Build Environment¶

This environment is for developers who want to rebuild the RTL8196E Linux system or EFR32 radio firmware from source.

Installing pre-built firmware does not require this toolchain. Follow the first-install guide for the much smaller host-package set. The complete environment below takes about 45 minutes and several gigabytes.

Choose a build method¶

	Native Ubuntu / WSL2	Docker
Best for	Regular development, fastest I/O	Reproducible isolated setup
Host	Ubuntu 22.04 or Ubuntu 22.04 under WSL2	Any x86_64 Docker host (see below)
Setup time	About 45 minutes	About 45 minutes
Disk use	About 4 GB in the project	About 8 GB Docker image
Output ownership	Normal project user	Bind-mounted project files

For Windows development, native Ubuntu 22.04 under WSL2 is normally faster and simpler than Docker Desktop. For occasional or CI builds, Docker provides the more reproducible boundary.

Architecture: what actually pins the EFR32 half to x86_64¶

Silicon Labs publishes its tools for several platforms — Commander and slc-cli both have macOS archives, and the Linux Commander download contains aarch64 and aarch32 builds beside the x86_64 one. The constraint here is narrower than "Silabs is x86-only", and worth stating precisely.

Component	Linux x86_64	Linux aarch64	Note
ARM GCC 12.2	yes	yes	`install_silabs.sh` already interpolates `uname -m` into the download URL
Simplicity Commander	yes	yes	`Commander_linux_aarch64_*.tar.bz` ships inside the same `SimplicityCommander-Linux.zip` we download
`slc-cli`	yes	no	it bundles its own CPython 3.10, built for x86_64
Gecko SDK	—	—	source, architecture-neutral

So on an arm64 Linux host slc-cli is the one real blocker for building EFR32 firmware. Two caveats sit next to it. install_silabs.sh extracts Commander_linux_x86_64_* by name, so it would take the wrong build on arm64 even though the right one is in the archive it just downloaded. And its architecture guard accepts aarch64, which lets that host start an install it cannot finish.

Note also that Commander carries a 32-bit x86 helper, commander/resources/cct_linux — that is why install_deps.sh and the Dockerfile enable the i386 architecture, and why running the x86_64 build under emulation on Apple Silicon does not help: Docker Desktop's x86 translation does not cover 32-bit binaries.

The RTL8196E half carries no architecture constraint at all, because nothing prebuilt for the host is shipped: the Lexra toolchain is built from source by crosstool-NG and the Realtek image tools are compiled by the build scripts. An arm64 Linux host therefore builds the complete gateway system — bootloader, kernel, rootfs, userdata — and can flash the radio too, since flash_efr32.sh drives a Python virtualenv (universal-silabs-flasher) rather than Commander, and the EFR32 firmware images are committed pre-built under 2-Zigbee-Radio-Silabs-EFR32/*/firmware/.

For a macOS host, all of this runs in a Linux virtual machine, natively on an Intel Mac. Silicon Labs' own macOS tools exist and can be used directly for EFR32 work, but they are outside these build scripts, and they do not help with the RTL8196E half: that one requires Linux whatever the architecture, because the userdata image is built with mkfs.jffs2. Flashing a gateway from a VM needs its network adapter in bridged mode; see the upgrade guide.

Native setup¶

git clone https://github.com/jnilo1/rtl8196e-gateway.git
cd rtl8196e-gateway/1-Build-Environment
sudo ./install_deps.sh

The script:

installs Ubuntu host packages and i386 compatibility libraries;
builds the patched Lexra MIPS toolchain;
builds the Realtek image tools;
downloads ARM GCC, slc-cli, Gecko SDK 4.5.0, and Commander;
writes the tools under the project directory where build scripts discover them automatically.

Created directories:

<project>/x-tools/mips-lexra-linux-musl/
<project>/silabs-tools/
<project>/1-Build-Environment/11-realtek-tools/bin/

The installer must be invoked with sudo; it runs per-user build steps as the invoking user so the generated trees retain useful ownership.

Docker setup¶

From 1-Build-Environment:

docker build -t rtl8196e-gateway-builder .

