Patching a kernel on RPi

Hi,

I am trying to work on a Raspberry Pi with FreeBSD for the first time.

One thing I need it enabling interrupts on GPIO. I have found the patch
to applied, but I am not fully sure how to recompile the kernel and
install the new kernel on RPi.

I understand that the disk/boot organisation is not really the same as
with another arcitecture and would prefer to not do something that would
make the system unbootable.

TIA,

Olivier
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