SyterKit

A bare-metal firmware framework and bootloader toolkit for Allwinner SoCs

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Overview

SyterKit is a small, static bare-metal firmware framework for Allwinner SoCs. It provides board bring-up, peripheral drivers, image loading, bootloader applications, and standalone firmware utilities for both ARM and RISC-V platforms.

SyterKit uses GNU Make, Kconfig, Kbuild-style object lists, application-owned initialization, and Linux-style board device trees compiled to immutable C data by dt2c.

Supported Boards

Run make list-defconfigs for the authoritative list in your checkout. Board-specific applications and hardware notes live in boards/. Archived board sources are preserved under archive/.

Board	SoC / Platform	SyterKit CPU	Configuration
TinyVision	V851se/V851s3	1 × Cortex-A7	tinyvision_defconfig
LonganPi 3H	H618	4 × Cortex-A53	longanpi-3h_defconfig
Avaota A1	T527/A527	8 × Cortex-A55	avaota-a1_defconfig
Radxa Cubie A7A	A733	6 × Cortex-A55 + 2 × Cortex-A76	radxa-cubie-a7a_defconfig
Avaota F1	V821	Xuantie E907 + Andes A27L2	avaota-f1_defconfig
Avaota F2	V861	Xuantie E907 + 2 × Xuantie C907	avaota-f2_defconfig
Avaota M1	A537	6 × Cortex-A53 + 2 × Cortex-A73	avaota-m1_defconfig
YuzukiNeko	F101	Xuantie C907	yuzukineko_rv32_defconfig, yuzukineko_rv32_usb_defconfig, yuzukineko_rv64_defconfig
TLT153 MiniEVM	T153	4 × Cortex-A7	tlt153-minievm_defconfig
TLT536 EVM	T536	4 × Cortex-A55	tlt536-evm_defconfig

Active configurations are grouped under configs/<board>/. Most boards provide sram_defconfig, efex_defconfig, and dram_defconfig variants; the public Make targets remain flat, e.g. make avaota-a1_efex_defconfig.

Architecture

SyterKit is intentionally small and static. The selected board contributes its applications and DTS, Kconfig selects the architecture and drivers, dt2c turns the board DTS into compile-time data, and the linker combines the selected objects into the final firmware image.

See Compile-time device tree, Driver architecture, and optional Rust FFI for the full model.

Getting Started

Prerequisites

A Linux host needs GNU Make, a host C compiler, Flex, Bison, pkg-config, ncurses development headers, and a bare-metal cross compiler. On Ubuntu (ARM32 targets):

sudo apt-get update
sudo apt-get install -y build-essential gcc-arm-none-eabi flex bison \
	libncurses-dev pkg-config doxygen graphviz default-jre

RISC-V boards require a compatible RISC-V toolchain whose flags match the CPU selected by Kconfig.

The checked-in Linux x86_64 dt2c distribution (tools/bin/dt2c) includes a musl-static binary and matching headers, so neither Rust nor the submodule is needed for a normal build. Initialize the submodule only to develop dt2c itself:

git submodule update --init tools/dt2c

An external dt2c installation can be selected instead:

make DT2C=/opt/dt2c/dt2c DT2C_INCLUDE=/opt/dt2c/include ...

Configure and Build

List the available boards, select one, and build:

make list-defconfigs
make tinyvision_defconfig
make -j$(nproc)

Out-of-tree builds follow the Linux kernel O= convention:

make O=out tinyvision_defconfig
make O=out -j$(nproc)

Useful targets:

Target	Description
make menuconfig	Edit the active configuration interactively
make list-apps	List applications selected for the active board
make syter_boot	Build a single application and its three images
make firmware	Build board companion firmware, when declared
make utilities	Build the standalone BL33 utilities
make artifacts	Build images, companion firmware, and utilities
make test	Run host and QEMU tests
make docs	Generate the Doxygen API documentation
make check	Make/Kconfig source-tree consistency checks

Override the toolchain prefix when it is not in the default location:

make CROSS_COMPILE=/opt/toolchains/arm-none-eabi- -j$(nproc)

Build Outputs

Each application is written below build/<board>/<application>/ (or the chosen O= directory):

File	Purpose
<app>_fel.bin	Load and run from SRAM with a host FEL tool
<app>_card.bin	Padded and checksummed for SD/eMMC boot
<app>_spi.bin	Padded and checksummed for SPI NOR/NAND boot
<app>_fel.elf, <app>_bin.elf	Symbols and debugging
<app>_fel.map, <app>_bin.map	Link maps

Writing Boot Media

Warning: Writing raw devices can destroy existing data. Confirm the target device before running any command.

SD/eMMC, MBR-formatted media (BROM searches at an 8 KiB offset):

sudo dd if=syter_boot_card.bin of=/dev/sdX bs=1024 seek=8 conv=fsync

SD/eMMC, GPT media (secondary 128 KiB BROM location):

sudo dd if=syter_boot_card.bin of=/dev/sdX bs=1024 seek=128 conv=fsync

SPI NAND/NOR (redundant copies at 64 KiB intervals, programmed with xfel):

dd if=syter_boot_spi.bin of=spi.img bs=2k
dd if=syter_boot_spi.bin of=spi.img bs=2k seek=32
dd if=syter_boot_spi.bin of=spi.img bs=2k seek=64

xfel spinand write 0 spi.img   # or: xfel spinor write 0 spi.img

Detailed boot-header and media-layout documentation is available in the documentation source.

Documentation

• Getting started and Allwinner boot flow
• Driver architecture
• Compile-time device tree
• Bare-metal Rust FFI
• Generated API documentation

Contributing

Contributions are welcome! To contribute:

1. Fork the repository and create a feature branch.
2. Follow the existing code style (.clang-format is provided).
3. Run make check and make test before submitting.
4. Open a pull request with a clear description of the change.

Bug reports and feature requests are tracked in the issue tracker.

Code of Conduct

This project follows the Contributor Covenant Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to the community leaders listed in the document.

License

SyterKit is released under the GNU General Public License v2.0. See LICENSE for the full text.