DSM-G600, DNS-3xx and NSA-220 Hack Forum

If you are prepared to wait a little bit, work is under way to enable booting from USB (and the network) in u-boot. Once this is complete, you should be able to flash a new u-boot to your DNS323, and configure it to boot from wherever you want to.

Network support exists already, although the flash chip is not writable as yet. USB and SATA boot should follow within the next month or so.

HamRadio wrote:

RoganDawes wrote:

Once this is complete, you should be able to flash a new u-boot to your DNS323, and configure it to boot from wherever you want to.

Hi Rogan,

this is very interesting.
Is there a website to stay up-to-date with this project?

This could let me tell u-boot to boot a kernel which could be on an usb device instead of the usual one.

However my problem remains that the kernel, which is on the mtd chip and which is well booted by u-boot with the right command line parameters, doesn't mount the root filesystem that I indicate in those command line boot parameters...

Thank you.

I'm keeping a bit of a log on my progress in the U-Boot page on the DNS-323 wiki, and of course, I'll post here when I have something for others to test.

melon wrote:

Why don't you try to boot via LABEL=foobar? I just edited /etc/fstab and ran 'update-initramfs -u' and it seemed to work fine.

I don't think it could solve my problem, which is to temporarily change the filesystem mounted as root for maintenance purposes (e.g. changing filesystem type, size, etc. etc.).

I could let LABEL=root in /etc/fstab and then put an ext3 usb stick containing a copy of my root filesystem having itself LABEL=root, but the kernel will still boot from the root on /dev/md0 because I cannot remove the hard drives from the system, nor I can "hot-insert" them after the system has booted...

The problem is that the kernel ignores root=/dev/xxx command line parameter, preferring what is inside conf/param.conf in the initramfs configuration, even though usually command line parameters should have higher priority over those in config files...

well the way you are trying to change to root fs is wrong. you just have to change your initrd config.

HamRadio wrote:

Try yourself on your machine, it works fine.

On my laptop yes, on a DNS-323 no, because the initrd is automatically loaded from flash.

Hi,

after some holidays I'm still trying to solve this problem.

I've found that the kernel parameter about which is the root device is stored in the file conf/param.conf inside the initramfs tree, and this information is gathered by the script /usr/share/initramfs-tools/hooks/flash_kernel_set_root reading the content of /etc/fstab. flash_kernel_set_root is normally called by update-initramfs, dpkg-reconfigure linux-image-2.6.xx-orion5x, and perhaps /usr/bin/mkimage.
In fact my conf/param.conf contains:
ROOT="/dev/md0"
The script /usr/share/initramfs-tools/hooks/flash_kernel_set_root belongs to the package flash-kernel, which supports not only our DNS-323 but also various other machines. It seems that the bootloader in some machines do not passes a meaningful root device parameter, and in some others it does, or the parameter itself is absent. In our case u-boot configuration contains /dev/ram, a value which perhaps was used by the original firmware, but for our Debian installations it doesn't mean anything, so the script flash_kernel_set_root has to provide a meaningful root device parameter overriding the fake value passed by the bootloader. It finds out the right value extracting it from /etc/fstab.
The script flash_kernel_set_root has a function, root_type() at line 24, which can "override the root device or merely provide a default root device", depending on the machine type. Our machine, the DNS-323 is the third entry, is among those to "override".
So I could solve my problem simply changing "override" with "default" at the relevant line 33 in /usr/share/initramfs-tools/hooks/flash_kernel_set_root and then running update-initramfs or dpkg-reconfigure linux-image-2.6.xx-orion5x.
However, first of all I'd need a good root device default value in the u-boot configuration, certainly not the actual /dev/ram, and this can easily be done (having a working serial port) modifying "bootargs" parameter of the bootloader configuration, and then saving that configuration permanently by issuing the command "saveenv", as can be seen in the u-boot manual. Once I have this "meaningful" value stored as a default, I could occasionally enter another value to boot from another device, e.g. an usb stick.

Too bad that our friends at D-Link has installed u-boot without saveenv command!

In fact these are the only commands available on my DNS-323:

Marvell>> ?
?       - alias for 'help'
bootm   - boot application image from memory
cp      - memory copy
echo    - echo args to console
erase   - erase FLASH memory
loadb   - load binary file over serial line (kermit mode)
md      - memory display
printenv- print environment variables
run     - run commands in an environment variable
setenv  - set environment variables

As you can see saveenv is missing.

So here I am stuck without a way to save the parameters I'd need.
Perhaps I could dd /dev/mtdblock4 (where u-boot configuration is stored) to a file, edit it with an hex editor like ghex2, and then dd it back on /dev/mtdblock4...
I could also install a full version of u-boot, I wonder if anyone has already done it, perhaps there is a package somewhere on the net for our DNS-323 ready to install...

I don't want to risk bricking my nas, anyone has something better to suggest?

Thanks again.

HamRadio,

I don't quite see why labels won't solve your problem; maybe I'm not understanding your use case. I'm booting my DNS-323 from USB using a label rather than a device id. I have a raid1 array that is being started via /etc/init.d/mdadm-raid (in conjunction with /etc/mdadm.conf which defines my array by UUID, again no device ids). As you noted this is configured via /etc/fstab:

LABEL=storage-root       /               ext3    noatime,errors=remount-ro 0

In my initrd this corresponds to conf/param.conf having this following line (it was autotranslated from the LABEL= syntax by the initramfs scripts):

ROOT="/dev/disk/by-label/storage-root"

I realize you have a different aim (boot from HD regularly, USB for maintenance). What I don't understand is why you can't just set up a boot based on label (say "dns323-root"). Label you hard drive that way and your usb something else (say "dns323-maint") for normal operation. Then when you want to do maintenance, use e2label to swap the labels, reboot and you should come up from usb. When you're done relabel again with e2label to get back to your normal state.

That avoids the u-boot issue altogether although it does rely on having access to the system for relabeling prior to you maintenance activities. The only detail I'm not 100% clear on is whether or not the initramfs portion assembling your raid array (so it can even check the filesystem label) will have any negative impact on this scenario. My setup doesn't do that at all (I never boot from hard drive) so I haven't played around with that.

-Jeff