https://bugzilla.kernel.org/show_bug.cgi?id=60741
--- Comment #3 from Eastern Heart zxd123314@hotmail.com --- (In reply to Alex Deucher from comment #2)
I'm guessing you are getting a stall due to waiting for the firmware fetch to time out. Make sure your initrd contains the firmware if you are using one or if you are building the driver into the kernel, make sure the firmware is built in as well. If you wait for a few minutes the the firmware fetch will eventually timeout and the kernel will continue. You can also try backlisting radeon and then booting to a non-X runlevel and then try loading radeon manually. At that point the filesystem will be available and the driver will be able to access the firmware.
My /lib is (ofcourse) on the root filesystem. And the whole DRM support is a module. I waited for at least 10 minutes. I know the pain of waiting firmware, but it cannot cost 10 minutes.(I used to have no firmware so I know the time, It's at most 1 min).