The RT developers do not create patch sets for every kernel version because of the amount of effort involved. On average, they create patches for every other kernel. The most recent kernels that are supported at the time of writing are as follows:
The patches are available at https://www.kernel.org/pub/linux/kernel/projects/rt.
If you are using the Yocto Project, there is an
rt version of the kernel already. Otherwise, it is possible that the place you got your kernel from already has the
PREEMPT_RT patch applied. Otherwise, you will have to apply the patch yourself. Firstly, make sure that the
PREEMPT_RT patch version and your kernel version match exactly, otherwise you will ...