U-boot bootloader

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LinkStation port version 2.0
2 September 2006

Copyright (c) 2006 Mihai Georgian
E-mail your questions and comments at u-boot (at) linuxnotincluded (dot) org (dot) uk.


There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. The LinkStation port of U-Boot described here supports only the PowerPC based Linkstation and KuroBox. This version of U-Boot will certainly BRICK the MIPSel LinkStation LS2 (model HD-HLAN-2)



Das U-Boot

U-Boot is a universal boot loader released with full source code under the Gnu Public License (GPL). For an overview of U-Boot, you can read Introduction to Das U-Boot, the universal open source bootloader .


Supported Hardware

The LinkStation port of U-Boot described here supports the following PowerPC models:

  1. LinkStation version 1 (model HD-HLAN-1)
  2. KuroBox standard
  3. LinkStation HG (model HD-HGLAN)
  4. KuroBox HG

There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. This version of U-Boot will certainly not work on the the LinkStation version 2 (model HD-HLAN-2) as the LinkStation version 2 is based on a MIPS processor. The MIPS processor is completely different from the PowerPC processor and attempting to flash a LinkStation version 2 with PowerPC firmware it is guaranteed to make it completely unusable.

To find out more about the different LinkStation and KuroBox models, visit: Buffalo/Melco Network Attached Storage Variants.


  • supports serial console and net console (nc)
  • supports erasing and programming of the on-board flash ROM
  • supports file downloading
    • over the serial line
    • over the network (tftp, bootp, dhcp, nfs)
    • from the hard drive (supports both normal ext2 and LinkStation modified "ext2" file systems)
  • boots Linux (supports both U-Boot images and LinkStation "flashimg" images, including the original kernel from flash)
  • boots in EM mode
  • uses the LinkStation buttons as a minimal console
    • the power button (the big button at the front) to stop / start the boot process and to select the image to boot
    • the reset button to switch between consoles

Supported Commands

?       - alias for 'help'
base    - print or set address offset
bdinfo  - print Board Info structure
boot    - boot default, i.e., run 'bootcmd'
bootd   - boot default, i.e., run 'bootcmd'
bootm   - boot application image from memory
bootp   - boot image via network using BootP/TFTP protocol
cmp     - memory compare
coninfo - print console devices and information
cp      - memory copy
crc32   - checksum calculation
dhcp    - invoke DHCP client to obtain IP/boot params
diskboot- boot from IDE device
echo    - echo args to console
erase   - erase FLASH memory
ext2load- load binary file from a Ext2 filesystem
ext2ls  - list files in a directory (default /)
flinfo  - print FLASH memory information
go      - start application at address 'addr'
help    - print online help
ide     - IDE sub-system
loadb   - load binary file over serial line (kermit mode)
loads   - load S-Record file over serial line
loop    - infinite loop on address range
md      - memory display
mm      - memory modify (auto-incrementing)
mtest   - simple RAM test
mw      - memory write (fill)
nfs     - boot image via network using NFS protocol
nm      - memory modify (constant address)
pci     - list and access PCI Configuration Space
ping    - send ICMP ECHO_REQUEST to network host
printenv- print environment variables
protect - enable or disable FLASH write protection
rarpboot- boot image via network using RARP/TFTP protocol
reset   - Perform RESET of the CPU
run     - run commands in an environment variable
saveenv - save environment variables to persistent storage
setenv  - set environment variables
tftpboot- boot image via network using TFTP protocol
version - print monitor version

A useful document on u-boot is the u-Boot Refence Guide produced by FreeScale. This guide is targetted at a different processor to the one used in Buffalo products, but many of the commands are common and this document gives detailed examples of the syntax of those commands

RAM Build and Uloader

Normally, U-Boot resides in the on-board flash and starts executing at reset. It initialises the CPU, the memory controller and the serial port and then relocates itself at the upper end of the RAM area. After relocation, U-Boot completes the hardware initialisation and then it either proceeds to boot the OS kernel or displays a command prompt and waits for operator input.

