coreboot version 4.13 rom for thinkpad t400 featuring seabios v. 1.14.0 https://seabios.org/Releases#SeaBIOS_1.14.0
commit 5c186c6777c9438ff4681929c9c25c98dee28bef
now it has been compiled to use libgfixnit graphics initialization with resolution 1280x800
gbe.bin has been added with a random MAC address 00:11:22:33:44:55
No support to intel wifi and bluetooth
./cbfstool t400m4rc0.rom add-int -i 1000 -n etc/boot-menu-wait has been already applied to reduce the waiting time
added flashregion_0_flashdescriptor.bin from libreboot
ich9fdgbe_8m.bin with 00:11:22:33:44:55 mac address
No secondary payloads added
capable to boot any linux, bsd and windows
You can add added a bootspash image (the ones in the repo are already set to be used with coreboot, colours will be fine) ./cbfstool t400m4rc0.rom add -f (file).jpg -n bootsplash.jpg -t raw
To see how this (or my others built images) works, just have a look into my youtube https://www.youtube.com/user/marcolinoxz