How to use PREEMPT_RT with kernel 5.4

[Vladimir Kondratiev <vladimir.kondratiev@xxxxxxxxxxxxxxx>]

Hi,

I need to build RT enabled kernel.

With kernels up to and including 5.2, there was fairly easy procedure
for building RT enabled kernel - apply patch, then RT features are
immediately available in "make xxxconfig".

Now, with 5.4. CONFIG_PREEMPT_RT is merged, but it depends_on 
ARCH_SUPPORTS_RT that, in turn, does not set for any architecture.

How should I proceed from here? Am I supposed to just set 
ARCH_SUPPORTS_RT for my architecture? Do I need any other patches to 
start? If yes, where to get it? I see not all patches in the 5.2 bundle 
are merged mainline.

Thanks, Vladimir