Choosing the Right Software Foundation for Your Device: From Bare Metal to Embedded Linux

Choosing between bare metal, RTOS, or embedded Linux isn’t just a technical decision—it’s a strategic one. It impacts development time, system scalability, cost, and long-term maintainability. 

This post breaks down the core differences, trade-offs, and use cases of each to help embedded developers and engineering teams make the right choice from the start. 

Bare Metal: The minimalist’s choice 

Bare-metal programming refers to writing software that directly interacts with the hardware—no operating system, no abstraction. This means working with device registers, managing peripheral clocks, and implementing everything from scratch, including scheduling and memory management. 

Best for: 

• Ultra-simple devices (LED control, sensor polling, power management) 

• Time-critical loops with minimal overhead 

• Resource-constrained MCUs (8-bit, 16-bit, or low-power 32-bit) 

Pros: 

• Deterministic execution with zero OS overhead 

• Minimal binary size and boot time 

• No licensing or runtime dependencies 

Cons: 

• No true multitasking or context switching 

• No memory protection; harder to debug and scale 

• Increased development time as system complexity grows 

Note: Many features like GUI (e.g. LVGL), networking, TLS, OTA, and secure boot are possible on bare metal, but require custom integration and careful design. These are not OS-exclusive capabilities.

Typical Scenario: You’re building a device with tight timing constraints (e.g., sensor reads every 10µs) and minimal external interfaces. You need maximum performance and full hardware control, and you’re comfortable implementing your own scheduler or timer-based loop. 

RTOS: Lightweight Real-Time Scheduling with Modularity 

A Real-Time Operating System (RTOS) like Zephyr or FreeRTOS offers preemptive multitasking, task prioritization, inter-process communication (IPC), and often device driver libraries. It’s ideal for mid-range systems that require structure but not the full overhead of a general-purpose OS. 

Best for: 

• Systems with multiple tasks (sensor fusion, motor control, communication) 

• Applications needing deterministic behavior with more abstraction than bare metal 

• Devices with moderate resources (e.g., Cortex-M4/M7 with 128 KB+ RAM for e.g) 

Pros: 

• Preemptive task scheduling and priority management 

• Real-time guarantees (with fixed time-slicing or static scheduling) 

• Built-in support for queues, semaphores, mutexes, and sometimes file systems 

• Shorter development cycle vs. bare metal for multi-task systems 

Cons: 

• Adds some overhead and complexity compared to bare metal 

• Requires understanding of concurrency pitfalls (deadlocks, priority inversion) 

• Often no MMU support → less robust than full OS in memory isolation 

• Licensing or safety certification can add cost

Note:  OTA is supported in RTOS environments like Zephyr or FreeRTOS (e.g., AWS IoT OTA), but in many other RTOS options, OTA must be implemented manually or using third-party tools. 

 Key Insight: Many embedded projects start with a super loop on bare metal and evolve into ad-hoc schedulers. If you’re managing multiple peripherals, need background tasks (e.g. UART reception), or want predictable timing, it’s often better to use an RTOS from the start. 

Embedded Linux: Scalable OS for Complex, Connected Devices 

Embedded Linux is a full-fledged operating system with virtual memory, user-space processes, drivers, networking, and tools. Often built using Yocto, Buildroot, or vendor SDKs, it provides a rich environment for building advanced devices. 

Best for: 

• Products requiring user interfaces, multimedia, cloud connectivity 

• Devices that need secure OTA updates and long-term support 

• Applications with heavy software stacks and large resource budgets 

Pros: 

• Multi-threading, MMU support, and process isolation 

• Vast ecosystem (TCP/IP stacks, SSL, USB, Wi-Fi, Bluetooth, etc.) 

• Open-source drivers and middleware (camera, audio, GPU) 

• Yocto/Buildroot enable fully custom and reproducible OS builds 

Cons: 

• Requires more powerful hardware (typically Cortex-A, 256MB+ RAM) 

• Non-deterministic by default (Linux is not a real-time OS unless patched) 

• Steep learning curve (bootloader, device trees, init systems) 

• Security and update infrastructure must be designed and maintained

Note: Sub-millisecond real-time performance is achievable on Linux, even without PREEMPT_RT, using techniques like CPU isolation, IRQ affinity, and careful tuning. 

Real-World Fit: Embedded Linux could be an overkill for turning on relays or reading a sensor. But if you’re building a touchscreen HMI, a networked gateway, or an edge AI device, Linux provides the software architecture and scalability you’ll need.