U-Boot for the LinkStation can be configured for a RAM build. The only differences between the ROM and RAM builds are the absence of the basic initialisation code (which can only run from ROM) and the link address. You can test your RAM build using uloader.o which is a kernel module that was written specifically for the purpose of loading and starting a RAM build of U-Boot.

Even for the same model, there are hardware differences between the individual LinkStations and, due to these differences, U-Boot might not work properly in some instances. For example, your flash chip might not be supported by the current version of the U-Boot port. It is strongly recommend you test thoroughly U-Boot on your LinkStation using a RAM build before building the ROM version and attempting to burn it into flash. Once you have the RAM build up and running you can use it to install (burn) the ROM version.

Source Code

U-Boot for the LinkStation is distributed as a patch for U-Boot version 1.1.4. You can compile it using either a cross toolchain or, if you have a development environment installed, natively on your LinkStation. I used the DENX Embedded Linux Development Kit (ELDK) version 3.1.1 which comes with gcc 3.3.3 (gcc version 3.3.3 20040412 (Red Hat Linux 3.3.3-7)) with specific patches for PowerPC.

Uloader is distributed as a gzip-ed tar archive which contains the full source code, the binary module, uloader.o, compiled for the original LinkStation kernel and a simple bash script which uses uloader to load a RAM build of U-Boot and start it. Two tar archives are provided. The source code is the same in both archives. The binary module in the first archive has been compiled for the original LinkStation kernel 2.4.17_mvl21-sandpoint. The binary module in the second archive has been compiled for the original LinkStation HG kernel 2.4.20_mvl31-ppc_linkstation.

Installing U-Boot for LinkStation

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If you are using a pre-compiled version of U-Boot make sure that it is one intended for your machine. As an example the version of U-Boot used on the Power PC (PPC) based machines (LS1, LS-HG, LS-HS) is different from that used on the LinkStation version 2 (HD-HLAN-2). The LS2 uses a MIPS processor which is completely different from the PowerPC processor used in the LinkStation version 1.


There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. When installing firmware on an embedded computer things can go wrong. The power can go down in the middle of the flash or the flash operation can fail rendering your LinkStation unusable. If you are not prepared to lose your LinkStation, do not attempt to install U-Boot.


U-Boot for the LinkStation is distributed as a source patch against u-boot-1.1.4. To compile it you will need either a cross toolchain installed on your PC or native development tools installed on your LinkStation. These instructions assume that you are running Linux on a X86 PC and that you are using a cross toolchain.

To allow testing of U-Boot on your LinkStation without burning it into flash, a kernel module named uloader.o is provided. Uloader allows you to use Linux to load a RAM build of U-Boot and start it. The RAM build of U-Boot is very close to the ROM build. The only differences are the absence of the basic initialisation code (which cannot run from RAM) and the link address. It is strongly recommended that you test U-Boot on your LinkStation using a RAM build before building the ROM version and attempting to burn it into flash. Once you have the RAM build up and running you can use it to install (burn) the ROM version.

Get telnet Access

Try to connect to your LinkStation using telnet. If you see the telnet command prompt, read CGI Exploit (PowerPC) original method of Hacking the LinkStation about how to get telnet access.

If the above method doesn't work for you, read Turn your LinkStation into a Kuro Box (PowerPC) for other methods to get telnet access.

The above methods do not work for the LinkStation HG. For this model, the only solution is to load a telnet-enabled version of the firmware. Read the pages about OpenLink and the firmware flasher

You can also try to flash a modified version of the original firmware.

Install the Serial Console

Read Add a Serial port to the PowerPC Linkstation to learn how to install the serial console.

Nuvola apps important.png 

Installing the serial console is not an absolute requirement and it will void your warranty. U-Boot can be installed and controlled without it. However, the serial console will give you the best control over both U-Boot and Linux.

Install nc

If you haven't installed the serial console you will need to install nc (net console) on your workstation (not on the LinkStation). Nc comes standard with most Linux distributions. For more information, visit the netcat home page http://netcat.sourceforge.net or http://www.vulnwatch.org/netcat for the Windows version.

