OpenWRT Build Notes for HLK-7621

These are the build notes used to build OpenWRT for the HLK-7621.

They're really just based on the excellent documentation provided by OpenWRT, which should be considered the authoritative source.

• Fresh Debian 12.8 AMD64 install. I ran it as a VM and gave it 8 Cores and 32GB RAM.

1. Install prerequisites:

   sudo apt update
   sudo apt install build-essential clang flex bison g++ gawk \
   gcc-multilib g++-multilib gettext git libncurses5-dev libssl-dev \
   python3-setuptools rsync swig unzip zlib1g-dev file wget

2. Clone the source and pull the current version of the feeds:

   # Download and update the sources
   git clone https://git.openwrt.org/openwrt/openwrt.git
   cd openwrt
   git pull
   
   # Select a specific code revision
   git branch -a
   git tag
   git checkout v23.05.5
   
   # Update the feeds
   ./scripts/feeds update -a
   ./scripts/feeds install -a

3. I want to build a matching firmware to current snapshot version for my device. So let's fetch the "official" configuration.

   $ wget https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/config.buildinfo -O .config

4. Deselect the targets we're not interested in. I also used this an opportunity to add some packages I wanted, such as Python3, nano, netatalk, kmod-appletalk, etc.

   make menuconfig

   Then start the build...

   make download # download code and tools
   make -j8 # will take a while!

   On my machine the build took a couple of hours, and included the SDK, etc. This should give us an image that matches the one produced by the OpenWRT image builder. The resulting image is in ./bin/targets.

5. Use the sysupgrade image to reflash the device. I haven't built a script to set the network config the way I want it, so you'll need to log in and set the IP address manually.