OTA is a method that enables lossless system upgrades for devices, allowing new features to be remotely deployed on products. The OTA upgrade package can not only be downloaded via the network but also used to upgrade the device after being downloaded to an SD card or a USB flash drive.

This article will introduce the specific implementation method of using OTA to upgrade the system on the Linux 5.4.70 system through the Forlinx Embedded OKMX8MP-C development board.

1. Environment Setup

1.1 Download the 22.04 Image of the Compilation Environment

Since RAUC version 1.6 is required, the 22.04 ISO image needs to be downloaded.

Download URL: https://mirrors.tuna.tsinghua.edu.cn/ubuntu-releases/22.04/

1.2 Modify the GCC Version of the Development Environment

1.2.1 Modify the apt Source

sudo gedit /etc/apt/sources.list

1.2.2 Add the Source at the End of the File

deb [arch=amd64] http://archive.ubuntu.com/ubuntu focal main universe

1.2.3 Update the source

sudo apt update

1.2.4 Install GCC

sudo apt install gcc-7 g++-7

1.2.5 Back up the original GCC and G + +

sudo mv /usr/bin/gcc /usr/bin/gcc.bak
sudo mv /usr/bin/g++ /usr/bin/g++.bak

1.2.6 Link to gcc-7

sudo ln -s /usr/bin/gcc-7 /usr/bin/gcc
sudo ln -s /usr/bin/g++-7 /usr/bin/g++

1.2.7 Install and test

gcc --version
g++ --version

GCC test run results:

G + + test run results:

1.3 Install the rauc tool

sudo apt install rauc

2. Source code configuration

2.1 EMMC partition

Need to modify the source code OK8MP-linux-fs/rootfs/etc/init.d/Init.sh

#! /bin/sh
	
	
	## add forlinx user 
useradd -k /etc/skel -m -U forlinx -s /bin/bash
passwd forlinx <<EOM
forlinx
forlinx
EOM
DEVICE="/dev/mmcblk2"
# Create the partition
fdisk $DEVICE <<EOF
n
p
3
13818240
13988608
t
3
c
n
p
4
13988609
30589000
w
EOF
# Refresh the partition table
partprobe
# Output partition information
lsblk $DEVICE
resize2fs /dev/mmcblk2p2
/usr/bin/fltest_runRefreshMatrix.sh
## delete Init.sh
sed -i "s/\/etc\/init.d\/Init.sh//g" /etc/rc.local
rm -f /etc/init.d/Init.sh
sync

2.2 Decompression of rauc and dependent tools

（1）Decompress under liblz4.tar.bz2在/OK8MP-linux-sdk/OK8MP-linux-fs/rootfs/usr/lib

tar -xvf liblz4.tar.bz2

（2）Decompress fw_setenv.tar.b z2 under /OK8MP-linux-sdk/OK8MP-linux-fs/rootfs

tar -xvf  fw_setenv.tar.bz2

（3）Decompress unsquashfs.tar.bz2 under /OK8MP-linux-sdk/OK8MP-linux-fs/rootfs

tar -xvf  unsquashfs.tar.bz2

（4）Decompress yocto-rauc-1.5.1.tar.bz2 under /OK8MP-linux-sdk/OK8MP-linux-fs/rootfs

tar -xvf  yocto-rauc-1.5.1.tar.bz2

2.3 Modifying the tool configuration

2.3.1 Modify the fw_env.config to specify the env base addr

/OK8MP-linux-sdk/OK8MP-linux-fs/rootfs/etc/fw_env.config

gedit fw_env.config

Delete the original content and only add:

/dev/mmcblk2 0x400000 0x2000

2.3.2 Modify the rauc configuration file

/OK8MP-linux-sdk/OK8MP-linux-fs/rootfs/etc/rauc/system.conf

gedit system.conf

Note: It is necessary to ensure that the compatibility is consistent with that in the upgrade package and that the partition contents are correct.

