The ath_hal module contains the Atheros Hardware Access Layer (HAL). This code manages much of the chip-specific operation of the driver. The HAL is provided in a binary-only form in order to comply with FCC regulations. In particular, a radio transmitter can only be operated at power levels and on frequency channels for which it is approved. The FCC requires that a software-defined radio cannot be configured by the user to operate outside the approved power levels and frequency channels. This makes it difficult to open-source code that enforces limits on the power levels, frequency channels and other parameters of the radio transmitter. See

http://ftp.fcc.gov/Bureaus/Engineering_Technology/Orders/2001/fcc01264.p df for the specific FCC regulation. Because the module is provided in a binary-only form it is marked "Proprietary"; this means when you load it you will see messages that your system is now "tainted". A detailed discussion of the pros and cons of this design can be found at http://madwifi.org/wiki/HAL If you wish to use this driver on a platform for which an ath_hal module is not already provided please contact the author. Note that this is only necessary for new _architectures_; the HAL is not tied to any specific version of Linux - in fact the identical HAL binary code is used unchanged with other operating systems.

-----Original Message----- From: Luke -Jr Sent: Wednesday, February 21, 2007 11:30 AM

On Wednesday 21 February 2007 11:21, Bradley Hook wrote:

...

Luke -Jr wrote:

...

Warning: 'madwifi' is not GPL-compatible; as such, it is

illegal and

...

...

will taint your kernel.

From the COPYRIGHT file in the madwifi tarball:

• Alternatively, this software may be distributed under

the terms of the

...

• GNU General Public License ("GPL") version 2 as

published by the Free

...

• Software Foundation.

Indeed, but that is just a wrapper. This GPL'd wrapper is *distributed along with* a binary blob it links to which is *specifically* not GPL. madwifi-0.9.2.1/hal/COPYRIGHT: All files contained in this distribution are covered by the following copyright unless explicitly identified otherwise. Note that this copyright does _NOT_ contain a "or GPL" clause and does _NOT_ permit redistribution with changes.