Hello, all. I've been successfully using SeaBIOS as secondary bootloader. In more details I have GRUB2-as-payload in flash together with coreboot. SeaBIOS binary is on the HDD and loaded by GRUB when needed. This has an unfortunate consequence that I have to keep vga oprom in flash even if usually I boot without it. The following series of patches make bios.bin.raw multiboot executable with files passed as modules. Example: