Building the radeon driver into the Linux kernel, that means not as a module,
*without* an initrd image, the firmware is not loaded.

The firmware is present on the filesystem in `/lib/firmware/`, but it has not
been mounted yet.

The firmware can be added using `EXTRA_FIRMWARE`, but that makes it difficult
if the Linux kernel should be shared between different systems using different
hardware generations.

(The best solution would be to not require firmware at all.)

It’d be great if the driver supported to load firmware after the initialization
phase.