Building Kubos Linux for the ISIS-OBC¶
This supplementary document covers specific features and components of Kubos Linux for the ISIS-OBC.
The Kubos Linux Overview doc covers the major components of Kubos Linux.
Additionally, this document covers the steps required in order to build Kubos Linux.
The ISIS-OBC Quickstart Guide should have been packaged with the iOBC and is a useful document for learning what each of the hardware components are, how to connect them, and what drivers need to be installed to support them.
The ISIS bootloader lives in the very beginning of the NOR flash. It should come pre-loaded on the board and should not need to be modified. It initializes the memory hardware and then copies U-Boot into the SDRAM and starts its execution.
If for some reason this bootloader needs to be reloaded, the relevant instructions can be found in section 8.1 of the ISIS-OBC Quickstart Guide.
The software tool used to program the iOBC’s NOR flash storage area.
The ISIS-OBC SDK includes the SAM-BA application. You should install this version, rather than the default Atmel version, since it is packaged with several iOBC configuration files which are required to successfully connect to the board.
Kubos Linux Build Process¶
If for some reason you want or need to modify and rebuild the Kubos Linux components, follow the steps in this section.
Kubos Linux should be built from within an instance of the Kubos SDK or some other native Linux environment.
Build the OS Files¶
The OS files cannot be built using a synced folder in a Vagrant box (or regular VM). VirtualBox does not support hard links in shared folders, which are crucial in order to complete the build.
In order to build Kubos Linux, two components are needed:
- The kubos-linux-build repo - Contains the configurations, patches, and extra tools needed to build Kubos Linux
- BuildRoot - The actual build system
These components should be setup as children of the same parent directory. There are several commands and variables in the build process which use relative file paths to navigate between the components.
After the environment has been set up, all build commands will be run from the BuildRoot directory unless otherwise stated.
To set up a build environment and build Kubos Linux:
Create a new parent folder to contain the build environment
$ mkdir kubos-linux
Enter the new folder
$ cd kubos-linux
Download BuildRoot-2019.02.2 (more current versions of BuildRoot may work as well, but all testing has been done against 2019.02.2)
All Kubos documentation will refer to v2019.02.2, which is the latest version of the LTS release at the time of this writing.
$ wget https://buildroot.uclibc.org/downloads/buildroot-2019.02.2.tar.gz && tar xvzf buildroot-2019.02.2.tar.gz && rm buildroot-2019.02.2.tar.gz
Pull the kubos-linux-build repo
$ git clone http://github.com/kubos/kubos-linux-build
Move into the buildroot directory
$ cd buildroot-2019.02.2
Point BuildRoot to the external kubos-linux-build folder and tell it to build the iOBC.
You will need to build with
sudo if you are using the default iOBC
configuration, since it points the output toolchain to “/usr/bin/iobc_toolchain”,
which is a protected directory.
$ sudo make BR2_EXTERNAL=../kubos-linux-build at91sam9g20isis_defconfig
$ sudo make
The full build process will take a while. Running on a Linux VM, it took about an hour. Running in native Linux, it took about ten minutes. Once this build process has completed once, you can run other BuildRoot commands to rebuild only certain sections and it will go much more quickly (<5 min).
BuildRoot documentation can be found **here**
The generated files will be located in buildroot-2019.02.2/output/images. The relevant files are:
- uboot.bin - The U-Boot binary
- at91sam9g20isis.dtb - The Device Tree Binary that Linux uses to configure itself for the iOBC
- kubos-linux.tar.gz - A compressed file containing the complete Kubos Linux SD card image
Changing the Output Toolchain Directory (optional)¶
If you would like to build your toolchain in somewhere other than the
“/usr/bin/iobc_toolchain” directory, update the
BR2_HOST_DIR variable in the
If you would like BuildRoot to just build the toolchain locally, you may remove
BR2_HOST_DIR variable entirely. The toolchain will then be built under the
main “buildroot-2019.02.2” directory in a new “output/host” folder.