(In reply to comment #11)
> Does it boot correctly if you build radeon as a module, then disable radeon
> (add radeon.modeset=0 to your kernel command line in grub) and boot to a
> non-X runlevel, then load radeon manually?
> 
> modprobe -r radeon
> modprobe radeon modeset=1

No, sadly, it still hangs at the same place. Problem is, I can't tell if it
hangs when loading the initramfs or when it tries to initialize the display
beyond that...

Any other suggestion? By the way, I built an 3.11.0-rc2 kernel this morning
with as few drivers as possible for my system, just in case, but without any
luck.