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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 M4A785T-M board. The main difference between the ASUS M4A785-M and the M4A785T-M is the support of DDR3 on the latter.


RAM issue

  • 32bit untested.
  • 64bit was tested and works with 2G of RAM.
    • When using more than 4G of RAM, I can't boot GNU/Linux anymore:
      • USB devices not seen, some errors -71), with mem=4000M, that works ok again.
      • SATA devices are also not seen, and with mem=4000M, it also works ok again.


Device/functionality Status Comments
CPU works OK Tested: AMD Athlon64 X2 240e.
L1 cache enabled Unknown How to test?
L2 cache enabled Unknown How to test?
L3 cache enabled N/A
Multiple CPU support N/A
Multi-core support Unknown
Hardware virtualization Unknown
DDR2 Unknown
DDR3 No 2G works, 4G or more have issues.
Dual channel support Untested
ECC support Untested I'm not sure if hardware supports it.
On-board Hardware
On-board IDE 3.5" Untested
On-board IDE 2.5" N/A
On-board SATA Untested At least 2 of the 6 SATA port works. The rest is untested.
On-board SCSI Unknown
On-board USB OK tested in SeaBIOS and with the linux-libre kernel.
On-board VGA Untested I only tested the external GPU, see below for more informations.
On-board Ethernet OK Tested in linux-libre and ipxe, works flawlessly.
On-board Audio Untested Not tested but it boots fine with it and the sound card appears.
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 OK Tested booting on an ATA sil card: booting on it works when adding its PCI ID to coreboot.
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 Untested
PCI Express x4 add-on cards Untested
PCI Express x8 add-on cards Untested
PCI Express x16 add-on cards OK Works with "02:00.0 VGA compatible controller [0300]: NVIDIA Corporation GT218 [GeForce 210] [10de:0a65] (rev a2)"
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. There seem to be an unpopulated header for it.
Serial port 1 (COM1) OK 10 pins intel header
Serial port 2 (COM2) N/A
Parallel port Untested Headers on board only.
PS/2 keyboard Untested
PS/2 mouse Untested
Game port N/A
Infrared Untested
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 Untested
Hardware watchdog Untested
SMBus Unknown
CAN bus N/A
CPU frequency scaling Untested
Other powersaving features Untested
ACPI Untested
Reboot OK
Poweroff OK
Suspend Unknown
Nonstandard LEDs Untested
High precision event timers (HPET) Untested
Random number generator (RNG) Untested
Wake on modem ring Untested
Wake on LAN Untested
Wake on keyboard Untested
Wake on mouse Untested
TPM Unknown
Flashrom OK Works fine from coreboot to coreboot, and from BIOS to coreboot. From coreboot to BIOS works but you may have to do some tricks like clearing CMOS to make it start again.

proprietary components status

  • Optional CPU Microcode
  • Optional VGA option rom: wihtout it you will get no graphics, Note that if you use an external graphic card, SeaBIOS load the option rom with its default configuration from the graphic card.
    • You can also patch SeaBIOS to put the option rom in memory without running it. That way the linux driver will then find the option rom bytecodes and tables to initialize that GPU.
From 83bbd30b3ef76fc346c417fa08ba716b4e2fb179 Mon Sep 17 00:00:00 2001
From: Denis 'GNUtoo' Carikli <>
Date: Sat, 7 Mar 2015 15:39:52 +0100
Subject: [PATCH] Kconfig: Add option not to run option roms

Signed-off-by: Denis 'GNUtoo' Carikli <>
 src/Kconfig      | 8 ++++++++
 src/optionroms.c | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/src/Kconfig b/src/Kconfig
index b873cd3..2438ab7 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -403,6 +403,14 @@ menu "BIOS interfaces"
         default y
             Support Post Memory Manager (PMM) entry point.
+        depends on OPTIONROMS
+        bool "Put the option roms in memory, but don't run them"
+        default n
+        help
+            Some GPU drivers are capable of initializing the display alone,
+            but they still require some data from the option rom.
     config BOOT
         bool "Boot interface"
         default y
diff --git a/src/optionroms.c b/src/optionroms.c
index c81eff2..c7c89da 100644
--- a/src/optionroms.c
+++ b/src/optionroms.c
@@ -53,7 +53,9 @@ __callrom(struct rom_header *rom, u16 offset, u16 bdf)
 callrom(struct rom_header *rom, u16 bdf)
     __callrom(rom, OPTION_ROM_INITVECTOR, bdf);
 // Execute a BCV option rom registered via add_bcv().

