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 will be loaded into the upgrade partition of the board. For now, this can be done through the Kubos SDK or by manually copying the package into the upgrade partition.

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 SD card should have been formatted with the correct partitions. If not, refer to the Install the SD Card Files instructions.

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

A Kubos SDK VM should be installed on your host computer and at least one shared folder should be set up. Installation instructions can be found here.


Acquire an upgrade package. For now, this will likely be sent via email from a Kubos engineer. Once an official distribution process has been created this document will be upgraded with the new procedure.

Load the package into a shared folder accessible by your Kubos SDK VM.

Create or navigate to a Kubos SDK project. The content of the project does not matter; it will only be used to flash the package correctly onto the target.

$ kubos init -l fakeproj
$ cd fakeproj

Set the target to the desired Kubos Linux target type.

For example:

$ kubos target kubos-linux-isis-gcc

Build the project. This does not need to complete successfully. The build process just brings in some files and settings that are required in order to flash files to the board.

$ kubos build

Use the kubos flash command to load the package onto your board. Note: You might need to update your config.json file with the appropriate login information to access your board. See the section Updating Credentials for more information.

$ kubos flash /home/vagrant/shared/kpack-{version}.itb

Wait for the transfer to complete. This can take roughly 30 minutes. The transfer rate via serial connection is slow because a) the upgrade packages are large and b) it runs some CRC functions during transfer to ensure that the package does not become corrupted. You should see a progress bar indicating the time remaining for the transfer.

Bytes Sent: 693248/1769379 BPS:8343 ETA 02:08

Refer to the Flash Troubleshooting section if anything goes wrong with the transfer.

Once the transfer has completed successfully, trigger a reboot of the board. This can be done with the Linux reboot command. Once job scheduling has been implemented, you will be able to schedule the desired reboot time.

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 'kernel@1' :crc32+ sha1+
###writing kernel
1154936 bytes written
Processing upgrade 'rootfs@1' :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 Build the OS Files instructions.

Run the Packaging Script

From the ‘kubos-linux-build/tools’ folder, run the kubos-package.sh script. This will create the rootfs.img and kubos-kernel.itb files and then use 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 Packages

If you’d like to customize the package, 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.
  • -s : Sets the size of the rootfs.img file, specified in KB. The default is 13000 (13MB).
  • -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 name of U-Boot that has been built. The default is ‘master’. 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 -s 15000 -i /home/test/custom.its -v 2.0

Distribute the Package

There isn’t currently a central storage location or procedure for upgrade packages, since no official packages have been created yet. This section should be upgraded once something has been implemented.