The P2020 is equipped with e500v2 cores, the core provides 36-bit addressing, i.e. can address 64GB of memory space. So 4GB of DDR is not a problem.
I would add that the MMU (Memory Management Unit) is responsible for translation of 32-bit accesses to 36-bit address space. Details can be found in the e500 reference manual, see section 12:
https://www.nxp.com/docs/en/reference-manual/E500CORERM.pdf
Regards,
Bulat