Add support for a SeaBIOS payload

Allow to optionally add a legacy BIOS (SeaBIOS) in front the usual
payload (U-Boot) to allow booting legacy OS for production purpose.

This is an intermediate solution where SeaBIOS is the primary payload
and can trigger the secondary payload (the usual U-Boot) through its
boot menu. We might want to do the opposite later once we have done the
required development in U-Boot.

TEST=boot FreeDOS and Ubuntu from a USB key on Lumpy

Change-Id: Ibe031bff4fb4e3eda827ac301f90a6b3d2a126fb
Reviewed-by: Simon Glass <>
Commit-Ready: Vincent Palatin <>
Tested-by: Vincent Palatin <>
2 files changed