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This guide shows how to install Debian on a USB drive and boot Javelin directly from it, using either the stock kernel and module binaries from the original firmware or a customized kernel built from the source released by Patriot.


Debian is a good choice because it is one of the few distributions that supports PowerPC at all and because there are no space constraints in this use case (4Gb USB sticks are commonplace). There is little point to struggle with tiny distros like OpenWRT or Optware when you can just have the convenience of Debian repositories. The Embedian project has been terminated for the same reason. The "small" distributions decrease the disk usage of the root file system but have practically no bearing on runtime resource usage. A fresh Debian system ran literally nothing except kernel threads, init, getty and bash.

Re-using the stock kernel binary or compiling the exact version released by Patriot has the disadvantage that it is not the bleeding edge version, but have the advantage that the device hardware is practically guaranteed to function as completely and correctly as with stock firmware (particularly thermal monitoring, fan speed, power-saving features, etc.). The closed-source t3sas driver for the Promise SATA controller would also work, however it is not recommended.

The following procedure does not introduce anything particularly new to the findings by BadIntensions, senomoto, and everyone else, except maybe the LED handling ;). The Debian installation is standard procedure.

Root file system

All commands are on a Debian-based host system as root user, which can be done using sudo before each command or by switching user to root by

$ su -

Initialize the root file system (first phase of bootstrap):

# apt-get install debootstrap
# mkdir jav-rootfs
# debootstrap --arch=powerpc --foreign --variant=minbase wheezy jav-rootfs/

Create device nodes for serial console:

# mknod jav-rootfs/dev/ttyS0 c 4 64
# mknod jav-rootfs/dev/console c 5 1

Note: /dev/console is needed for first boot to /bin/sh and /dev/ttyS0 is needed for normal boot to init.

Create 'inittab' from a template:

# cp jav-rootfs/usr/share/sysvinit/inittab jav-rootfs/etc/inittab

Edit jav-rootfs/etc/inittab to comment all getty lines that end with tty# (since we have no screen), such as:

1:2345:respawn:/sbin/getty 38400 tty1

and uncomment the line with ttyS0 and change its baudrate from 9600 to 115200 to get:

T0:23:respawn:/sbin/getty -L ttyS0 115200 vt100

Set hostname (otherwise it defaults to host''s hostname):

# echo javelin > jav-rootfs/etc/hostname

Expose the root file system via NFS:

# apt-get install nfs-kernel-server
# ln -s $PWD/jav-rootfs /export/jav-rootfs
# echo '/export/jav-rootfs *(rw,nohide,insecure,no_subtree_check,no_root_squash,async)' >> /etc/exports
# service nfs-kernel-server restart

To limit connections to LAN (if you are not safely behind a NAT), replace * with an ip range like

UART connection

Theoretically, it is possible to develop a procedure that does not require a UART connection by modifying the U-Boot environment settings stored in the NAND memory manually and overwriting the old settings in NAND. However, even if that succeeds, any unrelated issues that might come up during kernel boot or in early userspace init would be near impossible to diagnose without a console. Packaging an uber-user-friendly solution that would work out-of-the box without requiring a UART purchase and setup might be feasible, but is not for me to do.

Get the 4-pin JST connector discovered by BadIntensions.

Get a USB->UART 3.3v adapter (most commonly based on FTDI chip). To hook the JST connector to the UART-to-USB cable I would get a 0.1'' header and solder the wires from the JST connector to the header. Only the TX, RX, and GND (three wires) need to be connected. VCC should NOT be connected, it is 5v on many USB->UART cables, but the VCC on the Javelin board is 3.3v. The pinout from BadIntension''s picture with pins numbered left-to-right:

Javelin [pin] -> UART-to-USB cable
TX       [1]  -> RX
GND      [2]  -> GND
RX       [3]  -> TX
VCC      [4]  -> no connection


Connect the USB->UART cable into host and check that it is detected, i.e. that a /dev/ttyUSB0 device exists. If it does not, then check dmesg and lsusb. Open a terminal client, like screen (or minicom):

# screen /dev/ttyUSB0 115200


There are two options for serving the root file system (created in the above steps):

  • NFS from any Linux host on a local LAN
  • USB drive

The NFS option is described step-by-step below, because this is the approach I took.

For the USB option (not tested), partition the drive (see Bootable USB drive), copy jav-rootfs to the system partition (same section). Then, insert USB stick into Javelin. In U-boot prompt, set bootargs to contain root=/dev/sda3 and init=/bin/sh. Then,run nandboot` to boot the kernel stored in NAND (there is no kernel on the USB stick yet!), but with the root file system from the USB stick. Then, continue with finishing bootstrap (see end of section NFS boot: first stage).

