Free Wi-FiΒΆ
It is increasingly hard to find wifi hardware that supports free-as-in-speech drivers - that is finding a USB wifi dongle for your laptop is becoming impossible. So I went to the FSF approved company Tehnoetic and put down some hard-earned for a mini-dongle and a high gain dongle and antenna that assuredly will be using a chipset that has a free driver.
Excitedly I am sitting in a cafe about to plug them in, and why not blog about it.
Plugging in the mini-dongle, I get
[ 502.208147] usb 5-3: new high-speed USB device number 5 using ehci-pci
[ 502.356966] usb 5-3: New USB device found, idVendor=0cf3, idProduct=9271
[ 502.356981] usb 5-3: New USB device strings: Mfr=16, Product=32, SerialNumber=48
[ 502.356991] usb 5-3: Product: UB93
[ 502.356999] usb 5-3: Manufacturer: ATHEROS
[ 502.357007] usb 5-3: SerialNumber: 12345
[ 502.770802] usb 5-3: ath9k_htc: Firmware htc_9271.fw requested
[ 502.770879] usb 5-3: firmware: failed to load htc_9271.fw (-2)
[ 502.770891] usb 5-3: Direct firmware load failed with error -2
[ 502.770898] usb 5-3: Falling back to user helper
[ 502.771133] usbcore: registered new interface driver ath9k_htc
[ 502.775096] usb 5-3: ath9k_htc: USB layer deinitialized
Hmmm.
Lets start by confirming what dmesg tells us - what is the USB device.
Bus 005 Device 005: ID 0cf3:9271 Atheros Communications, Inc. AR9271 802.11n
OK. So its the AR9271 chipset, which apparently uses the ath9k_htc driver. Aha the online blurb (on my iPhone!) tells me ‘firmware is required’
Great, I need a binary firmware (presumably on the Atheros chipset) to run my free driver. This is silly guys. Its the 21C! I really am worried about the state of wifi support in the F/OSS world.
So , I dutifully tether my iPhone with my old-and-not-free dongle, and apt-get install firmware-atheros
[ 1915.380977] usb 5-3: Manufacturer: ATHEROS
[ 1915.380985] usb 5-3: SerialNumber: 12345
[ 1915.381969] usb 5-3: ath9k_htc: Firmware htc_9271.fw requested
[ 1915.400560] usb 5-3: firmware: direct-loading firmware htc_9271.fw
[ 1915.682688] usb 5-3: ath9k_htc: Transferred FW: htc_9271.fw, size: 51272
[ 1915.920587] ath9k_htc 5-3:1.0: ath9k_htc: HTC initialized with 33 credits
[ 1916.195731] ath9k_htc 5-3:1.0: ath9k_htc: FW Version: 1.3
[ 1916.195744] ath: EEPROM regdomain: 0x65
[ 1916.195751] ath: EEPROM indicates we should expect a direct regpair map
[ 1916.195760] ath: Country alpha2 being used: 00
[ 1916.195770] ath: Regpair used: 0x65
[ 1916.200591] ath: EEPROM regdomain: 0x833a
[ 1916.200600] ath: EEPROM indicates we should expect a country code
[ 1916.200606] ath: doing EEPROM country->regdmn map search
[ 1916.200612] ath: country maps to regdmn code: 0x37
[ 1916.200617] ath: Country alpha2 being used: GB
[ 1916.200621] ath: Regpair used: 0x37
[ 1916.200626] ath: regdomain 0x833a dynamically updated by country IE
[ 1916.202135] ieee80211 phy2: Atheros AR9271 Rev:1
[ 1916.520638] systemd-udevd[3209]: renamed network interface wlan0 to wlan3
horaah - it loads the firmware OK. And renames wlan for some reason. Ok, udev is the Linux device manager, and it is the one responsible for loading the firmware and generally dealing with devices attached to the system buses.
udev generates rules (/lib/udev/rules.d/...) and those rules are stored in (/etc/udev/rules.d/70-persistent-net.rules) and they show me
# USB device 0x:0x (rt73usb)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:22:75:fd:d7:8a", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan2"
# USB device 0x:0x (ath9k_htc)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="60:02:b4:99:94:c5", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan3"
So the rules are written each time a new wlan device is found, and the match is based on the, obviously now i think about it, MAC address of the device.
Killing off the previous rules and re-plugging does the needful and I have wlan0 back. I then rerun my tethering script and all is well with the world. uploading this blog post ... now !