Changing scheduling parameters in Linux

Process scheduling within Linux is done by the kernel, following different aspects. Usually it's goal is to share all resources fairly among all running processes.

Sometimes, there's a need to tell the kernel explicitly to prior some process, bind some process to a special CPU and so on.

Changing process priorities is commonly known:

nice -n 10 make

runs the program make with a priority of 10 (-20 meaning most favorable and 19 least favorable scheduling). If you want to change a priority of a running program, renice is your choice. Continue reading

Framebuffer on ALIX.3D3

ALIX.3D3 booting

ALIX.3D3 booting

In contrary to most ALIX devices, the ALIX.3D3 has an integrated VGA controller and an Award BIOS (tinyBIOS doesn't support VGA), so why not attach a monitor.

Standard text mode is supported by default (and faster than graphical mode), but if you wish to change resolution, add a boot logo or even want to use a graphical boot screen like splashutils a framebuffer device is needed.

lspci lists the integrated VGA controller of the AMD Geode LX800 CPU as the video device:

00:01.1 VGA compatible controller: Advanced Micro Devices [AMD] Geode LX Video

Luckily the linux kernel supports this device directly and so no VESA framebuffer is needed. Continue reading

Installing Gentoo on ALIX.3D3

When I ordered the ALIX.3D3 board I thought installing Gentoo on this should be a piece of cake, but finally there were some stumbling blocks and that's why I want to summarize how I got gentoo running.

First of all, I recommend installing Gentoo on a normal desktop to get to know the installing process, which is a bit different from graphical installers of mainstream distros. The Gentoo Handbook is a great documentation how this done.

To install gentoo, you have to boot a minimal or "rescue" linux usually from cd/dvd. I tried to convice the bios to boot from a usb cd-rom drive, but I hadn't any success. Continue reading

Temperature sensor on ALIX.3D3

LM86 on ALIX.3D3

LM86 on ALIX.3D3

The schematics of the ALIX.3D3 mention a temperature sensors LM86 on page 2 which external sensors pins are connected to the TDP/TDN pins of the Geode LX800 CPU. So this sensor should be able to measure CPU and mainboard temperature.

The LM86 ist connected by the SMBus (which is compatible to I²C if bus speed is below 100kHz, see Maxim's Appnote for detailed comparison) via the AMD CS5536 Geode companion. Continue reading