Here’s a step-by-step guide to help you build a minimal, fast-booting Linux system that meets your specified key requirements. This guide assumes you’re targeting an ARM SoC (like Allwinner) with Lima GPU and aiming for custom kernel and userspace.
⚙️ Step 1: Set Up the Build Environment
Install required packages on your host Linux (Ubuntu/Debian-based):
sudo apt update && sudo apt install -y \
build-essential gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf \
u-boot-tools debootstrap qemu-user-static \
libncurses-dev bc bison flex libssl-dev
🧱 Step 2: Download and Prepare Kernel Source
git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
cd linux
- Checkout the latest LTS kernel version supported by Lima.
- Apply board/device-specific patches if needed.
🔧 Step 3: Configure and Strip the Kernel
Start configuration:
make ARCH=arm menuconfig
Minimal Kernel Config Options:
- ✅ Enable DRM/KMS & Lima (
CONFIG_DRM,CONFIG_DRM_LIMA) - ✅ Enable HDMI and audio (
CONFIG_SND_SOC,CONFIG_HDMI) - ✅ Enable Input Devices: Keyboard, Mouse, Gamepad (
CONFIG_INPUT_KEYBOARD,CONFIG_INPUT_MOUSE,CONFIG_INPUT_JOYSTICK) - ✅ Filesystems: Only enable needed ones like ext4 or squashfs
- ❌ Disable: WiFi, Bluetooth, IPv6, VPN, Debugging, ACLs, Hibernation, Virtualization, etc.
- ✅ Enable static binary support if needed (
CONFIG_STATIC_LINK) - ✅ Disable kernel debugging (
CONFIG_DEBUG_KERNEL=n)
Then compile:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- zImage dtbs -j$(nproc)
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- modules
🧰 Step 4: Build Minimal Root Filesystem
Use debootstrap or buildroot:
Option 1: debootstrap
sudo debootstrap --arch=armhf --foreign stable ./rootfs http://deb.debian.org/debian
sudo cp /usr/bin/qemu-arm-static ./rootfs/usr/bin/
sudo chroot ./rootfs /debootstrap/debootstrap --second-stage
Strip unnecessary packages:
chroot ./rootfs
apt remove --purge -y systemd network-manager wpasupplicant \
isc-dhcp* avahi-daemon openssh-server \
&& apt autoremove -y && apt clean
exit
Option 2: buildroot (recommended for static and minimal)
git clone https://github.com/buildroot/buildroot.git
cd buildroot
make menuconfig
Enable:
- Toolchain: external or internal static toolchain
- Target packages: GCC (build essentials), SDL2, minimal init
- Remove all networking and debugging services
🧱 Step 5: Static Build of SDL2 and User Binaries
Compile SDL2 statically:
./configure --enable-static --disable-shared
make && make install
Cross-compile your own app statically:
arm-linux-gnueabihf-gcc -static -o myapp myapp.c `sdl2-config --cflags --libs`
🚀 Step 6: Optimize Boot Time
- Use
init=/sbin/init(simple custom init or busybox). - Remove all unnecessary services.
- Use squashfs or initramfs.
- Use U-Boot for fast boot and directly launch kernel.
- Optionally use
systemd-analyze blame(if using systemd) or bootchart to find slow areas.
💾 Step 7: Assemble Image
Use your preferred method to combine:
zImagedtb- RootFS (as ext4, squashfs, or initramfs)
Example for SD card:
dd if=u-boot-sunxi-with-spl.bin of=/dev/sdX bs=1024 seek=8
Copy kernel and rootfs to partitions.
✅ Step 8: Test on Hardware
Boot on target device via SD card or eMMC. Confirm:
- HDMI output
- Input devices working
- Your SDL2 app launches
- Fast boot time (target < 5 seconds)
📌 Summary
| Component | Optimized For |
|---|---|
| Kernel | Minimal, GPU, HDMI |
| Init System | Static / BusyBox |
| RootFS | Custom, stripped |
| Build Method | Cross-compiled |
| SDL2 & App | Statically linked |
| Boot Time | Under 5 seconds |
