Raspberry pi4: kernel 64bit with RT extension

Question

I followed these instructions in order to install RT extension for RPI 64bits:

64bit RT Kernel Compilation for Raspberry Pi 4B

The procedure works, I arrived at the end and the new kernel seems activated, but not the RT extension! I selected the version 5.15.31 and now "uname -a" returns:

Linux raspberrypi 5.15.30-rt38-v8+ #1 SMP PREEMPT Mon Mar 28 01:46:41 CEST 2022 aarch64 GNU/Linux

As you can see, it still PREEMPT but not with RT .. What can happened? Can you help me to activate real-time extension?

Thanks Bye Andrea

Answer 1

I found.. the issue was that I built and activated the kernel directly on Raspberry Pi when it works ONLY if done on Linux x86, basically on another PC and then transferred to RPI. I was convinced it was the same but it's not. Strange that finally I got a result without errors basically..

Finally I found a kernel already built here: Kernel Raspberry 5.4.61 64bits

and I followed the suggestions found here: raspberry-pi-4b-preempt-rt-kernel-419y-performance-test

And finally I was able to just install the kernel and see it working or RPI. Hopefully this could help someone else.

Linux raspberrypi 5.4.61-rt37-v8+ #1 SMP PREEMPT_RT Wed Sep 9 18:58:22 CEST 2020 aarch64 GNU/Linux

Bye Andrea