NFS boot: first stage

Plug in the Javelin into a power socket. You should immediately see output from UART. Press Ctrl-C immediately to abort autoboot. Then, tell U-Boot to boot with your rootfs via NFS as follows. Edit the following ip addresses according to your local network (on mine, host system is at and Javelin is requested to be at The stock kernel was compiled without CONFIG_IPCONFIG*, so have to assign IP statically, autoconfiguration using DHCP won''t work.

# setenv ipaddr
# setenv gatewayip
# setenv serverip
# setenv rootpath /export/jav-rootfs

Optionally commit the above (harmless) environment changes to the NAND to not have to re-enter them on subsequent couple of boots:

# saveenv

Modify kernel cmd line arguments and boot:

# setenv addtty ${addtty} init=/bin/sh
# run nfsboot

Note: nfsboot overrwrite bootargs, so need to either modify nfsboot or append to addtty, which is shorter.

Troubleshooting: Warning: unable to open an initial console. from /bin/sh appears when there is no /dev/console device node. See above.

Remount root file system as read-write:

# mount -o remount,rw /

Finish the bootstrap in the shell that the device booted into:

# debootstrap/debootstrap --second-stage

Set root password and exit shell to reboot, and as it begins to boot catch U-Boot with Ctrl-C to get to U-Boot prompt:

# passwd
# exit

NFS boot: second stage

Tell U-Boot to boot into normal mode (init) but still with NFS root fs:

# run nfsboot

Troubleshooting: if after kernel log you see output from init like INIT: version 2.88 booting, but no login prompt appears, then something went wrong with /etc/inittab or mknod for /dev/ttyS0 in the steps above.

Login as root and add package repo for apt:

# echo 'deb wheezy main' >> /etc/apt/sources.list
# apt-get update

In this boot the Internet connection should exist by virtue of the ip arg on the kernel cmd line. If you have trouble resolving domain names, then try

# echo 'nameserver' >> /etc/resolv.conf

Next boot will not have the ip kernel arg, so we need to configure networking. Replace with your network addresses (NOTE: dhcp here did not work):

# apt-get install net-tools ifupdown
# cat >>/etc/network/interfaces <<EOF
> auto eth0
> iface eth0 inet static
> address
> netmask
> gateway

Install udev, which monitors hardware drivers and creates device nodes automatically, and is necessary to enable specifying the root fs by LABEL as we will do shortly:

# apt-get install udev

Troubleshooting: this warning is printed during init, but whatever is broken did not bite so far (when building custom kernel, we get rid of this warning):

[warn] CONFIG_SYSFS_DEPRECATED must not be selected ... (warning).
[warn] Booting will continue in 30 seconds but many things will be broken ... (warning).

udevd[1313]: failed to execute '/sbin/modprobe' '/sbin/modprobe -b platform:ppc4xx_gpio': No such file or directory

Reboot and catch U-Boot prompt with Ctrl-C:

# reboot

This time we want to boot with MTD partitions being accessible:

# setenv addtty ${addtty} ${mtdparts}
# run nfsboot

First, we will get a working bootable setup using the stock kernel shipped with the Javelin extracted from the NAND. A later section will cover an option to customize the kernel configuration and build it from source.

Get the modules from the stock ramdisk (message from gunzip about trailing garbage is because we copied the whole partition instead of the image, it is ok):

# dd if=/dev/mtd5ro of=stock-rootfs.img.gz bs=64 skip=1
# gunzip stock-rootfs.img.gz
# mkdir /mnt/stock-rootfs
# mount -t ext2 -o loop,ro stock-rootfs.img /mnt/stock-rootfs
# mkdir -p /lib/modules/$(uname -r)
# cp /mnt/stock-rootfs/lib/modules/*.ko /lib/modules/$(uname -r)/

Create a new ramdisk for Debian with the usb_storage module, which is needed by the kernel to mount a root file system from the USB drive, and with udev, which is needed for refering to the root filesystem on the kernel command line (ignore the warnings from update-initramfs about nonexistant modules.{order,builtin}):

# apt-get install initramfs-tools
# dpkg-reconfigure udev
# cat > /etc/initramfs-tools/hooks/usb-storage <<EOF
> #!/bin/sh
> . /usr/share/initramfs-tools/hook-functions
> manual_add_modules usb_storage
# chmod +x /etc/initramfs-tools/hooks/usb-storage
# update-initramfs -c -k $(uname -r) -b $PWD

Package the ramdisk into a U-Boot image:

# apt-get install u-boot-tools
# mkimage -T ramdisk -A powerpc -O linux -n "initramfs-$(uname -r)" -C none -d initrd.img-$(uname -r) ramdisk.img

Extract the stock kernel and DTB images from NAND:

The bare minimum needed are the module binaries (which we already packaged into the ramdisk above), since the kernel and the device tree blob (DTB) binaries could be loaded as before from the NAND. However, to boot exclusively from the USB stick without relying on the NAND at all (for example, to be safe against NAND suddenly corrupting on you) we will get the kernel and DTB images:

# dd if=/dev/mtd1ro of=dtb.mtd.img
# dd if=/dev/mtd4ro of=kernel.mtd.img

These are raw partition images, from which the packed uboot images would be extracted (not strictly required, but done in next section on the host system).

