bedrock[RTOS]

Solid Foundation — A nanokernel real-time operating system written in pure C (C11/C17).

When the foundation is solid, you're free to create.

Philosophy

bedrock[RTOS] is designed around three core principles:

1. Zero dynamic allocation — The kernel never calls malloc. All objects (tasks, semaphores, mutexes, queues) come from statically-sized pools determined at compile time.
2. Tickless by design — No periodic timer interrupts. The kernel programs one-shot hardware alarms only when needed, minimizing power consumption and interrupt overhead.
3. Clean separation — Hardware details are strictly isolated in /arch and /boards. The kernel source code has zero platform-specific code. Adding a new architecture requires zero kernel changes.

HAL Interface

The kernel accesses hardware exclusively through three timer functions:

void      br_hal_timer_init(void);
br_time_t br_hal_timer_get_us(void);
void      br_hal_timer_set_alarm(br_time_t abs_us);

Plus interrupt control and context switch primitives defined in include/bedrock/br_hal.h.

Quick Start

Prerequisites

• arm-none-eabi-gcc toolchain
• qemu-system-arm (for Cortex-M3 emulation)
• chorus build system (included as 3rd/tools/chorus)

Build

chorus

Run on QEMU

qemu-system-arm -M lm3s6965evb -nographic -kernel bedrock_example.elf

Clean

chorus clean

Configuration

Edit Kconfig values or pass them as -D flags in chorus.build CFLAGS.

Multi-License Model

bedrock[RTOS] uses a per-directory licensing approach to maximize flexibility:

• /kernel, /arch, /boards, /include — GNU GPL 3.0 (Runtime exception)
• /lib — GNU GPL 3.0 (Runtime exception)
• /examples — GNU GPL 3.0 (Runtime exception)
• /docs — CC BY-SA 4.0