2007 Eurotech Ltd Issue C 14
RedBoot
What is RedBoot?
RedBoot is a complete bootstrap environment for embedded systems. Based on the
eCos Hardware Abstraction Layer, RedBoot inherits the eCos qualities of reliability,
compactness, configurability, and portability.
RedBoot enables download and execution of embedded applications via serial or
Ethernet, including embedded Linux and eCos applications. It can be used for both
product development (debug support) and in deployed products in the field (Flash
update and network booting).
Ethernet download and debug support is included. This means RedBoot can retrieve
its IP parameters via BOOTP or DHCP, and program images can be downloaded using
TFTP or HTTP. Images can also be downloaded over serial (using X- or Y-modem) or
loaded from a JFFS2 file system on the on-board Flash array.
An interactive command-line interface is accessible via serial or Ethernet and allows
management of Flash images, image download, RedBoot configuration, etc. For
unattended or automated startup, boot scripts can be stored in Flash memory. This
allows, for example, loading of images from Flash or a TFTP server.
You cannot use the command-line interface via Ethernet if you have an
automatic boot script enabled to launch an application or another operating
system. RedBoot does not stop to listen for TCP/IP activity.
The AEL Embedded Linux Technical Manual contains details of many of the RedBoot
commands that are useful when using RedBoot as a boot loader for an operating
system (such as Linux) or to launch an application. Full RedBoot documentation is
available in the eCos Reference Manual, which is in the /manuals/ folder on the
Development Kit CD.
Default boot script
The default boot script on the VIPER / VIPER-Lite is configured to load a Linux kernel
from the JFFS2 file system and execute it.
The default boot script for VIPER-Lite is as follows:
clock –l 27 –m 2 –n 10
mount −t jffs2 −f filesystem
load −r −b %{FREEMEMLO} %{kernel}
exec −c %{cmdline}
The default boot script for VIPER is as follows:
clock –l 27 –m 4 –n 10
mount −t jffs2 −f filesystem
load −r −b %{FREEMEMLO} %{kernel}
exec −c %{cmdline}

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart RedBoot
© 2007 Eurotech Ltd Issue C 15
The only difference is that the default boot script initialises the clock to 400MHz for
VIPER and to 200MHz for VIPER-Lite. Refer to following section for more details on
‘clock’ command.
%{FREEMEMLO} is a predefined alias for the lowest address of available memory.
%{kernel} is an alias for the full path name of the Linux kernel to boot. For example:
Redboot> alias kernel “-f /boot/bzImage”
%{cmdline} is an alias for the kernel command line to use. For example:
Redboot> alias cmdline “\”root=/dev/mtdblock2 rootfstype=jffs2 ro
console=ttyS0,115200\””
Refer to the AEL Embedded Linux Technical Manual for further details.
CPU core clock frequency and the clock command
Redboot (V3I7) does not change the clock rate - it remains at the default 100MHz
setting. However, the clock command can be used to set the clock to any of the
frequencies described in the section CPU clock frequency scaling on page 22. This
takes parameters l, m and n correspondingly for the L, M and N settings, which control
the clock speed as described.
While specifying on Redboot command-line, the value of n should be 10 times the
desired value of N, i.e. to set N to 1.5 use the option -n 15. For example:
• To set the clock frequency to 300MHz power saving mode:
RedBoot> clock –l 27 –m 1 –n 30
• To set the clock frequency to 200MHz performance mode:
RedBoot> clock –l 27 –m 2 –n 10
Attempting to run a VIPER-Lite board above 200MHz or a VIPER board
above 400MHz may damage your board permanently.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart AEL Embedded Linux
© 2007 Eurotech Ltd Issue C 16
AEL Embedded Linux
What’s in AELEmbedded Linux?
AEL Embedded Linux is a space-optimised Linux distribution based on Linux kernel
version 2.6. AEL Embedded Linux includes many of the standard file, shell and text
utilities. As well as the basic Linux system, the default installation includes:
• OpenSSH Secure Shell.
• Minimal X Window System.
• Web server.
For a complete list of software and an explanation of how to add and remove packages
please consult the AEL Embedded Linux Technical Manual.
Booting the system
Once the system has been connected and powered up (as described in Unpacking and
connecting up, page 10) the board automatically boots to a Linux prompt, as shown
below.
The example below is typical for a VIPER-M64-F32 board:
Uncompressing Linux................. done, booting the kernel.
...
CPU: XScale−PXA255 [69052d06] revision 6 (ARMv5TE)
...
Machine: Arcom VIPER SBC
Memory policy: ECC disabled, Data cache writeback
Memory clock: 99.53MHz (*27)
Run Mode clock: 398.13MHz (*4)
Turbo Mode clock: 398.13MHz (*1.0, active)
For VIPER-Lite, the clock shows 199.07MHz instead of 398.13MHz (as
shown above).
...
Kernel command line: root=/dev/mtdblock2 rootfstype=jffs2 ro
console=ttyS0,115200
...
3 RedBoot partitions found on MTD device flash
Creating 3 MTD partitions on "flash":
0x00000000−0x0001f000 : "FIS directory"
0x0001f000−0x00020000 : "RedBoot config"
0x00020000−0x02000000 : "filesystem"
This partition table is for a VIPER-M64-F32 board (with 32MB of Flash
memory). The layout is different for boards with 16MB Flash memory.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart AEL Embedded Linux
© 2007 Eurotech Ltd Issue C 17
...
INIT: version 2.85 booting
...
Configuring network interfaces...
If you do not have a DHCP server and you have not configured a static IP
address the board pauses at this point while it searches for a DHCP server.
See Setting up networking, page 18.
... done.
...
INIT: Entering runlevel: 3
Starting system log daemon: syslogd.
Starting kernel log daemon: klogd.
Starting NFS common utilities: statd.
Loading /etc/console/keymap.gz
Starting internet superserver: inetd.
Starting http server: thttpd.
Starting OpenBSD Secure Shell Server: sshd.
Starting periodic command scheduler: cron.
Arcom Embedded Linux (ttyS0)
viper login:
Logging in
You can login to the VIPER / VIPER-Lite as root (the superuser or administrator) using
the following details:
Login name: root
Default password: arcom
Alternatively you can log into a user account called arcom using the following details:
Login name: arcom
Default password: arcom