Get the ELDK

If you don't have a cross toolchain installed, download the DENX Embedded Linux Development Kit (ELDK) from http://ftp.sunet.se/pub/Linux/distributions/eldk/3.1.1/ppc-linux-x86/iso/ppc-2005-03-07.iso, install it and spend some time getting familiar with it.

It's a good idea to verify it's md5sum: http://ftp.sunet.se/pub/Linux/distributions/eldk/3.1.1/ppc-linux-x86/iso/MD5SUM [code]9a5e5869d8061f962274d41713b0610e ppc-2005-03-07.iso[/code]

ELDK Installation

Mount the ELDK ISO

Install at say /home/ELDK directory. And install the necssary tool chain for the PPC:

# ./install -d /home/ELDK ppc_6xx

In preparation for building, export directories /home/ELDK/usr/bin, /home/ELDK/bin and /home/ELDK/ppc-linux/usr/bin as follows:

# export PATH=/home/ELDK/usr/bin:/home/ELDK/bin:/home/ELDK/usr/ppc-linux/bin:$PATH


Create the build directory and set the environment variable UBOOT_BUILD to the path to it

# mkdir <your_build_directory>
# export UBOOT_BUILD=<your_build_directory>

Download the tarball for u-boot-1.1.4 from ftp://ftp.denx.de/pub/u-boot/u-boot-1.1.4.tar.bz2
Download the LinkStation patch, u-boot-1.1.4-list-2.01.diff.gz
Download the uloader module for your LinkStation / KuroBox model.

Both tar files contain the same sources but the binary has been compiled against the corresponding version of the kernel.

Untar u-boot-1.1.4 and apply the patch.

# tar xjf u-boot-1.1.4.tar.bz2
# cd u-boot-1.1.4
# gunzip -c ../u-boot-1.1.4-list-2.01.diff.gz | patch -p1 -u

Note: To use the vanilla 2.6 standard kernels (lyakh's mainline kernels) for the Linkstation 1, Linkstation HG, Kurobox Standard, Kurobox HG, one must a forward patched version of LNI's u-boot (ver 1.2.0) which contains dtc support. Please follow the directions found here: http://www.nas-central.org/index.php/Kurobox_support_in_stock_2.6_kernels

Untar the uloader archive. The archive contains the source code, a binary module compiled for the original LinkStation kernel and a simple bash script to load and start a RAM build of U-Boot. The binary in uloader-2.4.17.tar.gz has been compiled against 2.4.17_mvl21-sandpoint and the binary in uloader-2.4.20.tar.gz has been compiled against 2.4.20_mvl31-ppc_linkstation. If you have a different kernel version, you may need to recompile the module for your kernel. Compiling the module requires a fully configured LinkStation kernel tree and gcc 2.95 (cross compiler).

LinkStation 1 / KuroBox standard

# cd ..
# tar xzf uloader-2.4.17.tar.gz
# cd u-boot-1.1.4

LinkStation HG / KuroBox HG

# cd ..
# tar xzf uloader-2.4.20.tar.gz
# cd u-boot-1.1.4

Source your ELDK environment

# . <path_to_your_ELDK>/config_6xx


Edit include/configs/linkstation.h and set the following variables for your environment:

CONFIG_IPADDR_LS - the IP address of your LinkStation while running U-Boot (mandatory)
CONFIG_SERVERIP_LS - the IP address of the NFS/TFTP/DHCP/BOOTP server, normally the address of your workstation (mandatory)
CONFIG_NCIP_LS - the address of the computer running net console, normally the address of your workstation (optional. If the define is missing, CONFIG_NCIP_LS will be set to the same value as CONFIG_SERVERIP_LS

RAM Build

When using make be sure the version of make is 3.80

For LinkStation 1 / KuroBox standard run:

make linkstation_HDLAN_RAM_config
make linkstation_HDLAN_RAM

The name of the resulting binary is u-boot-hd.ram.bin

For LinkStation HG / KuroBox HG run:

make linkstation_HGLAN_RAM_config
make linkstation_HGLAN_RAM

The name of the resulting binary is u-boot-hg.ram.bin

Minimal Console

This port of U-Boot to the LinkStation is designed to allow some control over the boot process even in the absence of a console. For this, it uses the power button (the big button at the front) and the reset button (the small red button at the back).

