Raspberry Pi, the free board ?

I used rapsberry pi for few years now, but always with rasbian distribution. And now i have decided to train myself to drivers development and do it on rapsberry pi or others embedded platfoms.

So I have installed a basic linux with buildroot (wich by the way, I recommend it. It's really easy-to-use and powerfull for embedded development). I set the default configuration for raspberry on buildroot, and what suprise, no fucking way to install a real bootloader (like u-boot). You have a shitty GPU firmware/bootloader with closed source and no way to replace it.

The only way to interact with it, it's by 2 files : cmdline.txt, to pass you kernel command line, and with config.txt to tell some basic stuff like the kernel image name. You can boot an u-boot after the GPU firmware, but you add an other boot stage, and it doesn't change the main problem : You don't use open-source software ...

Everywhere you can hear: "Oh Raspberry pi it's amazing, it's all open-source and low cost board.". Yes it's a low cost, and you can do some cool stuff, but it's not really open source. So please stop saying, rapsberry is great and fully free and open-source, it's not.