Shutdown to release the NFS mounted file system:

# sync
# shutdown -h now

Bootable USB drive

On the host, partition a USB drive (wipes the data that is there!) using fdisk with X replaced with the device letter, which can be found out by running fdisk -l and looking at dmesg. DO NOT SPECIFY YOUR HARDDRIVE''s DEVICE LETTER!

# apt-get install gnu-fdisk
# fdisk /dev/sdX

Example layout:

       Device    Boot      Start         End      Blocks   Id  System
[boot 128M] /dev/sdX1               1          16      128488   83  Linux     
[swap 1G]   /dev/sdX2              17         138      971932   82  Linux swap
[sys  3G]   /dev/sdX3             139         487     2795310   83  Linux     

Create file systems with labels (we will later specify the root file system by label):

# mkfs.vfat -n boot /dev/sdX1
# mkswap -L swap /dev/sdX2
# mkfs.ext3 -L sys /dev/sdX3

Note: U-Boot can read from ext2, but much slower than from FAT (30sec vs 5sec).

Copy the root file system to the USB drive (Javelin should be off!):

# mkdir /mnt/boot /mnt/rootfs
# mount /dev/sdX1 /mnt/boot
# mount /dev/sdX3 /mnt/rootfs
# rsync -a jav-rootfs/ /mnt/rootfs/

Node: the base system turned out to be 252 MB. It will of course grow significantly as we make it more usable in a later section.

Copy the images from rootfs into current directory for convenience:

# cp jav-rootfs/root/*.img .

Extract the U-Boot-packed kernel image from partition image and check that it looks good with mkimage (this extracting is not strictly required, but allows to validate the image and reduces the number of bytes uboot has to load ;):

# imgsize() { echo $((0x$(xxd -p -g 1 -s 12 -l 4 $1) + 64)); }
# dd if=kernel.mtd.img of=kernel.img bs=1 count=$(imgsize kernel.mtd.img)
# mkimage -l kernel.img

The DTB image is not a U-Boot image, so its length is not stored in the header, but again it''s harmless to copy the whole partition, just rename it for consistency:

# cp dtb.mtd.img dtb.img

Copy all images for U-Boot to boot partition of the USB drive (mounted above):

# cp kernel.img dtb.img ramdisk.img /mnt/boot/

Unmount the USB drive:

# umount /mnt/{boot,rootfs}

USB Boot

Plugin the USB drive into Javelin (only the right-hand side port works on my unit for some reason), open the terminal with the UART connection (see UART Connection above), plugin Javelin into power socket, and once U-Boot output shows up, press Ctrl-C to stop autobooting.

Tell U-Boot to boot from the USB drive (just this time) and commit the newly defined commands (harmless):

# run enable_ext
# setenv usbargs 'setenv bootargs root=LABEL=sys'
# setenv usbboot 'run enable_ext;run usbargs mtdargs addtty;fatload usb 0:1 0x1200000 kernel.img;fatload usb 0:1 0x1b00000 ramdisk.img;fatload usb 0:1 0x1a00000 dtb.img;bootm 1200000 1b00000 1a00000'
# saveenv

Try out booting from the USB drive:

# run usbboot

Once you have verified that the boot succeeds all the way to the login prompt and the shell, reboot, catch U-Boot with Ctrl-C again, and finally make the default automatic boot be the USB drive boot:

# setenv real_bootcmd 'run usbboot'
# saveenv

If you ever want to boot the stock firmware, get to U-Boot prompt and execute run nandboot. Execute setenv real_bootcmd run nandboot to make the choice permanent.

Userspace: basic system setup

Apt needs a dialog frontend, so before anything else install it:

# apt-get install apt-utils dialog

Before installing anything else, it''s good to have a locale generated, install this and when it asks, select (for example) en_US.UTF-8 from the list and as the default:

# apt-get install locales
# dpkg-reconfigure locales
# echo LANG=en_US.UTF-8 > /etc/locale.conf

Get yourself an editor (for example nano or vim) and remember to add full list of repos to /etc/apt/sources.list and apt-get update.

Install ssh and certificates (should not need the UART dongle starting now):

# apt-get install ssh ca-certificates

Create a user and add it to sudo group and install sudo:

# apt-get install sudo
# adduser johndoe
# usermod -a -G sudo johndoe

Add the usb drive partitions to /etc/fstab, the following example is for the disk layout given in the preceding section:

#<file system>          <dir>   <type>  <options>       <dump>  <pass>
LABEL=sys               /       ext3    defaults        1       1
LABEL=swap              swap    swap    defaults        0       0
LABEL=boot              /boot   vfat    defaults        1       1

For some reason swap created earlier on the host system is not detected by the Javelin, so re-create it on the Javelin (replace X with the letter of the USB drive that the Javelin assigned to it -- THIS IS NOT ON THE HOST SYSTEM):

# mkswap -L swap /dev/sdX2

Custom kernel

To customize the kernel configuration, you can build the kernel yourself. The version released by Patriot as part of GPL compliance ( builds and boots smoothly with the Device Tree Blob (DTB) extracted from NAND earlier. Getting a more recent mainline kernel to work is likely to be very very difficult. Also, it is easiest to compile natively as opposed to getting a cross-compilation toolchain working. Build time is on the order of hours.

SSH into your newly-setup Javelin system, and get the kernel source (mirrored here), and install build dependencies:

# apt-get install unrar-free
# wget
# unrar -x JV4800p_GPL_Source_v1.0.rar
# cd GPL_Source
# tar xf linux-2.6.32
# cd linux-2.6.32
# apt-get build-dep linux
# apt-get install libncurses5-dev

Configure the kernel for native build:

# export CROSS_COMPILE=""
# make menuconfig

In the menu, using the search function (/):

  • set CONFIG_LOCALVERSION to a suffix appended to the kernel version, to distinguish your customized kernel
  • enable CONFIG_PPC_DISABLE_WERROR: to make it build at all
  • enable CONFIG_USB_STORAGE: to boot from root file system on USB drive
  • enable CONFIG_SATA_AHCI: to access hard drives as block devices (see section on SATA)
  • disable CONFIG_SYSFS_DEPRECATED_V2: to get rid of warning and delay in boot issued by the Debian userspace
  • whatever else you want to customize

Build the kernel and install the modules (only one by default: sci_wait_scan.ko, which can't be built-in and recommented by comments in Kconfig to be enabled):

# make
# sudo make modules_install
# cd ..

Backup the currently booted kernel image:

# cp /boot/kernel.img{,.bak}
# cp /boot/ramdisk.img{,.bak}

Package the kernel into a uBoot image:

# objcopy -O binary linux-2.6.32/arch/powerpc/boot/vmlinux.strip vmlinux.bin
# gzip -v9 vmlinux.bin
# mkimage -A powerpc -O linux -T kernel -C gzip -n "Linux-" -d vmlinux.bin.gz /boot/kernel.img

Create the ramdisk, and package it into a uBoot image:

# cd ..
# sudo update-initramfs -c -k -b $PWD
# mkimage -T ramdisk -A powerpc -O linux -n "initramfs-" -C none -d initrd.img- /boot/ramdisk.img

The Device Tree Blob (DTB) necessary for boot was extracted from NAND in an earlier step of this guide, and should be in /boot/dtb.img.

Mounting the stock NAND partitions

For some reason udev creates the /dev/mtd* device nodes, but not the /dev/mtdblock* nodes, which are needed for mounting the NAND partitions. Fixed by writing an init script that creates the nodes via mknod:

# apt-get install wget
# wget -O /etc/init.d/mtdblock
# chmod +x /etc/init.d/mtdblock
# update-rc.d mtdblock defaults

To mount the partitions from NAND, add the following to /etc/fstab:

# noauto is important since fstab is "executed" before the mtdblock
# init script that creates the /dev/mtdblock* device nodes
/dev/mtdblock6  /mnt/mtd/usr/img jffs2  noauto,user,ro  0       0
/dev/mtdblock9  /mnt/mtd/app/img jffs2  noauto,user,ro  0       0

# These can only be mounted after the above have been mounted
/mnt/mtd/usr/img/usr_sqfs /mnt/mtd/usr/fs squashfs noauto,user,ro 0     0
/mnt/mtd/app/img/app_sqfs /mnt/mtd/app/fs squashfs noauto,user,ro 0     0

Create the mount directories:

# mkdir -p /mnt/mtd/{usr,app}/{img,fs}

Create a couple extra loop devices to be able to mount both app and usr at the same time (and maybe something else too), loop0 exists by default:

# mknod /dev/loop1 b 7 1
# mknod /dev/loop2 b 7 2

Then, to mount the file system, use two steps, for example for usr fs:

# mount /mnt/mtd/usr/img
# mount /mnt/mtd/usr/fs

Note: mounting as regular user works, but unmounting strangely complains that "mount disagress with the fstab" unless you are root (incl, via sudo).