When the LinkStation is switched on, the power LED starts blinking and, very quickly, it starts booting the kernel from flash. If U-Boot is installed, the power LED will change from blinking quickly to blinking very slowly. This means that U-Boot has taken over and it is counting down the boot delay before booting the kernel. The default boot delay is 10 sec. From the moment when the power LED starts blinking slowly and for the duration of the boot delay, you can control the boot process with the power and reset buttons.

The Power Button

If you push the power button and keep it pressed for more than 1 sec, the boot process will stop and the LinkStation will wait for a command. A stopped boot process is indicated by the power LED being lit solid. The effect is the same a pressing 's' on the console.

A long push of the power button acts as a toggle. If the boot delay count down is in progress, a long push of the power button stops the boot process. If the boot process is stopped (U-Boot is at the command prompt, even if you can't see it), a long push of the power button restarts the boot process resetting the boot delay to its original value.

By default U-Boot supports three pre-configured boot commands:

  1. The first boot command will attempt to load and boot a file named boot/vmlinux.UBoot from the first hard disk partition, /dev/hda1. The file can be in any of the U-Boot bootable formats but uImage is the preferred format. If the file is missing or corrupted, U-Boot will fall back to booting the original kernel from flash.
  2. The second boot command will boot the original kernel from flash.
    Please note that the original kernel for the LinkStation 1 / KuroBox standard has a bug in the function that calibrates the decrementer and it will stop for up to 180 sec during boot. This bug is not an U-Boot bug but a kernel bug which is uncovered by the fact that U-Boot activates the decrementer where the original boot loader does not.
    The original kernel for LinkStation HG / KuroBox HG does not suffer from the above problem.
  3. The third boot command will attempt to boot in emergency mode (EM). It does this by passing the argument root=/dev/ram0 to the kernel.

LinkStation / LinkStation HG owners should avoid booting in EM mode as the root password for this mode on the LinkStation is unknown. The original kernel for the LinkStation / KuroBox standard and for some of the earlier LinkStation HG / KuroBox HG models ignores the root argument. These models will boot normally from the on-board flash when the EM boot command is used. Read the section on EM mode if your LinkStation HG / KuroBox HG has a kernel that doesn't boot in EM mode using this boot command.

You can cycle through the boot commands with the power button.

To see which of the three commands U-Boot is going to execute, press the power button quickly. The HDD LED (the third from the top) will start blinking. The number of times the LED blinks, shows the number of the active boot command. For example, a pattern short on - short off - short on - long off, means that the boot command number 2 is active. U-Boot will repeat the blinking cycle for a total duration of about 5 sec counting from the moment the power button is released.

A short press of the power button while the HDD LED is blinking will advance the boot command to the next one.

The Reset Button

Two consoles are currently configured, the serial console and the net console. The first console is the net console (nc) and the second console is the serial console.

The reset button can be used, similarly to the power button, to switch consoles. A press on the reset button (here, it doesn't matter how long you keep the button pressed) displays the currently active console using the HDD LED. Repeatedly pressing the reset button while the HDD LED is blinking will toggle between the two consoles. The blinking pattern is different from the one showing the boot command. The pattern which shows that the second (serial) console is active is short off - short on - short off - long on. U-Boot will repeat the blinking cycle for a total duration of about 5 sec counting from the moment the reset button is released.

