Hello, If I'm understanding this correctly, you are unable to get Coreboot/TianoCore to correctly load/boot efi grub2 (on disk). If this isn't working your not even able to get to chainloading Clover. (Unless grub2 is working, but booting Ubuntu isn't?).
You could either try to get your Coreboot/TianoCore working, or, as you mentioned you could try using Coreboot/SeaBIOS/Duet(Tianocore). Doesn't Clover already include using Duet as an option (to boot from mbr/non-uefi)? If you can get the original bios to boot only in legacy you could see if you can get a working Duet or mbr boot Clover setup working and then try to boot it with Coreboot/SeaBIOS. Some uefi bios's won't boot into legacy mode if they see a gpt disk or a ESP partition though. You should even be able to install a mbr boot block for grub2 from Ubuntu while otherwise keeping the efi grub installed (I think the full auto-install grub2 packages conflict though). Branden -- coreboot mailing list: [email protected] https://mail.coreboot.org/mailman/listinfo/coreboot
