RAUC¶

Introduction¶

RAUC is a lightweight update client that runs on your embedded device and reliably controls the procedure of updating your device with a new firmware revision.

RAUC is also the tool on your host system that lets you create, inspect and modify update files (”bundles”) for your device.

Please refer to RAUC documentation for a detailed documentation from RAUC.

Yocto Setup¶

Setup a complete Yocto build environment using the karo-minimal DISTRO for your module.

Until now, we only tested rauc with the QSMP* and TXMP* modules. More to come…

Note

QSMP, TXMP use Mainline Yocto BSP Guide

Setup the Yocto build-directory as described in the Yocto guide for your machine.
Add the following to conf/local.conf:
```
DISTRO_FEATURES:append = " rauc"
```
Compile the image.
```
bitbake karo-image-minimal
```
Note

RAUC is only usable for karo-image-minimal or a custom image because the other images are to big to have two rootfs partitions with the same size.
Program your module using uuu and reset it. You can also do your own partitioning of the module. Refer to Custom partitioning and system.conf. By default there are two redundant systems on the board for rauc.
After reset run
```
setenv boot_mode mmc_rauc
saveenv
```
If the boot_mode is set to mmc, the boot script will not be used and rauc can’t switch between partitions.
Boot your board. Run
```
rauc service &
```
on the Linux command prompt on the board to activate rauc.

Host Setup¶

Prerequisites for host PC¶

build-essential

meson

libtool

libdbus-1-dev

libglib2.0-dev

libcurl3-dev

libssl-dev
sudo apt-get install build-essential meson libtool libdbus-1-dev libglib2.0-dev libcurl3-dev libssl-dev

Building rauc for host PC from sources¶

git clone https://github.com/rauc/rauc
cd rauc
meson setup build
meson compile -C build # or 'ninja -C build' on meson < 0.54.0

Install rauc on host PC¶

RAUC can be used directly from the build dir, or optionally be installed.
meson install

Using rauc¶

Start the rauc service on the module¶

Run the following command on the modules linux commandline
rauc service &

Create a bundle on host PC¶

Create a directory with the content that should be installed. For example a new root filesystem.
mkdir content-dir/
cp <path-to-new-rootfs>/rootfs.ext4 content-dir/
Create a manifest describing which image to install where together with some meta info
cat >> content-dir/manifest.raucm << EOF
[update]
compatible=<your-board>    (e.g. txmp-1570)
version=2024-06-14

[bundle]
format=verity

[image.rootfs]
filename=rootfs.ext4
EOF
Let RAUC create a bundle from this
rauc --cert <path-to-cert>/cert.pem --key <path-to-key>/key.pem bundle content-dir/ update-2024-06-14.raucb
In your bsp in the meta-karo-distro layer you can find the key and the cert.
...meta-karo-distro/dynamic-layers/recipes-core/bundles/files/development-1.cert.pem
...meta-karo-distro/dynamic-layers/recipes-core/bundles/files/private/development-1.key.pem
Note

This key and cert is only a development key and cert. For productive usage, please create your own ones.

Install the bundle on the module¶

The created bundle (in the example update-2024-06-14.raucb) needs to be copied to the module to install it. To install the bundle run the following command on the modules linux commandline
rauc install <path-to-bundle>/update-2024-06-14.raucb
After cyptographically verifying the bundle, RAUC will now determine the active slots by looking at the rauc.slot variable. Then, it can select the target slot for the update image from the inactive slots.

When the update is installed completely, we just need to restart the system. U-Boot will then try to boot the newly installed rootfs. The updated slot will be automatically marked good if the boot process was successful.

Custom partitioning and system.conf¶

For creating a custom partitioning and configure rauc to your needs, you should create your own yocto-layer according to “Create Custom Layer" in the Yocto Guide.

The implemented rauc configuration is just an example, you will need to tailor the partitioning and system.conf according to your needs.

We decided to setup a redundant system with the following structure:
├── bootfs
│   └── bootfsB
├── rootfs
│   └── rootfsB
└── userfs
    └── userfsB
If you want to change this, you can edit the uuu.auto script in your deploy directory.

After changing the partitioning, you should copy the system.conf from <your-bsp>/layers/meta-karo-distro/dynamic-layers/recipes-core/rauc/files/ to your own layer: <your-bsp>/layers/meta-mydistro/dynamic-layers/recipes-core/rauc/files/ and chenge it there according to your needs.

For more informations, please refer to RAUC partitioning