Load and Test

Mount the LinkStation SMB public share and copy the following files to it:

For LinkStation 1 / KuroBox standard

# mount -t smbfs -o password="" //<your_linkstation_name_or_ip>/share/mnt
# cp u-boot-hd.ram.bin /mnt
# cp ../uloader-2.4.17/uloader.o /mnt
# cp ../uloader-2.4.17/u-boot-load.sh /mnt
# umount /mmt

For LinkStation HG / KuroBox HG

# mount -t smbfs -o password="" //<your_linkstation_name_or_ip>/share/mnt
# cp u-boot-hg.ram.bin /mnt
# cp ../uloader-2.4.20/uloader.o /mnt
# cp ../uloader-2.4.20/u-boot-load.sh /mnt
# umount /mmt

Most people don't have the serial port installed and this is why the net console is the default console. If you installed the serial port, open another window and use minicom to connect to your LinkStation serial console. The serial port settings are 57600,N,8, the same as the settings used by the original Linux kernel.

The net console is the default console so you need to have nc installed. Open another window and run board/linkstation/nc.sh. To quit nc, press ^T (control-T).

# cd $UBOOT_BUILD/u-boot-1.1.4
# board/linkstation/nc.sh <ip_of_your_linkstation>

Where <ip_of_your_linkstation> is CONFIG_IPADDR_LS (see Configure U-Boot above). When you run nc.sh nothing will be written to the screen. This is normal as Linux is not using the net console.

From your original window, use telnet to connect to the LinkStation and launch U-Boot. Replace lshg in the example below with the name / IP address of your LinkStation. Replace myroot with the login you created when you gained telnet access. Type the commands shown in bold below.

# telnet lshg
Connected to lshg.
Escape character is '^]'.


HD-HGLAN6C5 login: myroot
Linux (none) 2.4.20_mvl31-ppc_linkstation #3 Thu May 19 13:34:18 JST 2005 ppc unknown
root@HD-HGLAN6C5:~# cd /mnt/share
root@HD-HGLAN6C5:/mnt/share# ./u-boot-load-hg.sh
root@HD-HGLAN6C5:/mnt/share# exit
Connection closed by foreign host.

If you have a serial console you should see the initial U-Boot startup messages. Even if the default console is the net console, U-Boot sends startup messages to the serial port until it initialises the network controller.

U-Boot 1.1.4 LiSt 2.0 (Sep 2 2006 - 16:49:46) LinkStation HG / KuroBox HG

CPU: MPC8245 Revision 1.4 at 262.144 MHz: 16 kB I-Cache 16 kB D-Cache
DRAM: 128 MB
*** Warning - bad CRC, using default environment

00 0b 10ec 8169 0200 ff
00 0c 1283 8212 0180 ff
00 0e 1033 0035 0c03 ff
00 0e 1033 0035 0c03 ff
00 0e 1033 00e0 0c03 ff

Watch the net console window. After a few seconds, time needed by U-Boot to initialise the network controller and the IDE controller you should see the U-Boot messages.

IDE: Bus 0: OK
Device 0: Model: Maxtor 7Y250P0 Firm: YAR41BW0 Ser#: Y62W8PDE
Type: Hard Disk
Supports 48-bit addressing
Capacity: 239372.4 MB = 233.7 GB (490234752 x 512)
Boot in 10 seconds ('s' to stop)...

Press 's' on your keyboard to stop the boot process.

If you want to use only the serial console, watch the power LED of your LinkStation. When it starts blinking very slowly, use the power button to stop the boot process. Wait for the power LED to go dim and press and hold the power button until the LED lights up brightly indicating that the boot process has stopped. Now press the reset button twice and you should see the U-Boot command prompt (=>) in your minicom window. You can now control U-Boot from the minicom window.

When using nc on the LinkStation 1 / KuroBox standard, you will notice that the console is quite unresponsive and loses characters quite often. This is due to the way U-Boot implements the net console. U-Boot calls the net console driver in the main command loop. The driver starts the network controller, and waits for a net console packet. If no packet is received within 1 msec, the driver shuts down the network controller. I have increased the the net console driver timeout from the original 1 msec to 50 msec and, as a result, the net console has become somewhat usable. If a character is not echoed back to you, it was lost. Keep typing it until you see it echoed to the screen. After a while you will get a feel of the best typing speed to minimise the character loss.

