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ASUS KCMA-D8

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This page describes the steps necessary to get most out of the ASUS KCMA-D8 hardware. It assumes that you have already successfully installed Arch Linux.

BIOS

The manufacturers BIOS is outdated, has no NVMe drivers and is closed source. To remedy this, we can install a precompiled open source coreboot distribution, coreboot-15h.

The stock BIOS prevents you from flashing it with a non-OEM BIOS, so the first flash must be done via hardware. The easiest way to install coreboot-15h for the first time is with a Raspberry Pi, connecting the bios chip to the GPIO as seen here. Install flashrom on the Pi with apt install flashrom, download and extract the latest SeaBIOS + uCode + VGA-OpROMs image from the KCMA-D8 page, and then follow the how to use flashprog instructions to backup and flash the BIOS (replacing ./flashprog with flashrom). Make sure to clear the CMOS before booting with the new BIOS. Setting spispeed=8192 in the command flags is recommended to improve stability and reliability.

Note Make sure to backup the stock BIOS if you're overwriting it. Take 3 dumps and compare their sha1sum. For older W25Q16 OEM BIOS chips, pins 3 (WP) and 7 (HOLD) must also be connected to pin 8 (VCC) to allow read and write.

Once coreboot-15h has been installed, it can be updated from within the operating system by installing flashrom and following these instructions (replacing ./flashprog with flashrom).

The stock BIOS chip is 2MiB, and can be upgraded to a 16MiB one such as the 25Q128FVIQ or the W25Q128FVSG with a SOP8 to DIP8 adapter PCB. This will allow more space for larger payloads in the future, but isn't strictly necessary.

Note If using a larger BIOS chip, one should repeat the image to fill up the extra space rather than padding it with zeros. This can be done via cat source_file source_file source_file source_file source_file source_file source_file source_file > output_file for example.

Libreboot will be implementing coreboot-15h soon, and this will be an alternative up-to-date coreboot distribution.

Sensors

After running sensors detect, it loads the incorrect kernel driver w83627ehf. This can be remediated by replacing w83627ehf with w83795 in lm_sensors configuration file: 

/etc/conf.d/lm_sensors
HWMON_MODULES="w83795"

The enumerated hwmon symlinks located in /sys/class/hwmon/ may vary in order after a power cycle, because the kernel modules do not load in a consistent order every boot. Something as simple as plugging in a game controller could cause the order to change. Creating/editing /etc/modules-load.d/modules.conf in such a manner should create a defined order for the modules to load in, which should make the hwmon paths stay where they are and not change order upon reboot: 

/etc/modules-load.d/modules.conf
# Load w83795 at boot
w83795

This method may not always work consistently, and a more reliable method should be documented and implemented.

Fan control

Fan control in this motherboard is quite unusual. There is 8 PWM fan control channels, however only 2 channels are used for controlling the fan speed of all 8 fan headers. One must use a combination of 4 pin fans (recommended for CPU), and 3 pin fans (recommended for case). One speed can be set for all of the 4 pin fans, and another speed can be set for all of the 3 pin fans. After running pwmconfig, fancontrol.service refuses to start. This is because fancontrol cannot associate more than 2 fans with PWM speed. Manually configure /etc/fancontrol so that FCFANS only has two inputs per device, and restart fancontrol.service. Here is an example configuration: 

/etc/fancontrol
INTERVAL=10
DEVPATH=hwmon6=devices/pci0000:00/0000:00:14.0/i2c-8/8-002f
DEVNAME=hwmon6=w83795g
FCTEMPS=hwmon6/device/pwm2=hwmon6/device/temp1_input hwmon6/device/pwm1=hwmon6/device/temp8_input
FCFANS=hwmon6/device/pwm2=hwmon6/device/fan8_input+hwmon6/device/fan6_input hwmon6/device/pwm1=hwmon6/device/fan2_input+hwmon6/device/fan1_input
MINTEMP=hwmon6/device/pwm2=60 hwmon6/device/pwm1=40
MAXTEMP=hwmon6/device/pwm2=80 hwmon6/device/pwm1=65
MINSTART=hwmon6/device/pwm2=60 hwmon6/device/pwm1=60
MINSTOP=hwmon6/device/pwm2=0 hwmon6/device/pwm1=0

Gaming Boost Clocks

Gaming on the KCMA-D8 is quite attainable with a pair of Opteron 4332 HE / 4386 CPU's and some 1333-1600MHz RAM. However, there are a few things you can do to improve the experience. For example, the 4386's all core max turbo is 3.1GHz, however they can boost to 3.8GHz on 2 cores 4 threads (2 modules) when the other 2 cores 4 threads (2 modules) are not as busy. Since these CPU's have plenty of threads, we can simply disable half of the cores/modules and get a massive single threaded boost. The recommended way to do this is with cpupower-gui-gitAUR.

Keep in mind that inter-CPU communication introduces latency that isn't usually desirable for games, so restricting all of the game threads and memory to run on NUMA node 0 is often desirable. See numactl(1) for setting NUMA affinity.

IPMI Module

This motherboard supports an ASMB4 IPMI Module. The manufacturers ROM for the IPMI module is massively insecure and has incompatibilities with coreboot. See 15h.org's AST2050 page for their compatible open source BMC firmware replacement.