I think you're asking about writing "direct to the metal" software on the Pi, which I hope someone will address here. To answer your question indirectly, there

I think you're asking about writing "direct to the metal" software on the Pi, which I hope someone will address here. To answer your question indirectly, there are ways to bend Linux to do realtime like rt-preempt [0] but it doesn't go as far as RTLinux [1], which virtualizes the entire OS to run under a hypervisor that is essentially just a service routine for a hardware nonmaskable interrupt. Linux isn't even aware it's being preempted in this model. It's a beautiful approach, but RTLinux was proprietary and hard to write code for (because, interrupt handler), so it never achieved much traction. [0] https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO [1] https://en.m.wikipedia.org/wiki/RTLinux https://en.m.wikipedia.org/wiki/RTLinux