Building OpenWrt

Introduction

The OpenWrt is a Linux operating system targeting embedded devices. This guide describes how to set up OpenWrt building environment for XpressReal T3 SBC.

System requirement

Operating system

• Ubuntu 24.04/22.04/20.04 LTS
• Fedora 39/40/41
• Debian GNU/Linux 11/12

Minimum Free Disk Space

To build an image for the XpressReal T3, you need a system with at least 20 GB of free disk space.

Minimum System RAM

You will manage to build an image for the XpressReal T3 with as little as 8 GB of RAM on an old system with 4 CPU cores, but your builds will be much faster on a system with as much RAM and as many CPU cores as possible.

System preparation

Ubuntu/Debian Packages

Here are the packages needed to build an image on a headless system with a supported Ubuntu or Debian Linux distribution:

sudo apt update
sudo apt install build-essential clang flex bison g++ gawk \
gcc-multilib g++-multilib gettext git libncurses-dev libssl-dev \
python3-distutils python3-setuptools rsync swig unzip zlib1g-dev file wget

Fedora Packages

Here are the packages needed to build an image on a headless system with a supported Fedora Linux distribution:

sudo dnf --setopt install_weak_deps=False --skip-broken install \
bash-completion bzip2 file gcc gcc-c++ git-core make ncurses-devel patch \
rsync tar unzip wget which diffutils python3 python3-setuptools perl-base \
perl-Data-Dumper perl-File-Compare perl-File-Copy perl-FindBin \
perl-IPC-Cmd perl-JSON-PP perl-lib perl-Thread-Queue perl-Time-Piece

Shell

You need to ensure you are using bash as your default $SHELL.

Fetch OpenWrt source

Fetch OpenWrt source code from GitHub repository:

git clone https://github.com/XpressReal/openwrt.git
cd openwrt

Update and install feeds

Update and install the package feeds:

./scripts/feeds update -a
./scripts/feeds install -a

Configure the build system

You can start with the default configuration for XpressReal T3:

cp defconfigs/xpressreal_t3_rtd1619b_defconfig .config

Then run make menuconfig to customise the configuration as needed:

make menuconfig

Make sure to select the correct Target System, Subtarget, and Target Profile for XpressReal T3 if not already set:

• Target System (RealTek DHC)
• Subtarget (RealTek RTD1619B boards)
• Target Profile (XpressReal T3) You can also customise other options such as additional packages and features according to your requirements.

Build the image

Once you have configured the build system, you can start the build process by running:

make -j$(nproc)

This will compile the OpenWrt firmware image for the XpressReal T3 based on your configuration. The build process may take some time depending on your system’s performance and the selected configuration. After the build is complete, you can find the generated firmware image in the bin/targets/rtd/rtd1619b/ directory within the OpenWrt source tree. The firmware image file will be named something like openwrt-rtd-rtd1619b-rtd_xpressreal-t3-<fs_type>-sdcard.img.gz.