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart AEL Embedded Linux
© 2007 Eurotech Ltd Issue C 18
Setting up networking
As supplied, the board uses the DHCP protocol to configure the network. This requires
a DHCP server to be available on your network. For more information, please consult
your network administrator.
To configure the VIPER / VIPER-Lite to use a static IP address, follow these steps:
1 Log in to the VIPER / VIPER-Lite by entering the following log in details:
Login name: root
Password: arcom
2 Edit the file /etc/network/interfaces using the nano editor.
# nano /etc/network/interfaces
The vi editor is also installed, in case you prefer to use this.
3Modify the iface eth0 inet dhcp line to look like the following (substituting your own
IP address and netmask):
iface eth0 inet static
address 10.7.28.2
netmask 255.255.0.0
gateway 10.7.1.1
4Save the file by holding down Ctrl and pressing O.
5Exit by holding down Ctrl and pressing X.
6Optional. Set up a Domain Name System (DNS) server if required. You need a
DNS server if you want to use domain names (such as www.eurotech-ltd.co.uk)
when accessing the Internet.
To set up a DNS server, edit the file /etc/resolv.conf and add your DNS server
address as follows:
nameserver 10.7.1.9
7Reinitialise the networking by typing:
# /etc/init.d/networking restart
The following is displayed:
Reconfiguring network interfaces...done
For standalone systems where the VIPER / VIPER-Lite is connected directly to the
host system through an Ethernet crossover cable, you can modify the settings of the
VIPER / VIPER-Lite and the host system, similar to the example shown above, to set
up a network between them.
Chapters 25 and 26 of the RUTE Manual provide a useful introduction to TCP/IP
networking. This manual is on the Development Kit CD, in the /manuals/ folder.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart AEL Embedded Linux
© 2007 Eurotech Ltd Issue C 19
The file system
The file system used on the VIPER / VIPER-Lite Flash memory is a compressed
Journaling Flash File System (JFFS2). JFFS2 has the following advantages:
• Robustness.
• Power fail safe.
• No integrity scan (fsck) is required at boot time.
• Flash wear levelling.
• Transparent compression, with a typical compression ratio of 2:1.
The on-board Flash is partitioned using RedBoot FIS, as shown in the following table:
Partition # Block device Size (KB) Offset (KB) Description
0 /dev/mtdblock0 124 0 Partition table
1 /dev/mtdblock1 4 124 RedBoot configuration
2 /dev/mtdblock2 remainder 128 Root file system
Previous versions of AEL Embedded Linux on the VIPER / VIPER-Lite made
use of a separate kernel partition. From version 4 issue 1 onwards, the
kernel is stored as a regular file in the /boot/ folder on the root file system.
In addition, a 4MB RAM-based file system is mounted on /var/tmp for temporary files.
These are lost on reboot.
The basic AEL Embedded Linux install uses about 13.9MB of physical Flash. On a
board with 32MB of Flash memory fitted, this leaves about 18.1MB free. This is about
36MB of free space, assuming a typical 2:1 compression ratio. For a board fitted with
16MB of Flash memory, there is approximately 2MB of free space. This is about 4MB
of free space, assuming the same compression ratio.
You can make additional space available by removing unused packages. For example,
if you do not require video support, removing xorg and it’s components could release
about 2MB. For more information on removing packages, refer to theAEL Embedded
Linux Technical Manual, which is in the /manuals/ folder on the Development Kit CD.
The default Flash image is on the Development Kit CD, in the /images/ folder. For an
explanation of how to reload a complete Flash image, see the AEL Embedded Linux
Technical Manual.

VIPER / VIPER-Lite AEL Embedded Linux Dev. Kit Quickstart AEL Embedded Linux
© 2007 Eurotech Ltd Issue C 20
Linux kernel
The version of the Linux kernel used on the VIPER / VIPER-Lite is a standard Linux
2.6 kernel tree with patches to provide support for Eurotech Ltd’s boards.
Source and configuration
The kernel sources are installed in the host environment as /opt/arcom/src/linux-
source-VERSION.tar.gz.
Once you have unpacked the kernel source you can configure the default VIPER /
VIPER-Lite kernel with:
$ make ARCH=arm viper_defconfig
The kernel may now be built and installed as described in theAEL Embedded Linux
Technical Manual.
Default command line
The default kernel command line is:
root=/dev/mtdblock2 rootfstype=jffs2 ro console=ttyS0,115200