Configuring Raspberry Pi 3 via Serial Console

I got several RPi 3 recently. I tried to set them up via the UART console as I did with RPi 2. But I could not see anything on my computer. After googling around, I found that the serial console is disabled by default. So I added enable_uart=1 to /boot/config.txt. And then I could see login prompt on my computer.
As RPi 3 has a builtin WiFi module, I can connect it to my wireless router and access it via SSH. If the network is secured with WPA2-PSK, just add the following to /etc/wpa_supplicant/wpa_supplicant.conf.

network={
    ssid="your_ssid"
    psk="your_password"
}

If your wireless network is open, add the following.

network={
    ssid="your_ssid"
    key_mgmt=NONE
}

and run sudo ifdown wlan0 and then sudo ifup wlan0. You can test the connection with ifconfig, pingand iwconfig.

Adding an Intel Wireless-AC 7260 Card on ThinkPad T420s

I bought an Intel 7260AC card from jd.com yesterday in order to replace the 6205 card on my T420s and enjoy the speed of 11ac. The card arrived this morning. The card is not specially made for ThinkPads.

As all ThinkPad's BIOS is equipped with a whitelist of authorized wirless cards. I need to flash a BIOS with whitelist removed. I found one made by TimeWalker75a on bios-mods.com. Here is the link. Apart from removing the whitelist, the modified BIOS also unlocks RAM clock speed and some advanced settings. But before flashing the modified BIOS, you need to flash the original 1.41 BIOS offered by Lenovo.

Then, I removed the battries and the shield above the RAM modules and saw the 6205 mini-PCI-E wireless card. I unplugged the two antenna cables, loosed the screw and removed the old card. And then installed the new 7260 card and plugged the cables. The gray cable should be connected to the main port while the black one should be connected to the aux port.

I plugged in the power cord and turn it on. Fedora identified the new card successfully, and the hardware wireless switch worked flawlessly. But all WiFi history is lost. This 7260AC card also contains a Bluetooth 4.0 module, and the laptop also has a embedded Bluetooth module(BCM2045B) from Broadcom, I can see both of them by running hciconfig. Removing BCM2045B needs opening the palm rest. I found a way to blacklist it with udev at here.

Update:

Do not remove the embedded BCM2045B module, or the BIOS will disable Bluetooth even if there is one module in 7260.