As we approach the end of 2023, sadly, the real-time kernel " PREEMPT_RT " support still hasn't been mainlined... The main blocker pending is still the ongoing work around non-blocking consoles / threaded console handling to then allow the few dozen remaining out-of-tree RT kernel patches to be merged. The good news is that when the PREEMPT_RT support is ready for mainline, it looks like the RISC-V architecture support will also be real-time friendly too.

Currently the Linux RT patch-set allows enabling PREEMPT_RT for ARM64 (AArch64), ARM, PowerPC, and x86/x86_64 architectures. A set of patches being worked on recently will extend that for RISC-V support too.

As of this month it's now down to 3 patches left for allowing PREEMPT_RT on RISC-V atop the common linux-rt patches. So for those after RISC-V real-time kernel capabilities, by the time the remaining RT patches are finally mainlined, RISC-V should be ready too for being a supported CPU architecture.