1 2 BCM43xx Linux Driver Project 3 ============================ 4 5Introduction 6------------ 7 8Many of the wireless devices found in modern notebook computers are 9based on the wireless chips produced by Broadcom. These devices have 10been a problem for Linux users as there is no open-source driver 11available. In addition, Broadcom has not released specifications 12for the device, and driver availability has been limited to the 13binary-only form used in the GPL versions of AP hardware such as the 14Linksys WRT54G, and the Windows and OS X drivers. Before this project 15began, the only way to use these devices were to use the Windows or 16OS X drivers with either the Linuxant or ndiswrapper modules. There 17is a strong penalty if this method is used as loading the binary-only 18module "taints" the kernel, and no kernel developer will help diagnose 19any kernel problems. 20 21Development 22----------- 23 24This driver has been developed using 25a clean-room technique that is described at 26http://bcm-specs.sipsolutions.net/ReverseEngineeringProcess. For legal 27reasons, none of the clean-room crew works on the on the Linux driver, 28and none of the Linux developers sees anything but the specifications, 29which are the ultimate product of the reverse-engineering group. 30 31Software 32-------- 33 34Since the release of the 2.6.17 kernel, the bcm43xx driver has been 35distributed with the kernel source, and is prebuilt in most, if not 36all, distributions. There is, however, additional software that is 37required. The firmware used by the chip is the intellectual property 38of Broadcom and they have not given the bcm43xx team redistribution 39rights to this firmware. Since we cannot legally redistribute 40the firwmare we cannot include it with the driver. Furthermore, it 41cannot be placed in the downloadable archives of any distributing 42organization; therefore, the user is responsible for obtaining the 43firmware and placing it in the appropriate location so that the driver 44can find it when initializing. 45 46To help with this process, the bcm43xx developers provide a separate 47program named bcm43xx-fwcutter to "cut" the firmware out of a 48Windows or OS X driver and write the extracted files to the proper 49location. This program is usually provided with the distribution; 50however, it may be downloaded from 51 52http://developer.berlios.de/project/showfiles.php?group_id=4547 53 54The firmware is available in two versions. V3 firmware is used with 55the in-kernel bcm43xx driver that uses a software MAC layer called 56SoftMAC, and will have a microcode revision of 0x127 or smaller. The 57V4 firmware is used by an out-of-kernel driver employing a variation of 58the Devicescape MAC layer known as d80211. Once bcm43xx-d80211 reaches 59a satisfactory level of development, it will replace bcm43xx-softmac 60in the kernel as it is much more flexible and powerful. 61 62A source for the latest V3 firmware is 63 64http://downloads.openwrt.org/sources/wl_apsta-3.130.20.0.o 65 66Once this file is downloaded, the command 67'bcm43xx-fwcutter -w <dir> <filename>' 68will extract the microcode and write it to directory 69<dir>. The correct directory will depend on your distribution; 70however, most use '/lib/firmware'. Once this step is completed, 71the bcm3xx driver should load when the system is booted. To see 72any messages relating to the driver, issue the command 'dmesg | 73grep bcm43xx' from a terminal window. If there are any problems, 74please send that output to Bcm43xx-dev@lists.berlios.de. 75 76Although the driver has been in-kernel since 2.6.17, the earliest 77version is quite limited in its capability. Patches that include 78all features of later versions are available for the stable kernel 79versions from 2.6.18. These will be needed if you use a BCM4318, 80or a PCI Express version (BCM4311 and BCM4312). In addition, if you 81have an early BCM4306 and more than 1 GB RAM, your kernel will need 82to be patched. These patches, which are being updated regularly, 83are available at ftp://lwfinger.dynalias.org/patches. Look for 84combined_2.6.YY.patch. Of course you will need kernel source downloaded 85from kernel.org, or the source from your distribution. 86 87If you build your own kernel, please enable CONFIG_BCM43XX_DEBUG 88and CONFIG_IEEE80211_SOFTMAC_DEBUG. The log information provided is 89essential for solving any problems. 90