The Raspberry Pi is (perhaps until now) unable to boot without the
proprietary driver. This quote is from the FSF single board computer page:
----
The Raspberry Pi requires nonfree software to start up. It can't reach the
point of executing free software unless this nonfree program is part of the
installed system software.
The startup program is, in fact, the same program that runs the GPU and the
video decoding hardware. Thus, the GPU and the video decoding hardware are
unusable in the free world, but these jobs can be done with free software on
the CPU.
That program appears to implement intentional restrictions, such as blocking
the video decoding hardware for MPEG-2 and VC-1 in the absence of a key that
is specific to the machine in hand.
