This is realtime, microkernel operating system with fully static operation currently targeted towards Cortex-M microcontrollers having usable support for MPU. Currently microcontrollers based on Cortex-M0+, Cortex-M3, Cortex-M4 and Cortex-M7 are known to be supported.
This operating system provides only several basic services needed to make things happen:
- memory protection and isolation of processes
- multi-threaded, multi-process scheduler
Additionally CMRX offers basic set of IPC features:
- support for fast userspace mutexes
- thread management: on demand creating, disposing and joining of other threads
- signal delivery: threads can register signal handlers and other threads can send them signals
- remote procedure call: kernel can dispatch call performed using interface and method ID and then provide result back to the caller.
In line with microkernel architecture, operating system itself does not offer any non-essential services. Instead of this, there is a mechanism, which allows implementation of various services and system calls using standalone processes, which are isolated from the rest of system.
CMRX does not offer any specific set of higher RTOS API. The only API (optional) CMRX offers is POSIX-compatible threading and signal API. Absence of any specific RTOS API is intentional. No defined higher API means, that on top of CMRX kernel, any API can be implemented, be it CMSIS-RTOS or OSEK OS.