Building the serial port adapter

The serial port is available on the 10 pin "intel" header.

Adapting GNU/Linux

Add mem=4000M to the kennel cmdline, that can be done by adding the following to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and regenerating grub.cfg:



  • Add defaults for the nvram settings.
  • find a clean way to merge the patch for the PCIe graphic card.
  • fix the Audio CODEC(it's the same than the x60 and it works on the x60)Test audio
  • Fix RAM layout to prevent issues with more than 4G of RAM
  • lock SMM/SMI if it's not already
  • make it possible to run the BIOS under serialICE
  • Native GPU init for ATI and Nvidia GPUs


  • Selecting the ASUS M4A77TD-PRO mainboard makes the serialICE shell appear once flashed(however running the BIOS under SerialICE fails at some point).


WARNING, This Howto is for SerialICE and not for coreboot, don't flash the resulting image unless you really know what you're doing...
git clone
cd serialice
make menuconfig
cd ../
cd qemu-0.15.x
ln -s ../SerialICE/simba/*.lua ./

Add the following to asus_m4a77td_pro.lua:

microcode_patchlevel_eax = 0x010000b7

function do_mainboard_setup()
	enable_hook(cpumsr_hooks, filter_amd_microcode)


It fails like that(it inits the 2 cores and we have 1 core(qemu)):

[fffc06a:0c0f] e25f.e260   LAPIC: [00000380] <= 00000000
[fffc06a:1321] e26b.e26d   PCI: 0:18.0 [60] => 00010000
[fffc06a:12e3] e273.e275   PCI: 0:18.3 [e8] => 00075f79
[fffc06a:1397] e27e.e27f   CPUID: eax: 00000001; ecx: 0000001b => 00100f62.00020800.00802009.178bfbff
[fffc06a:1321] e290.e292   PCI: 0:18.3 [e8] => 00075f79
[fffc06a:1397] e297.e298   CPUID: eax: 00000001; ecx: 0000001b => 00100f62.00020800.00802009.178bfbff
[fffc06a:121e] e2a5.e2a6   CPUID: eax: 80000001; ecx: 0000001b => 00100f62.10001b26.000037ff.efd3fbff
[fffc06a:12ff] e2bb.e2bc   CPUID: eax: 80000008; ecx: 0000001b => 00003030.00000000.00002001.00000000
[fffc06a:130c] e2bf.e2c0   CPU MSR: [c001001f] => 00584000.00000008
[fffc06a:131d] e2c4.e2c5   CPU MSR: [c001001f] <= 00584000.00000008
[fffc06a:131d] e2cf.e2d1   PCI: 0:18.3 [90] => 00000000
[fffc06a:1348] e2dc.e2dd   CPUID: eax: 80000008; ecx: 0000001b => 00003030.00000000.00002001.00000000
[fffc06a:135d] e2e2.e2e3   CPU MSR: [c001001f] <= 00584000.00000008
[fffc06a:0b7d] e2f2.e2f3   CPU MSR: [0000001b] => 00000000.fee00900
[fffc06a:0b7d] e2f4.e2f5   LAPIC: [00000020] => 00000000
[fffc06a:127a] e2f9.e2fa   CPUID: eax: 00000001; ecx: 0000001b => 00100f62.00020800.00802009.178bfbff
[fffc06a:1289] e2f9.e2fb   CPUID: eax: 80000008; ecx: 00802009 => 00003030.00000000.00002001.00000000
[fffc06a:1057] e302.e304   PCI: 0:18.0 [68] => 004fac0f
[fffc06a:1071] e30d.e30f   PCI: 0:18.0 [68] <= 004fac2f
Readback error! 30/72
Readback error! a/63
Readback error! 72/30
Readback error! 3e/30
Readback error! 20/30
Readback error! 63/30
Readback error! 66/30
Readback error! 45/30
Readback error! a/31
Readback error! 52/62
Readback error! 3e/2e
Readback error! 52/66
Readback error! 20/66
Readback error! 4f/66
Readback error! 30/65
Readback error! 52/62
Readback error! a/30
Readback error! a/30
Readback error! 3e/30
[fffc06a:0c50] e31d.e31e   CPU MSR: [0000001b] => 00000000.00000000