Useful links for RT patching the kernel:
- https://wiki.linuxfoundation.org/realtime/documentation/known_limitations
- https://www.raspberrypi.com/documentation/computers/linux_kernel.html
Tested on kernel 6.1.77 and Raspberry OS Bookworm (link to exact version).
The linux/ contains a submodule with the kernel code already patched (even if it's quite easy to do yourself). You can pull the contents by cloning with --recurse-submodules --shallow-submodules (second option is there to avoid pulling the full kernel repo, which is big).
Cross compile the kernel following the indications in the second link. Remember to configure full real-time capabilities with menu_config before compilation.
Transfer linux folder as follows:
rsync -avuzh -e ssh linux/ alle@rpi0:rtpi/linux/Remember to append dwc_otg.fiq_enable=0 dwc_otg.fiq_fsm_enable=0 to /boot/cmdline.txt
Run the install.sh script.