Try this you guys..
Though it says omap4, it worked on my qualcomm (touchpad).
Use that as a Root FileSystem..
There is also a 12 and 11.10 thread.
Take a look at the kernel configs we use. And our ramdisk. You will need to use uimage-extract from moboot to seperate the kernel and ramdisk from uImage.
Look at the configs.. Ubuntu needs V4L stuff for the kernel. Look at the init in the ramdisk. Change them to work for the Nexus 10.
Good luck! Feel free to look at the touchpad rootfs.. We don't run Unity.... Though.. I should try to recompile the latest freedreno stuff.
It should at least boot.. Ours does for moboot and the touchpad. We had to alter xorg and stuff for video.. You can also create a ram console kernel. This is nice, as you can adb into ubuntu without installing adb as it's built into the kernel. Rob Clark from Freedreno taught me that.
Something to read:
Anyhow, Ubuntu 13.04 will improve support for this latest ARM Chromebook to run Google's OS. The Ubuntu 13.04 repository just received ARM's new universal X.Org graphics driver, a.k.a. the xf86-video-armsoc DDX. This is a generic ARM SoC DDX driver for the X.Org Server originally derived from the xf86-video-omap driver.
Other then that, there seem to be only 2 open source gpu drivers other then xf86-video-armsoc... lima and freedreno.