Open an interactive build shell:

docker run -it --rm \
  -v "$(pwd)/..:/workspace" \
  rtl8196e-gateway-builder

Or run a complete build directly:

# RTL8196E side
docker run --rm \
  -v "$(pwd)/..:/workspace" \
  rtl8196e-gateway-builder \
  /workspace/3-Main-SoC-Realtek-RTL8196E/build_rtl8196e.sh

# EFR32 side
docker run --rm \
  -v "$(pwd)/..:/workspace" \
  rtl8196e-gateway-builder \
  /workspace/2-Zigbee-Radio-Silabs-EFR32/build_efr32.sh

The bind mount is bidirectional, so built images appear in the normal project directories. The container entrypoint links its internal toolchains into the same /workspace/x-tools and /workspace/silabs-tools locations expected by native build scripts.

If you still have the pre-v4 image name, retag it rather than rebuilding:

docker tag lidl-gateway-builder rtl8196e-gateway-builder

What is installed¶

Tool set	Used by	Version / source	Project location
Lexra MIPS GCC/binutils/musl	Bootloader, kernel, rootfs, userdata	GCC 15.2.0, binutils 2.45.1, musl 1.2.6	`x-tools/mips-lexra-linux-musl/`
Realtek `cvimg`, `lzma`, `flash_erase`	Image packaging and device tools	Built from source	`1-Build-Environment/11-realtek-tools/bin/`
ARM GCC	EFR32 applications	12.2	`silabs-tools/arm-gnu-toolchain/`
Silabs `slc-cli` + Gecko SDK	EFR32 generation/build	SLC 5.11, GSDK 4.5.0	`silabs-tools/slc_cli/`, `silabs-tools/gecko_sdk/`
Simplicity Commander	EFR32 inspection/recovery	Silabs pre-built tool	`silabs-tools/commander/`

The RTL8196E uses a Lexra core without standard MIPS unaligned-access instructions. Do not replace the supplied compiler with a generic mips-linux-gnu-gcc.

EFR32 Series 1 is no longer supported by recent Silabs SDK lines. The on-chip firmware intentionally builds against Gecko SDK 4.5.0; the modern EmberZNet 8.x path moves the stack to host-side zigbeed rather than compiling 8.x for the radio.

Build targets¶

Complete RTL8196E system¶

./3-Main-SoC-Realtek-RTL8196E/build_rtl8196e.sh
BOARD=sengled-e39-g8c ./3-Main-SoC-Realtek-RTL8196E/build_rtl8196e.sh
KERNEL=7.2 ./3-Main-SoC-Realtek-RTL8196E/build_rtl8196e.sh

Reference: RTL8196E Linux system.

EFR32 firmware¶

./2-Zigbee-Radio-Silabs-EFR32/build_efr32.sh
./2-Zigbee-Radio-Silabs-EFR32/build_efr32.sh ncp rcp
BOARD=sengled-e39-g8c ./2-Zigbee-Radio-Silabs-EFR32/build_efr32.sh ncp

Reference: EFR32 radio firmware.

Each top-level builder supports targeted work; run it with --help before assuming a target name or environment variable.

Directory map¶

Path	Purpose
`10-lexra-toolchain/`	crosstool-ng configuration and Lexra compiler patches
`10-lexra-toolchain/TOOLCHAIN_UPDATE.md`	Toolchain version history and bump procedure
`11-realtek-tools/`	`cvimg`, legacy LZMA, and device-side flash utilities
`12-silabs-toolchain/`	Silabs tool download and environment setup
`Dockerfile`	Reproducible Ubuntu 22.04 environment
`install_deps.sh`	Native installation orchestrator

Troubleshooting¶

Downloads or Docker build fail¶

Toolchain setup downloads several upstream archives and can fail transiently. Retry the same command first. For a deliberately clean Docker retry:

docker build --no-cache -t rtl8196e-gateway-builder .

`slc-cli` or Gecko SDK is missing¶

Confirm silabs-tools/env.sh exists and that the SDK download completed. Source it for manual tool use:

. ./silabs-tools/env.sh

Normal EFR32 build scripts source it automatically.

Toolchain not found¶

Keep the generated directories at their default project-relative locations or put the compiler explicitly on PATH. An error that a valid MIPS binary cannot execute may indicate missing i386 compatibility libraries rather than a missing file.

Git LFS content is incomplete¶

The Gecko SDK needs Git LFS. Verify git lfs version, then fetch the missing objects in the relevant checkout. Both supported setup methods install Git LFS.