Once you get the U-Boot command prompt, start testing it. Read the documentation and try each command you are interested in. A very important command is flinfo which displays information about the flash chip. If the information displayed is correct for your flash, check the flash erase and flash write commands. To do this, you will need to find an empty sector, one for which each byte is 0xFF. Hint: check the last flash sector first, chances are that it's empty. When you are testing commands that write to the flash, always remember that you can write a single byte but you can only erase whole sectors.

Nuvola apps important.png 

Test the flash commands thoroughly before deciding to burn U-Boot into flash. Write at least 128 kB to the flash to test potential timeout problems.
The flash routines in this version of U-Boot for the LinkStation should be able to identify and handle any CFI flash which uses the AMD standard command set. However, they were tested only on a LinkStation with a Fujitsu MBM29PL32TM flash chip and on a LinkStation HG with a ST Micro M29DW324DB flash chip.

ROM Build

Once you are happy with the RAM build, you are ready for the ROM build.

For LinkStation 1 / KuroBox standard run:

make linkstation_HDLAN_config
make linkstation_HDLAN

The name of the resulting binary is u-boot-hd.flash.bin

For LinkStation HG / KuroBox HG run:

make linkstation_HGLAN_config
make linkstation_HGLAN

The name of the resulting binary is u-boot-hg.flash.bin



There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. Be very careful not to flash your hardware with the wrong U-Boot build. Flashing any RAM build or flashing a ROM build for the LinkStation 1 / KuroBox standard into the LinkStation HG / KuroBox HG or viceversa will "brick" your device.

This is especially true if you are flashing from Linux as U-Boot has safety checks to avoid flashing the wrong build.

Flashing U-Boot from U-Boot

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If your power LED is blinking, do NOT flash from u-boot. Your LS is likely going to reboot itself. If this happens before the flash has completed, you will create a brick.

The RAM build of U-Boot can be used to load and flash the ROM build. This is the preferred method.

Boot your LinkStation normally. Open a telnet session and create a directory to hold the U-Boot flash image.

root@linkstation:~# cd /mnt/share
root@linkstation:/mnt/share# mkdir u-boot

Copy the U-Boot flash image to your LinkStation SMB share in the directory u-boot.

Load the RAM build of U-Boot and at the U-Boot command prompt type:

=> run upgrade

U-Boot will attempt to load the ROM build from the directory share/u-boot/ on the third partition of the hard drive. If the load is successful, it will do the following:

  1. unprotect the bootloader area;
  2. erase the bootloader area;
  3. copy the loaded file to the bootloader area;
  4. verify the copy;

Here is the output of run upgrade

=> run upgrade
Loading 0:3:share/u-boot/u-boot-hg.flash.bin

174668 bytes read
Un-Protected 3 sectors

Flash erase: first = 55 @ 0xfff00000
last = 57 @ 0xfff20000
Flash erase: Done
Erased 3 sectors
Copy to Flash... done
Total of 174668 bytes were the same

When the above sequence finishes, U-Boot returns to the command prompt (=>). Depending on your flash chip, the flash operation can take a long time. Wait patiently and do not try to power down or otherwise interrupt the flash or you will end up with a "brick".


=> reset

The power LED should start blinking slowly and, if you have a serial console, you should see the U-Boot startup messages. Your LinkStation is now running U-Boot.

Flashing U-Boot from Linux

Connect to your LinkStation using either the serial port or telnet.

For LinkStation 1 / KuroBox standard run:

# cd /mnt/share/u-boot
# dd if=u-boot-hd.flash.bin of=/dev/fl2 bs=1k
# cmp u-boot-hd.flash.bin /dev/fl2

For LinkStation HG / KuroBox HG run:

# cd /mnt/share/u-boot
# dd if=u-boot-hg.flash.bin of=/dev/mtd1 bs=1k
# cmp u-boot-hg.flash.bin /dev/mtd1

The above commands for LinkStation HG / KuroBox HG will work on devices with the original kernel version 2.4.20 and may work on earlier devices using kernel version 2.4.17. Please check which device corresponds to the bootloader partition on your hardware.

