As long as only the BIOS partition is being flashed without the VGA blob, the stock BIOS back up is not required to compile.
Build the latest merged into the master git branch:
./build.sh --bleeding-edge x230
Latest stable release:
./build.sh x230
coreboot_lenovo-x230-complete.rom - The complete Coreboot ROM is the 12MB version used for internal flashing.
coreboot_lenovo-x230-complete.rom.sha256 - sha256 checksum of 12MB Coreboot Rom
NOTE: As this is compiled without the stock BIOS, all IFD, GBE and ME blobs are stubs. Use the flash.sh script at the root of the directory.
coreboot_lenovo-x230-top.rom - The 4MB Coreboot BIOS that can be flashed externally onto the top BIOS chip.
coreboot_lenovo-x230-top.rom.sha256 - sha256 checksum of 4MB Coreboot BIOS
NOTE: See Skulls for instructions on how to flash the top BIOS chip as well as unlocking the IFD and cleaning Intel ME