Smol Kernel for ARMv7

Developed and tested on NanoPi Neo v1.4

Building and running

System requirements

cargo, xargo, a gcc toolchain for armv7 (arm-none-eabihf-gcc or equivalent), a Rust toolchain for armv7 installed (armv7a-none-eabihf or equivalent)

Running the kernel

Use the ./build.sh script to automatically build all the necessary components. Then copy boot.scr and smol.bin to the root of the SD card.

Building the executable

Run

xargo build -Z build-std --release --target armv7a-none-eabihf

followed by

arm-none-eabi-gcc -T linker.ld -o out/smol.elf -ffreestanding -O2 -nostdlib boot.o ../target/armv7a-none-eabihf/release/libkernel.rlib ../target/armv7a-none-eabihf/release/deps/*.rlib

to build and link the executable.

Copy smol.elf file to the sd-card and use u-boot to load and run it.

Running the executable

U-boot commands example on NanoPi Neo (may be the same for other boards):

fatload mmc 0 0x42000000 smol.elf

go 0x42000000

Then connect the device using serial UART console with 115200 8N1 (no hardware flow control!) settings.

Currently implemented

• Basic register support (UART initialization)
• GPIO support
• RTC support
• Basic Heap Allocator using linked-list-allocator