Building from Source

Building from Source

In one sentence: you never need this to install (the installer downloads ready-made images), but everything can be built from public sources with Docker.

The simple version: the releases are bread from the bakery. This page is the recipe, for when you want to bake it yourself or change an ingredient.

The full, authoritative instructions are in docs/BUILD.md. This page is a map.

What a release contains

File	Contents
mu300-kernel.tar.gz	Linux 5.4.254 Image and modules (with the U30 Air's own), static busybox and logdw, the generic boot ramdisk segment
mu300-kernel-6.18.tar.gz, mu300-kernel-7.2.tar.gz	the mainline kernels and their modules
mu300-ubuntu-rootfs.tar.gz, mu300-ubuntu-26.04-rootfs.tar.gz	Ubuntu 24.04 and 26.04
mu300-openwrt-rootfs.tar.gz, mu300-openwrt-luci-rootfs.tar.gz	OpenWrt 25.12.5, plain and with the control panel
mu300-extra-lang.tar.gz	more web interface languages
mu300-update	the on-device updater
mu300-magisk-*.zip	Magisk installers, one per system and kernel
SHA256SUMS, SHA256SUMS-magisk	checksums

The images contain no proprietary files; the installer takes those from your own device.

How a boot goes

flowchart TD
    LK[LK bootloader, Linux slot] --> K[Kernel + vendor_boot device tree]
    K --> I[initramfs boot/init]
    I --> M[Load 85 vendor modules in a fixed order]
    I --> U[USB gadget: NCM or ECM network + serial console]
    I --> F[Find the Linux disk:<br/>SD card mu300sd, else free eMMC space mu300root]
    F --> S[switch_root into the chosen system]
    S --> V[mu300-vendor: Android modem_control in a chroot]
    S --> L[mu300-lan: USB + Wi-Fi bridge, DHCP/DNS]
    S --> W[Wi-Fi, mobile data, Bluetooth, SSH]

Loading

The build in one step

kernel/build-all.sh    # -> out/Image, out/modules/*.ko, out/modules.builtin*

That builds the 5.4 kernel and its Wi-Fi, Bluetooth and Mali modules from pinned public sources with all patches applied (about 10 minutes on Apple silicon). Then:

• Root filesystems: Ubuntu from rootfs/ (Docker), OpenWrt with openwrt/build-rootfs.sh, the control-panel system with MU300_SYSTEM=openwrt-luci openwrt/build-rootfs.sh.
• Install your own build: ./install.sh --build uses your local kernel outputs and builds the root filesystems instead of downloading them.
• Release: tools/make-release.sh TAG --publish (it refuses to publish an image that contains firmware, Android files, host keys or local settings), or the Release workflow in GitHub Actions.
• Magisk zips: tools/make-magisk-zips.sh RELEASE_DIR OUT_DIR.

Sources

• 5.4 kernel: ZTE's GPL release for the U30 Air, mirrored at dikeckaan/zte-ums9620-kernel-5.4.254.
• Wi-Fi, Bluetooth and GPU drivers: realme C51/C53 AndroidT kernel release (GPL-2.0).
• Mainline 6.18 and 7.2: kernel.org Linux plus the port in upstream/.
• Each release's notes list the exact source commits.

Other distributions

Debian 13, Kali, Arch Linux ARM and ImmortalWrt build from this repository too; how, and what to expect: docs/DISTROS.md. A distribution must be arm64 and work on the kernel you run; one with a different init system than systemd or procd needs its ~15 services written again.

Repository layout

Path	Contents
install.sh, install.ps1, install.cmd	installers (macOS/Linux, Windows)
uninstall.*	removers
kernel/	kernel build environment, config, patches
upstream/	the mainline kernel port
boot/	initramfs init, boot image builder, slot handling
rootfs/	Ubuntu image and the device services in overlay/
openwrt/	OpenWrt builds and the control panel
arch/	Arch Linux ARM build
android/magisk/	the Magisk module and zip installer
android-vendor/	scripts that copy the needed Android files from your device
tests/	unit tests
tools/	helpers: backup, logs, release tooling
docs/	BUILD, DISTROS, FINDINGS

Licences

Scripts, tools and documentation: MIT. Kernel and the patches in kernel/patches: GPL-2.0. Stock firmware and Android vendor components belong to their owners and are not distributed here.