The previous method only configured serial console for Ubuntu or Fedora, I noticed this wasn't working when I built RedHat 7. After reading about how grub-mkconfig works, I realized that we shouldn't be using sed to modify grub.cfg, and set up the proper variables in /etc/default/grub Change-Id: I02b73dc5074cb48a716849cb8a8a9b2f054bea31