This page describes how to run coreboot on the ASRock H81M-HDS.

Required proprietary blobs

This board currently requires a proprietary blob in order to initialise the RAM and a few other components. The blob largely consists of Intel's Memory Reference Code (shortened to mrc), and is just under 200 KiB in size. It is also known as a system agent binary. Unfortunately, it is not currently possible to distribute this as part of coreboot. However, the mrc can be obtained from a Haswell Chromebook firmware image, and you might find one online. The mrc from a ChromeOS image can be extracted with the following command. If extracting from a "standard" coreboot image, omit -r RO_SECTION.

cbfstool coreboot.rom extract -f mrc.bin -n mrc.bin -r RO_SECTION

Now, place mrc.bin in the root of the coreboot directory. Alternatively, place it anywhere you want, and set MRC_FILE to its location when building coreboot.

Building coreboot

A fully working image should be possible just by setting your MAC address and obtaining the Haswell mrc. You can set the basic config with the following commands. However, it is strongly advised to use make menuconfig afterwards (or instead), so that you can see all of the settings.

make distclean # Note: this will remove your current config, if it exists.
touch .config
./util/scripts/config --enable VENDOR_ASROCK
./util/scripts/config --enable BOARD_ASROCK_H81M_HDS
./util/scripts/config --enable HAVE_MRC
./util/scripts/config --set-str REALTEK_8168_MACADDRESS "xx:xx:xx:xx:xx:xx" # Fill this in!
make olddefconfig

If you don't plan on using coreboot's serial console to collect logs, you might want to disable it at this point (./util/scripts/config --disable CONSOLE_SERIAL). It should reduce the boot time by several seconds. However, a more flexible method is to change the console log level from within an OS using util/nvramtool, or with the nvramcui payload.

Now, run make to build the coreboot image.

Flashing coreboot

Internal programming

The main SPI flash can be accessed using flashrom. By default, only the BIOS region of the flash is writable. If you wish to change any other region, such as the Management Engine or firmware descriptor, then an external programmer is required (unless you find a clever way around the flash protection).

The following command may be used to flash coreboot:

sudo flashrom -p internal --ifd -i bios --noverify-all -w coreboot.rom

The use of --noverify-all is required since the Management Engine region is not readable even by the host.

External programming

The flash chip is a 4 MiB socketed DIP-8 chip. Specifically, it's a Winbond W25Q32FV, whose datasheet can be found here. The chip is located to the bottom right-hand side of the board. For a precise location, refer to section 1.4 (Motherboard Layout) of the board manual, where the chip is labelled "32Mb BIOS". Take note of the chip's orientation, remove it from its socket, and flash it with an external programmer. For reference, the notch in the chip should be facing towards the bottom of the board.

Known issues

  • PCIe graphics is non-functional. The PCIe 16x slot doesn't work with other devices, either.

  • The VGA port doesn't work until the OS reinitialises the display.

  • There is no automatic, OS-independent fan control. This is because the super I/O hardware monitor can only obtain valid CPU temperature readings from the PECI agent, but the required driver doesn't exist in coreboot. The coretemp driver can still be used for accurate CPU temperature readings from an OS.


  • parallel port
  • PS/2 keyboard
  • EHCI debug
  • TPM
  • infrared module
  • chassis intrusion header
  • chassis speaker header


  • USB
  • S3 suspend/resume
  • Gigabit Ethernet
  • integrated graphics
  • PCIe (but not the 16x slot, see Known issues)
  • SATA
  • PS/2 mouse
  • serial port
  • hardware monitor (see Known issues)
  • onboard audio
  • front panel audio
  • initialisation with Haswell mrc version 1.6.1 build 2
  • graphics init with libgfxinit (see Known issues)
  • flashrom under the vendor firmware
  • flashrom under coreboot
  • Wake-on-LAN
  • Using me_cleaner


| Northbridge      | Intel Haswell                                    |
| Southbridge      | Intel Lynx Point (H81)                           |
| CPU              | Intel Haswell (LGA1150)                          |
| Super I/O        | Nuvoton NCT6776                                  |
| EC               | None                                             |
| Coprocessor      | Intel Management Engine                          |