Enabling XO features on other distributions

It is fairly straightforward to get Linux distributions to boot and run on the XO, since it is a "just" an X86 computer. The XO has several unique features that require additional steps to enable.

This work is present in the Fedora adaptation that is the normal operating system for OLPC OS images (presumably the changes are either in olpc-specific packages or modifications to Fedora packages, see a recent build log). This page documents the changes that other Linux distributions require.

Input controls

Controlling the backlight

The XO display has two controls

1. The backlight brightness (range 0-15)

control or read the brightness through the sysfs file (as of 2.6.25) /sys/class/backlight/dcon-bl/brightness

2. Display mode (high-res vs simulated RGB)

Control or read the mode through the sysfs file (as of 2.6.25) /sys/devices/platform/dcon/output

The high-res mode is 1200x900, the blurred mode is ~800x600.

A 'normal' display has three color pixels for each display pixel, the XO display has one color for each display pixel, and the color is always on when the backlight is on, so to display a color display (or even a white point). this means that if the mode is not in simulated RGB mode and the backlight is on the display will look very strange as different pixels will have different colors.

the standard software for the XO switches to high-res mode when the backlight turns off completely, and simulated RGB mode when the backlight is on.

• See http://dev.laptop.org/~pgf/brightness.sh.txt for an example script to control the brightness and switch the mode appropriatly.

Gamepad keys

On a traditional PC keyboard, the keypad area to the right contains duplicate arrow, pgup/down and home/end keys that are operational when numlock is not in effect. The gamepad produces the same keycodes that those keypad keys do, thus the dpad produces keypad up/down/left/right, and the circle/cross/square/check keys produce the traditional keypad page up/down and home/end.

You could run a very simple daemon that eavesdrops on an /dev/input/eventNN node in order to support XO's multi-media keyboard keys. if there's not already a packaged way of doing it.

scan keys are

'game keys' rotate press 69 release e9

direction keys up press 65 release e5 down press 66 release e6 left press 67 release e7 right press 68 release e8

buttons O press e0 65 release e0 e5 X press e0 66 release e0 e6 box press e0 67 release e0 e7 check press e0 68 release e0 e8

2nd key from the left on the top row of keys press e0 79 release e0 f9

2nd key from the right on the top row of keys press e0 6e release e0 ee

frame (right key on top row) press e0 5d release e0 dd x/ (below keyboard) press 73 release f3 left hand press e0 5b release e0 db right hand press e0 5c release e0 dc right alt press e0 38 release e0 b8 view source key (fn + space) 59 (fn key) followed by e0 56 release is e0 d6 (the d9 release of the fn key may come before or after the release of the view source key)

Stylus pad

The extended stylus pad either side of the track pad. Note this feature may be removed from future hardware.

Lid sensors

These need to trigger screen off or enter e-book mode.

EC interface

The embedded controller can provide battery info and charge status. This may show up under the power interfaces, may not have stable API.

Mesh mode

XO uses special firmware to implement a early draft of 802.11s mesh networking (??)