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The wiki is being retired!

Documentation is now handled by the same processes we use for code: Add something to the Documentation/ directory in the coreboot repo, and it will be rendered to Contributions welcome!

This HOWTO explains how to use coreboot on the ASUS M4A78-EM board.


Device/functionality Status Comments
CPU works OK Tested: AMD Sempron 140.
L1 cache enabled OK -
L2 cache enabled OK -
L3 cache enabled N/A
Multiple CPU support N/A
Multi-core support Untested
Hardware virtualization Untested -
DDR2 OK 1G tested
Dual channel support Untested
ECC support Untested
On-board Hardware
On-board IDE 3.5" OK Tested: CD/DVD-RW
On-board IDE 2.5" N/A
On-board SATA OK Tested: SATA port 1.
On-board SCSI Unknown
On-board USB OK Mouse attached crashes SeaBIOS
On-board VGA OK Tested: DVI and analog VGA. Untested: HDMI.
On-board Ethernet OK
On-board Audio Untested -
On-board Modem N/A
On-board FireWire N/A
On-board Smartcard reader N/A
On-board CompactFlash N/A
On-board PCMCIA N/A
On-board Wifi N/A
On-board Bluetooth N/A
On-board SD card reader N/A
Add-on slots/cards
ISA add-on cards N/A
Audio/Modem-Riser (AMR/CNR) cards N/A
PCI add-on cards Unknown Recognized, but operation unstable
Mini-PCI add-on cards N/A
Mini-PCI-Express add-on cards Unknown
PCI-X add-on cards N/A
AGP graphics cards N/A
PCI Express x1 add-on cards Untested
PCI Express x2 add-on cards N/A
PCI Express x4 add-on cards N/A
PCI Express x8 add-on cards N/A
PCI Express x16 add-on cards Untested
PCI Express x32 add-on cards N/A
HTX add-on cards N/A
Legacy / Super I/O
Floppy N/A There is no floppy connector at all.
Serial port 1 (COM1) OK COM1 is only pin header on board. DB-9 serial connector is available, but not included with board.
Serial port 2 (COM2) N/A
Parallel port Untested No connector, pin header on board only.
PS/2 keyboard OK
PS/2 mouse N/A
Game port N/A
Infrared N/A
PC speaker Untested
DiskOnChip N/A
Trackpoint N/A
Touchpad N/A
Fn Hotkeys N/A
Fingerprint Reader N/A
Docking VGA N/A
Docking LAN N/A
Docking USB N/A
Docking Audio N/A
Docking Displayport N/A
Thinklight N/A
Webcam N/A
Sensors / fan control OK Single temperature reported.
Hardware watchdog Untested
SMBus Unknown
CAN bus N/A
CPU frequency scaling OK Powernow-K8 works.
Other powersaving features Untested
ACPI Untested -
Reboot No
Poweroff No
Suspend Unknown
Nonstandard LEDs N/A
High precision event timers (HPET) No Linux detects, but disables HPET.
Random number generator (RNG) Untested
Wake on modem ring Untested
Wake on LAN
Wake on keyboard Untested
Wake on mouse Untested
TPM Unknown
Flashrom OK

Building coreboot

See the Build HOWTO for general information on how to build coreboot.

This board is very similar to ASUS M4A785-M. The major differences are

  • Chipset is AMD 780G and SB700 (instead of 785G and SB710).
  • On-board VGA is ATI Radeon HD3200 (instead of HD4200), PCI id 1002:9610 (instead of 1002:9710), and
  • One of the six SATA ports is eSATA.

There is now (tested on revision 6151) support for M4A78-EM in Coreboot.

Get the Coreboot sources and build tools. Download or build a SeaBIOS binary.

VGA BIOS for the onboard ATI Radeon can be extracted from the original BIOS with the bios_extract utility.

Invoke menuconfig.

  • Select Mainboard to be Asus M4A78-EM, ROM chip size 1 MB.
  • From "Console options" select "Use onboard VGA as primary video device" if you use the onboard ATI Radeon.
  • Add the extracted VGA BIOS, set PCI ids to 1002,9610.
  • Add SeaBIOS payload.

Compile with make and flash.

ROM Chip

Up-to-date Flashrom should be able to detect, read, and write the BIOS ROM. The chip is 8 Mbit cFeon EN25F80. It is in DIP-8 package and installed in a socket, so it can be changed without soldering. The ROM is accessed via the SPI protocol. I also tested a Macronix MX25L8005 chip as a substitute, and it worked fine.

Known issues

  • Disable configuration option "Chipset" -> "Run non-VGA option ROMs" if there are PCI cards with BIOS. PCI card BIOS may need (Sea)BIOS services to run, and crash if invoked from Coreboot directly.
  • Boot succeeds with Intel e100 network card or Tekram TR-822 SATA card, and Linux loads card drivers, but operation was not confirmed. Network card did not manage to transfer data, although link was established. SATA card was tested only for booting. SeaBIOS recognized the controller and drive, but GRUB failed to load completely.


  • 1 GB RAM (1 x Kingston KVR800D2N5/1G) - Boots


  • SeaBIOS version 0.6.1 works
    • Can boot Debian Linux from SATA drive via Grub2.
  • Coreinfo works.
    • Both as standalone payload or loaded from SeaBIOS
    • Both serial port and VGA+PS2 keyboard work.
  • FILO works ok.