2.3.3 Modify the compilation script

forlinx@ubuntu:~/OK8MP-linux-sdk$ gedit tools/fakeroot.fs

This part of the script needs to be commented out:

2.3.4 Modify the mount configuration file

forlinx@ubuntu:~/OK8MP-linux-sdk/OK8MP-linux-fs/rootfs/etc$ gedit fstab

Modify OK8MP-linux-fs/rootfs/etc/fstab as follows：

/dev/mmcblk2p3    /run/media/mmcblk2p3  auto       defaults,sync,noauto  0   0           
/dev/mmcblk2p4    /run/media/mmcblk2p4  auto       defaults,sync,noauto  0   0 

Note: The main purpose here is to prevent the service from automatically mounting the partition and causing the upgrade time partition to be already mounted.

3. Generate an upgrade package

3.1 Full compilation to obtain the required image

forlinx@ubuntu:~/OK8MP-linux-sdk$ . /opt/fsl-imx-xwayland/5.4-zeus/environment-set\up-aarch64-poky-linux 
forlinx@ubuntu:~/OK8MP-linux-sdk$ . environment-setup-aarch64-poky-linux 
forlinx@ubuntu:~/OK8MP-linux-sdk$ ./build.sh all

3.2 Copy the image and key file

Create the rauc folder

forlinx@ubuntu:~$ mkdir rauc

Create the build and bundle folders under the rauc folder

forlinx@ubuntu:~/rauc$ mkdir build
forlinx@ubuntu:~/rauc$ mkdir bundle

Copy the boot. img generated by compiling under images and rootfs.ext4 to the folder of bundleExtract the key file that provides the test to the rauc folder

forlinx@ubuntu:~/rauc$ tar -xvf key.tar.bz2

3.3 Create upgrade package configuration file

Create manifest. raucm upgrade package configuration files in the bundle folder

forlinx@ubuntu:~/rauc/bundle$ gedit manifest.raucm 

The contents are:

[update]
compatible=forlinx-imx8mp
version=r0
description=rauc bundle based on Forlinx-LINUX-5.4.70
build=20240306
[image.rootfs]
filename=rootfs.ext4
[image.boot]
filename=boot.img

3.4 Make upgrade package

Create the script package

forlinx@ubuntu:~/rauc$ gedit run.do_bundle.sh 

The contents are:

#!/bin/sh
if [ -e build/bundle.raucb ]; then
rm build/bundle.raucb
echo "---------------------rm old bundle.raucb-------------------------"
fi
rauc  bundle --debug --cert="development-1.cert.pem" --key="development-1.key.pem"  bundle    build/bundle.raucb

Give the scripts executable permissions:

forlinx@ubuntu:~/rauc$ chmod 777 run.do_bundle.sh

Generate an upgrade package

forlinx@ubuntu:~/rauc$ ./run.do_bundle.sh

The bundle. raucb upgrade package is generated under the build folder.

Note: Pass the bundle. raucb upgrade package to the ext4 partition of the development board, in case of permission problems.

4. System Upgrade

4.1 View system status and upgrade

(1) View compressed package information

(2) View system status

root@OK8MP:~# rauc status

(3) System upgrade

root@OK8MP:~# rauc install bundle.raucb

4.2 Switch the boot partition

View uboot environment variable

root@OK8MP:~# fw_printenv

Configure to start from systme _ 1

root@OK8MP:~# fw_setenv doraucboot 1
root@OK8MP:~# sync
root@OK8MP:~# reboot

View system status after reboot

root@OK8MP:~# rauc status

5. Rollback version

5.1 Reconfigure to system _ 0 boot

root@OK8MP:~# fw_setenv doraucboot 0
root@OK8MP:~# fw_printenv               //Print environment variables
root@OK8MP:~# sync
root@OK8MP:~# reboot

The rauc is upgraded to the alternate replacement of two systems. When upgrading, be sure to pay attention to the partition currently booted by uboot.

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