bedrock[RTOS] — Solid Foundation

Philosophy

Three core principles that guide every design decision

∅

Zero Dynamic Allocation

The kernel never calls malloc. All objects — tasks, semaphores, mutexes, queues — come from statically-sized pools determined at compile time. Predictable, no fragmentation.

⏱

Tickless by Design

No periodic timer interrupts. The kernel programs one-shot hardware alarms only when needed, minimizing power consumption and interrupt overhead.

⊞

Clean Separation

Hardware details are strictly isolated in /arch and /boards. The kernel source has zero platform-specific code. Adding a new architecture requires zero kernel changes.

Technical Specs

Key characteristics at a glance

Feature	Details
Language	Pure C (C11/C17)
Time	64-bit microseconds (`br_time_t = uint64_t`), ~584,000 years range
Scheduler	Priority-based preemptive + round-robin at equal priority
Max tasks	Configurable via `CONFIG_MAX_TASKS` (default 16)
Priorities	Configurable via `CONFIG_NUM_PRIORITIES` (default 8)
IPC	Semaphores, Mutexes (priority inheritance), Message Queues
Memory	Zero malloc in kernel; static pools only
Timer	Tickless — one-shot alarms via HAL

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. See Porting Guide for the full HAL specification.

Quick Start

Get up and running in minutes

1

Prerequisites

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

2

Clone & Build

git clone --recurse-submodules https://github.com/bedrockRTOS/bedrock-core
cd bedrock-core
chorus

3

Run on QEMU

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

4

Configuration

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

chorus clean

For detailed build options and platform-specific setup, see the Building guide.

Multi-License Model

Per-directory licensing to maximize flexibility

Directory	License	What it means
`/kernel, /arch, /boards, /include`	BSD 3-Clause	Use freely in any project
`/lib`	LGPL 2.1	Link freely, share modifications to lib itself
`/examples`	GPL 3.0	Reference templates, replace with your own code
`/docs`	CC BY-SA 4.0	Share and adapt with attribution