If the Flash Fails

If the flash was not written correctly but U-Boot returns at the command prompt, try to re-run run upgrade.

If the same happens when you attempt to install U-Boot from Linux, try to dd again.

If your flash fails completely, for example due to a power failure, all is not completely lost. You can still use a JTAG cable to re-flash your Linkstation. Unfortunately, this is a relatively complicated and expensive solution as it involves acquiring or building the JTAG cable and soldering the header for it on the LinkStation motherboard. For more information on how to use a JTAG cable with the LinkStation you can visit: Add a Jtag Port.

EM Mode

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for the LinkStation / LinkStation HG users
Do not attempt to boot into EM mode using the method described here. The password for the EM mode is unknown for all LinkStation models.

Once you have U-Boot installed in the on-board flash, you can boot in EM mode even if the third boot command described above doesn't work.

Stop the boot countdown by pressing 's' in your net console window and, at the U-Boot command prompt, run:

=> run writeng
=> run flboot

The above commands write "NGNG" to 0xFFF70000 and boot from the on-board flash. To revert to normal boot by writing "OKOK" to 0xFFF70000, run:

=> run writeok
=> boot

Advanced configuration

The initial U-Boot configuration can be changed by editing the file include/configs/linkstation.h.

In all the examples below, please note the backslash-zero (\0) at the end of the strings and the space-backslash ( \) at the end of each lines and do not change them.

Change the name of the default boot file

Search for the lines containing:

"hdpart=0:1\0" \
"hdfile=boot/vmlinux.UBoot\0" \

and change them to the values you want. Partition 0:1 means disk 0, partition 1. Obviously, you can only change the partition number. The name of the file must be given relative to the root of the partition.

Change the default console to the serial console

Search for the lines containing:

"stdin=nc\0" \
"stdout=nc\0" \
"stderr=nc\0" \
"conscmd1=run nc\0" \
"conscmd2=run ser\0" \

and change them to:

"stdin=serial\0" \
"stdout=serial\0" \
"stderr=serial\0" \
"conscmd1=run ser\0" \
"conscmd2=run nc\0" \

Change the default boot command to boot from flash

Search for the lines containing:

"bootcmd1=run hdboot;run flboot\0" \
"bootcmd2=run flboot\0" \

and change them to:

"bootcmd1=run flboot\0" \
"bootcmd2=run hdboot;run flboot\0" \

U-Boot in action

This section covers U-Boot in action

Standard Boot Sequence

If you have installed U-Boot as described above, and connect to it it via nc to watch the default boot, and you have a suitable kernel image installed at /boot/uImage on the hard disk, you will see messages along the lines of the following:

U-Boot 1.2.0 (Apr 10 2007 - 19:13:32) LinkStation HG / KuroBox HG
stdin :   nc
stdout:   nc
stderr:   nc
IDE:   Bus 0: .OK
  Device 0: Model: WDC WD3200JB-00KFA0 Firm: 08.05J08 Ser#: WD-WCAMR3092080
            Type: Hard Disk
            Supports 48-bit addressing
            Capacity: 305245.3 MB = 298.0 GB (625142448 x 512)
Boot in 01 seconds ('s' to stop)...
Loading 0:1:boot/uImage

1893924 bytes read

2387 bytes read
## Booting image at 00800000 ...
   Image Name:   Linux-
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    1893860 Bytes =  1.8 MB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
   Booting using flat device tree at 0x7f0000

Useful U-Boot commands

If you press 's' and Enter at the appropriate point to stop U-Boot from attempting to load a kernel, then commands tht may prove to be useful are:


This will list out all the environment variables. Many of them will contain useful information as to how this particular version of U-Boot has been customised, and include preset commands that might be useful.

run command

Run the commands that are stored in environment variable command


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