By @unix_byte
QNX Neutrino RTOS is a microkernel real-time operating system in which the kernel itself is deliberately kept extremely small. In QNX, only the most fundamental mechanisms run in kernel mode: scheduling, inter-process communication (IPC), interrupt handling, and basic memory management. All other operating-system functionality, including device drivers, filesystems, networking stacks, and system services, executes in user space as isolated services, communicating with the kernel and with each other via message passing.
The microkernel architecture provides two advantages: extreme fault isolation and high availability. Because drivers and stacks run in protected memory as standard user processes, a software failure in a single component (such as a Wi-Fi driver) cannot "panic" the kernel or crash the entire system. Instead, the failed service can be terminated and restarted dynamically without a reboot. Furthermore, the use of priority-driven preemptive scheduling ensures that high-priority tasks always meet their deadlines, making it a "hard" real-time system suitable for mission-critical environments like automotive safety systems and medical robotics.
QNX has been certified up to ASIL-D (which includes ASIL-B), as an operating system kernel and its core OS services. ASIL (Automotive Safety Integrity Level) is a risk classification system used to define the safety requirements for vehicle components.
- ASIL-B is typically applied to systems where a failure might result in moderate risk or injuries (such as instrument clusters or rear-view cameras).
- ASIL-D represents the highest level of automotive hazard and requires the most stringent safety measures. It is reserved for life-critical systems where a malfunction could lead to fatal accidents, such as electronic braking, steering, or airbag deployment.
Linux cannot do this—its massive code base and monolithic kernel make the formal ASIL-D certification practically infeasible. Recently, Red Hat has achieved ASIL-B certification for a controlled instance of the Linux math library (libm)—a component of glibc, which itself is only one subsystem of the Linux userspace. Achieving an OS-level certification comparable to QNX would require a Linux system to include the kernel, device drivers, firmware, and configurations where each element subject to verification, traceability, impact analysis, and long-term configuration control.
