The robustness of Linux is widely acknowledged, but it can’t quite match the microsecond management of a real-time operating system (RTOS) for time critical situations such as CNC machine instructions, vehicular control, or health sensor collection. If your software must record, manage, or control events within a narrow and precise time window and you’re invested in Linux for core development, you can consider some of these strategies for handling time-critical tasks without abandoning your familiar environment.
That’s why many modern SoCs have a smaller core for realtime in addition to larger application processors. TI Sitara (Beaglebone) has 2 fast custom arch coprocessors for IO with access to most pins and the ability to DMA into the AP’s address space. All Raspberry Pis up through Pi4 run a proprietary ThreadX runtime on a graphics processor (VPU) to handle bootstrapping the ARM APs, housekeeping, and a large part of the IO.
K. Cool.
But how does this answer OPs questions?