How does Ethernet PHY initialized while EMAC booting on AM335x?

Hello.

I would like to boot from EMAC on AM335x.
I am referencing TRM.(tpruh73f.pdf P4288)

I think that Ethernet PHY needs to be initialized before access to network.
But, there is not detail description about sequence of PHY initialization.
(TRM describes that the device support MII, RMII, RGMII PHY.)

Could you let me know..

 - What is the requirement to choose Ethenet PHY?
     (Is it only spec of MII, RMII, RGMII? all maker, all parts are supported?)

 - How does the Ethernet PHY be initialized ?
   I think RBL read PHY information and initialize parameter like NAND boot.
   Is it correct?

Best regards,
RY