We have a ppc32 MPC8248 board that is working perfectly with the 4.19
kernel.
We have noticed two issues with the 5.2 kernel:

1) If the new CONFIG_PPC_KUAP (kernel userspace access protection) is
enabled the kernel freezes right after initializing all the drivers and
just before starting /sbin/init.

2) If CONFIG_PPC_KUAP is disabled the system starts up, but any user space
program will hang indefinitely after calling the GCC atomic
"__sync_bool_compare_and_swap".  This happens when nginx starts.  The same
nginx binary works fine on a 4.19 kernel.