HI All,
coreboot is a modular design with hardware initialization stage followed by a payload to boot OS https://doc.coreboot.org/payloads.html
There is a new initiative to standardize the bootloader to payload interface. The initiative is called Universal Payload project and details can be found @ https://github.com/universalpayload/Introduction
The goal for this initiative is interoperability between bootloaders and payloads so that different bootloaders can work with different payloads.
An early draft of the spec can be found @ https://universalpayload.github.io/documentation/spec/spec.html.
The Universal Payload community welcomes feedback and contributions.
We are developing various POC codes to demonstrate the concept. One POC uses coreboot as the bootloader and EDKII UEFI as the payload https://github.com/universalpayload/coreboot/tree/universal_payload
Thanks, Subrata