Lenovo ThinkPad T420s

This article is dedicated to getting hardware specific to the Lenovo ThinkPad T420s.

Hardware overview
The ThinkPad T420s laptops are using the Intel Intel QM67 chipset with Sandy Bridge (Intel HD 3000) or discrete Nvidia graphics.

Installation Prep
This is an example of my current /etc/make.conf for T420s without discrete graphics. Note that GCC Versions before 4.6 will not detect the right CFLAGS for the Core i5 CPU with -march=native (they will use -march=core2 instead of -march=corei7-avx), but it will still work fine.

GRUB Bootloader Config
For GRUB the Sandy Bridge needs some more special kernel parameters to reach the optimal performance and save some battery power. Add this to your kernel command line: