Installation

The installation guide worked fine. The Wheezy kernel doesn’t work (see next section), so you should install Squeeze. You can get the network install image from here; it is a firmware image that you can upload straight into the firmware update tool in the stock DNS-323 firmware. When you reboot, it will start up an SSH daemon with username installer and password install; SSH into that to begin the install. You can also talk with the installer over a serial port.

Kernels

The reason I’m running the Squeeze kernel (2.6.32) is that newer kernels have various problems with the DNS-323 hardware. Most notably, they panic when scanning the MD disk array (#699667). Other kernel versions that fix that problem have I2C problems controlling the fan (#622325). And the 3.10 kernel in wheeze-backports and 3.11 kernel in Debian Testing (Jessie), have yet another error: they get stuck in a loop trying to talk to the hard drives, receiving errors (or messages they can’t parse) from the hard drives. So it really works best to stick with kernel 2.6.32.

Debian includes a flash-kernel program that you need to run to actually install a new kernel to the flash memory and have it booted. Debian Wheezy automatically runs this when you install a new kernel; Debian Squeeze does not. Just running sudo flash-kernel will flash the most recent kernel and its initramfs to the device’s flash memory. Unfortunately, there isn’t a way to make it flash an old kernel; you have to uninstall all newer kernels so just the one you want to flash is installed, then run it without arguments.

Upgrading to Wheezy

After installing with Squeeze, you can upgrade to Wheezy. To keep the old kernel, with updates from Squeeze (and its long-term support), there are a couple of things to do. First, have entries for both Debian versions in /etc/apt/sources.list:

deb http://debian.osuosl.org/debian/ wheezy main
deb http://debian.osuosl.org/debian/ squeeze main

deb http://security.debian.org/ wheezy/updates main
deb http://security.debian.org/ squeeze/updates main

deb http://debian.osuosl.org/debian/ wheezy-updates main
# no need for squeeze-updates

Then use /etc/apt/preferences to make Squeeze not-preferred, except for kernel packages, where it is strongly preferred:

Package: linux-image-* firmware-linux-*
Pin: release n=squeeze
Pin-Priority: 1001

Package: *
Pin: release n=squeeze
Pin-Priority: 50

# also un-prefer unstable
Package: *
Pin: release a=unstable
Pin-Priority: 50

This will keep your kernel up-to-date from Squeeze on an otherwise up-to-date Wheezy (or Wheezy + Backports) system.

Recovery

I’ve had to get very good at recovering the 323 in the process of identifying a working kernel. Fortunately, the Debian instrutions work pretty well. These instructions are based heavily on those, with some more info to get them working well with newer environments.

To recover, you need a few things:

• A serial cable
• Kermit (available in most Linux distributions)
• The installer image
• dns323-firmware-tools (to extract flashable images from the firmware update image)

The firmware update image that you get from Debian (or from D-Link, if you want to recover the stock firmware) is a FrodoII firmware image. The dns323-firmware-tools let you extract separate uKernel and uRamdisk files from the firmware image that you can flash with Kermit.

New versions of the firmware tools do not work, in my experience. I have been able to get version 0.3 to work (it is tagged in git). Unfortunately, this version only works with Ruby 1.8. If you have a newer Ruby installed, the easiest path is to use JRuby. It maintains Ruby 1.8 compatibility.

So, extract the firmware:

$ git clone https://github.com/mpalmer/dns323-firmware-tools.git
$ (cd dns323-firmware-tools && git checkout 0.3)
$ jruby --1.8 dns323-firmware-tools/splitdns323fw \
    -k uKernel -i uRamdisk netinst.img

Then launch Kermit and set it up to talk to the DNS-323:

$ kermit -l /dev/ttyUSB0 -b 115200
C-Kermit> set carrier-watch off
C-Kermit> set flow-control none
C-Kermit> set handshake none
C-Kermit> set prefixing all
C-Kermit> set streaming off
C-Kermit> set parity none
C-Kermit> c

The last c command starts a serial console connection so you can watch for boot messages.

Boot the device. It will show a boot countdown; while this is going, enter <Space>1 to drop to a bootloader prompt. You then need to bounce back and forth between that prompt and Kermit to flash the firmware:

1. Enter loadb k at the Marvell>> boot loader prompt.
2. Hit C-\ c to escape back to Kermit.
3. In Kermit, type send uKernel. It will send the kernel.
4. Reconnect to the console with c; wait for the Marvell>> prompt again. If the console seems frozen, you can hit Enter.
5. Enter loadb r at the Marvell>> prompt.
6. Escape to Kermit wth C-\ c again
7. Enter send uRamdisk in Kermit
8. After the ramdisk is sent, type c to reconnect and wait for flashing to finish. The console often seems to hang on this for me; hitting Enter wakes it up.
9. Once you have a Marvell>> prompt again, pull the power, plug it back in, and boot.

You now have the installer re-flashed. You can do an install (wiping out existing data) or use the installer image to recover. The Kermit console will let you monitor the installer boot; start into the installer, then hit ‘Go back’ when it starts asking you for passwords, to get to the main installer menu. This will let you do things like ‘Detect disks’, which will make sure the appropriate software to control the Software RAID (and therefore chroot into the real install) is installed.