On: Building Bare-Metal ARM Systems with GNU

Ah yes, so the gcc must be by ARM and the PPA by Terry Guo:

https://launchpad.net/~terry.guo/+archive/gcc-arm-embedded

And yes, this is super-easy:

Step1: Inside Ubuntu, open a terminal and input "sudo add-apt-repository ppa:terry.guo/gcc-arm-embedded"

Step2: Continue to input "sudo apt-get update"

Step3: Continue to input to install toolchain "sudo apt-get install gcc-arm-none-eabi"