Temperature monitoring and fan control is done by the w83l786ng chip. The standard sensors utility reads it nicely:

# apt-get install lm-sensors
# sensors

Fan control based on temperature is setup entirely in the kernel driver for the monitoring chip, so it works without doing anything in userspace.


In auto-boot mode U-Boot sets the system status LED to red. The stock firmware userspace turned it to blue once booted. To replicate this, we can make use of ledctl utility from the stock firmware and an init script.

# mount /mnt/mtd/usr/img
# mount /mnt/mtd/usr/fs
# cp /mnt/mtd/usr/fs/bin/ledctl /usr/local/bin/
# wget -O /etc/init.d/system-status-led
# chmod +x /etc/init.d/system-status-led
# update-rc.d system-status-led defaults

Edit the system-status-led if you want the LED completely off instead of blue.

Presumably, the ledctl binary creates a device node for ppc4xx_gpio char device and does I/O on it. To avoid using a binary, it should be possible to write your own equivalent script. It might help to look through the driver code in drivers/char/ppc4xx_gpio.c (in source tree released by GPL mirror) and through resources on GPIO on Linux.


Javelin contains the following SATA hardware:

  • Promise PDC42819 SATA/SAS RAID Controller hooked up to the PCI Express bus

  • Synopsys DesignWare Cores SATA Controller (DWC) built into the AMCC 460EX SoC (presumably this serves the eSATA port on the back)

Output from lspci:

81:00.0 RAID bus controller: Promise Technology, Inc. PDC42819 [FastTrak TX2650/TX4650]

The driver for DWC is sata_dwc and is present among the module binaries copied earlier, so it should work out of the box once you attach a drive to the port on the back, as suggested by dmesg | grep -i dwc output:

sata-dwc sata-dwc.0: id 0, controller version 1.82
sata-dwc sata-dwc.0: DMA initialized
sata-dwc sata-dwc.0: **** No neg speed (nothing attached?)

There are two drivers for Promise PDC42819:

  1. The Promise proprietary ("partially open source") FX2650/4650 driver: in t3sas module

    The FX2650/4650 user manual gives a comprehensive description of what it supports.

    This a "fake RAID" controller. IIUC, the biggest problem is that once you create a RAID array using this driver, only this driver is capable to interpret the data from the drives (BAD!). Also, to use the drives at all you need the vendor's user space tools (Promise WebTRACK).

    With t3sas module loaded, the i2arytool in stock usr fs sees the drives (e.g. with i2arytool extlist 0). So, it probably is feasible to make use of this Promise driver in this Debian install. However that is an unrecommended dead-end pursuit. Maybe some kind of performance gain could be extracted, but one would need to hit a real performance bottleneck in one's use-case before even considering it.

  2. AHCI generic SATA driver in ahci module

    This is a generic driver that supports multiple chipsets. It exposes the drives as raw block devices, with devices nodes created at /dev/sd* by udev as usual. This is the way to go. If RAID is desired, portable Linux software RAID should work fine.

    The ahci module binary is not included in the original firmware, but takes a few quick minutes to build as a kernel module. If you built your own kernel according to instructions above, then ahci is already built into the kernel, and no steps are necessary here.

SSH into your Javelin, follow the first several steps of the section on compiling your own kernel to download the kernel source code and open the kernel configuration menu.

Set CONFIG_SATA_AHCI=m by finding it in Device Drivers -> Serial ATA -> AHCI. Build the module (crtsavres.o prerequisite is not built automatically for some reason, so build it manually), and install (the warning about symbol versions info seems to be harmless):

# make oldconfig prepare modules_prepare
# make arch/powerpc/lib/crtsavres.o
# make M=drivers/ata modules
# make M=drivers/ata modules_install
# depmod

Blacklist the Promise module to prevent it from claiming the drives:

# echo 'blacklist t3sas' > /etc/modprobe.d/promise-sata-blacklist.conf

The ahci module will be loaded automatically at boot by virtue of depmod+udev and /dev/sd* nodes should become available.


Enjoy your hardware! One day they will sell it ready for use out-of-the-box...


Just in case, images for the stock and my compilation of the kernel along with DTB and ramdisk are available here.


Configs and scripts for Debian on Patriot Javelin S4 NAS






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