rnk is a RTOS targeting ARM architecture.

• Targeting Cortex-M
• Premptive scheduling
• Support static and dynamic application (using custom file format - RFLAT)
• Isolation using MPU and privileged/unprivileged modes
• Device tree support
• POSIX API
• SEGGER SystemView support

• STM32F4 family (actually developed and tested on a STM32F401)
• STM32L4 family (actually developed and tested on a STM32L443)

• arm-none-eabi toolchain (https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads)
• kconfig-frontends (http://ymorin.is-a-geek.org/projects/kconfig-frontends)

• export ARCH=arm
• export your cross compiler bin/ folder in PATH
• export CROSS_COMPILE=arm-none-eabi- or
• edit the cross compiler path in "setup.sh" and use it like: $. setup.sh

then

• make the boards config you wanted (take a look at: arch/arm/configs), for example: make stm32f429_disco_defconfig
• and then: make clean && make
• flash the kernel on the board & enjoy

Build configurations are powered by Kconfig, and can be used by typing: make menuconfig (or nconfig)