BootROM for A78

Hi,

I am planning to boot ARM A-78 core with Linux.
I have gone through some documents and ended up with below understanding of cortex ARM-A78's boot process:

ARM A-78 Core Reset => BootROM => 1st stage BootLoader => 2nd stage BootLoader => Kernel Image

Is my understanding correct or I have missed something ?

If this is the case, can any one help me for BootROM code ?
Like,

- from where to get the source code of BootROM ?
- How to develop one by our self ?

If this isn't the case, please help me understand it better.

Thanks You,
Maunik Patel