Upstream coreboot on Intel Haswell Chromebook

Disable write protection by following the Chromium OS wiki 

  1. Open device
  2. Remove write protect screw
  3. Boot device in developer mode
  4. Disable flash write protection
flashrom --wp-disable

Check out coreboot

git clone
cd coreboot

Extract BIOS from running system

The BIOS from the running system will contain some specific data in GBB and VPD regions that are unique.  It is recommended to extract and save this BIOS in case you want to restore to previous unique device information.  Without a valid HWID the system will be unable to recover or receive updates.

flashrom -r device_bios.bin

Extract BIOS from Firmware Update utility on the device

The BIOS extracted from a running system does not contain the Management Engine firmware as that region is not readable from the host.  The firmware update utility contains a raw BIOS update image which will contain the Management Engine binary.

Copy /usr/sbin/chromeos-firwmwareupdate from device, execute, and copy bios.bin to coreboot root.

chromeos-firwmareupdate --sb_extract /tmp
cp /tmp/bios.bin .

Extract SPI Descriptor and Management Engine binary

ifdtool -x bios.bin

Extract MRC binary

cbfstool bios.bin extract -n mrc.bin -f mrc.bin

Extract VBIOS binary

Save as PCI Device ID 0x0a06 to make SeaBIOS happy

cbfstool bios.bin extract -n pci8086,0406.rom -f pci8086,0a06.rom

Configure Coreboot

make menuconfig

Suggested Settings

> Mainboard -> Mainboard Vendor -> Google
> Mainboard -> Mainboard Model -> Falco
> Chipset -> Add a System Agent binary -> mrc.bin
> VGA BIOS -> Add a VGA BIOS image -> pci8086,0a06.rom
> VGA BIOS -> VGA device PCI IDs -> 8086,0a06
> Console -> Serial port console output -> DISABLE
> Payload -> Add a payload -> SeaBIOS
> Payload -> SeaBIOS version -> master
> ChromeOS -> Build for ChromeOS -> DISABLE

Build Coreboot and SeaBIOS


Configure SeaBIOS to use ESC key instead of F12

echo -ne "\x01" > boot-menu-key
echo -e "\nPress ESC for boot menu.\n" > boot-menu-message
cbfstool build/coreboot.rom add -f boot-menu-key -n etc/boot-menu-key -t raw
cbfstool build/coreboot.rom add -f boot-menu-message -n etc/boot-menu-message -t raw

If setting a boot splash screen:

cbfstool build/coreboot.rom add -f bootsplash.jpg -n bootsplash.jpg -t raw

Add SPI Descriptor

dd if=flashregion_0_flashdescriptor.bin of=build/coreboot.rom conv=notrunc

Add Management Engine

ifdtool -i me:flashregion_2_intel_me.bin build/coreboot.rom
mv build/ build/coreboot.rom