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WiFi on the Acer Aspire One

Chipset: Atheros AR2425

Change Regdomain

The WiFi card comes set to regdom 0x65 (World/ETSI C) which limits the channels to 1..11. (iw list shows channels 12..14 as disabled.) In Germany, there are also channels 12 and 13 which are unusable this way. But there’s the tool ath_info which can read and write the EEPROM on the card and thus also the regdomain.

First, find the base address of the adapter using

lspci -vv

Mine was at address 75200000. Now you can dump the contents of the EEPROM using

ath_info 0x75200000

To write the EEPROM, you have to unlock it by setting a GPIO register, namely the first, to zero. I changed the regdomain to 0x00 (=ALL channels available) 0x68 (=EU1 World) using this command:

ath_info -g 1:0 -w 0x75200000 regdomain 68

You can find all valid codes by looking at the DMN_ constants in the regdom.h file.

After unloading the modules: ath5k, ath, mac80211 and cfg80211 and doing a modprobe ath5k, the command iw list should show the two new channels enabled.

For older ieee80211 modules, there’s a module option ieee80211_regdom for the cfg80211 module. This takes the values US, JP or EU. Add the following lines to /etc/modprobe.d/options:

options cfg80211 ieee80211_regdom=EU
options lbm_cw_cfg80211 ieee80211_regdom=EU

And after a reboot, you will have channels 12 and 13 available.

On Jaunty, you have to install the package iw and use the following command in e.g. your /etc/rc.local to set the regdomain to Germany:

iw reg set DE

Possible errors

If you get the message MAC revision 0xffff is not supported! it means that some other module, likely ath_hal and/or ath_pci took over your card.

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