I have a laptop that came with Windows and an HDMI port. I installed Ubuntu 12.04 on the laptop.

If I boot up in Windows, connect my computer and tv via HDMI, turn on my tv and select HDMI as the tv's source, I get my computer's display on my tv.

When I try the same having booted up in Ubuntu, I get nothing. If I then go to Displays, my tv's not shown as an alternative display to my laptop screen.

What should I be doing to get my tv as an alternative display? It's a pain to have to switch to Windows when I want to take advantage of the tv's bigger picture.