Upgrading Kubos Linux


Kubos Linux upgrades are distributed as kpack-{YYYY.MM.DD}.itb files. ITB stands for ‘Image Tree Blob’ and allows Kubos to utilize the existing DFU utility currently available in U-Boot.

Within each file will be a new version of the kernel image and root filesystem.

To upgrade a board currently running Kubos Linux, an upgrade package should be loaded into the upgrade partition of the board. For now, this is done by manually copying the package into the upgrade partition and then setting the kubos_updatefile environment variable.

Once the board is rebooted, U-Boot will take the package and then install each component into the appropriate partition (kernel/rootfs). If installation completes successfully, then the board will be rebooted and then boot into the new version of Kubos Linux.

The overall flow looks like this:

Kubos Linux Upgrade

Kubos Linux Upgrade


User files should not be impacted by upgrade installation as long as they remain under the /home directory. This directory maps to the user space partition.

However, some future releases may cause the Kubos libraries to undergo significant changes. In this case, backwards compatilibity is not guaranteed and user applications may need to be rebuilt.

Upgrade Installation


The host computer should be connected to the target board, which should be on and running Kubos Linux.


Contact a Kubos team member for an upgrade file for your desired Kubos Linux version. Alternatively, create one yourself following the directions in the upgrade creation section.


Not all releases can be installed via upgrade. Some releases contain changes which massively alter the system, causing a full install to be required instead.

Transfer the package to the target system using scp or other file transfer method of choice:

$ scp kpack-{version}.itb kubos@{target_ip}:/upgrade/

Once the transfer has completed successfully, log into the board and set the kubos_updatefile variable with the name of the upgrade file like so:

$ fw_setenv kubos_updatefile kpack-{version}.itb

Now, trigger a reboot of the board. This can be done with the Linux reboot command.

When the board boots into U-Boot, the new package will be detected and loaded. If the loading is successful, the board will reboot into the newly installed Kubos Linux. The U-Boot console messages will look similar to this:

Processing upgrade '[email protected]' :crc32+ sha1+
###writing kernel
1154936 bytes written
Processing upgrade '[email protected]' :crc32+ sha1+
##########################Un-Protected 1 sectors
Erasing Flash...
. done
Erased 1 sectors
Writing to Flash... done
Protected 1 sectors
resetting ...

Upgrade Rollback

If for some reason you need to rollback to a previous version of Kubos Linux, you don’t need to reflash the board with the correct upgrade package. Previous packages are not deleted once they have been loaded. As a result, you can simply specify which package you would like to boot into and then restart your system.

From the Kubos Linux shell:

$ fw_setenv kubos_updatefile kpack-{desired version}.itb
$ reboot

Upgrade Creation

This section is for developers who have made changes to Kubos Linux and want to generate an upgrade package.


Build the new OS. Refer to the appropriate Building Kubos Linux for the {OBC} instructions.

Run the Packaging Script

From the ‘kubos-linux-build/tools’ folder, run the kubos-package.sh script. This takes the rootfs.img and kubos-kernel.itb files which were created during the build process and uses the kpack.its file to bundle them into an *.itb file. This is the file that will be distributed to customers when an upgrade is needed.

The automatically generated naming convention for the package is kpack-yyyy-mm-dd.itb

Custom Files

If you’d like to customize the upgrade file, there are a few different options available through the script:

  • -t {target} : Required Specifies the name of the target board, as named in the corresponding kubos-linux-build/board/kubos/{target} directory.
  • -i : Sets the name and location of the input *.its file. Use if you want to create a custom package. The default is kpack.its.
  • -o {folder} : Specifies the name of the buildroot output folder. The default is ‘output’
  • -v : Sets the version information for the package. The output file will be kpack-{version}.itb.
  • -b {branch} : Specifies the branch/version name of U-Boot that has been built. The default is ‘1.1’. This option should not need to be used outside of development. U-Boot contains files which are used in the package generation process.

For example:

$ ./kubos-package.sh -t beaglebone-black -i /home/test/custom.its -v 2.0