Lenovo Thinkpad X220

Useful external links

 * First and foremost, is the Gentoo installation guide, of course
 * Somewhat organized X220 hints: thinkwiki page
 * X220 gossip: reddit page
 * Instructions for Thinkpad-acpi kernel module
 * Lenovo UVC Camera

Other kernel options
USB announce new devices is also useful.
 * presumably you'll use udev, which asks that you turn on CONFIG_USB_SUSPEND, which for the 3.7.9 kernel you can find via make menuconfig under Device Drivers --> USB support --> Support for Host-side USB --> USB runtime power management .....

Comments

 * RealTek wireless cards are a real problem. If lspci shows your brand new X220 has one, consider returning it to the store and getting one with an Intel wireless card.
 * If you're stuck with the RealTek, install the manufacturer's driver and firmware from their webpage. This reduces the frequency of disconnects. You may have to add a missing "include" statement to get the driver to compile.
 * A desperate thing to try is the ndiswrapper, they support some similar cards. Requires WEXP_PRIV in the kernel config. Only tested as far as the build stage.
 * Not sure how to get the fingerprint reader to replace the password. Defining it as "sufficient" in /etc/pam.d/system-auth isn't enough :-(
 * kernel options are discussed in the links above. The following works well for kernel 3.7.9: