Is there any RTOS that supports Cortex-A55?

Hello, I'm studying RTOS nowadays and I want to run RTOS on Cortex-A55 board.

But it seems that there is no RTOS that supports A55.I wonder if I misunderstood.

So, my questions are

1. Is there any RTOS supports Cortex-A55?

2. If not, is there a RTOS with any plans for A55?

I'd appreciate it if anybody answer.