Ubuntu 13.10 fails to start X11 on a Macbook Pro with retina display, and it fails to start X11 on VirtualBox when EFI mode is turned on. Even the failover mode fails. This has been tried with 64-bit version of Ubuntu 13.10. Machines: a 2013 Macbook Pro; and a virtual VirtualBox 4.3.6 machine configured for Ubuntu (64-bit) OS, with EFI turned on.
Ubuntu's failover configuration tries to use vesa module, which is not available when running under native EFI or UEFI mode.
Let's fix this by using fbdev module.
Hit ctrl+alt+f1 to switch to console.
Type sudo -i to become root.
Now let's fix the relevant files:
sed 's/Driver.*"vesa"/Driver "fbdev"/' xorg.conf.failsafe > xorg.conf
Restart X11 et al: service lightdm restart
If necessary, switch to the VT dedicated to X11: hit ctrl+alt+f7
Note that the screen will stay blank for a while longer; give the system some time to proceed.
In short, if you're a GNU/Linux user of Firefox (e.g. Firefox on Ubuntu and Iceweasel on Debian) you may want to get backspace to actually go back one page, like many browsers do (did?):
In addressbar, type about:config
If asked, confirm you want to change settings
In search, type browser.backspace_action
Set the value of browser.backspace_action to 0 (that is zero, not letter O) Zero is Windows default and makes pressing backspace go back in history; One is old Linux default and scrolls page up; Two is new Linux default and, like any other integer, simply unmaps the backspace key.