OpenWRT, Atheros & channel availability

If you’re living outside the US, and you’re using OpenWRT (a fantastic 3rdparty opensource firmware for many routers), you might have noticed that not all the WiFi channels which are legally allowed in your region are actually available for you to choose from.

This is a known issue, and stems from the fact that the OpenWRT images are built without CONFIG_ATH_USER_REGD=y (which allows overriding the wifi-card builtin default regulatory domain), so that the builds are compliant with the regulations of the US. (see trac ticket 6923)
If you pick another region in the settings, the ROM will pick the most restrictive of the two – in my case this means that WiFi channels 12 and 13 are not available to choose from.

There are two ways to get around this:

  • Building OpenWRT from source, and enabling this option
  • Using reghack to patch the drivers (see the README on how to do this)

I only recently learned of reghack (thanks, Stijn!) which works nicely ;)