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Comment by eloy | Hacker News Reader

That's true. They don't officially support the Raspberry Pi because it needs proprietary drivers and thus breaks the "chain of trust" needed for flashing Libreboot.

It's a bit over-the-top paronoid to expect firmware modifying software in GPU drivers, but I understand their point.

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To call the binary blobs on the Pi "GPU drivers" is an understatement. The VC4 is running the full ThreadX operating system. The Pi is closer to a VC4 board with a secondary ARM coprocessor tacked on than it is to an ARM board.

Oh wow, I didn't knew this. Will look into this, thanks.

All the same, is your adversary really going to use this to attack your machine? They'd have to predict a number of things quite in advance, as well as sneak an attack into the blob.

Hm, well I have always run it headless. Should be possible to make sure the GPU driver isn't ever loaded.

The VC4 GPU actually is the primary chip; it boots the ThreadX operating system on the VC4 first, then ThreadX loads the user-configured system onto the ARM core. Whether you run headless or not, ThreadX is running on the VC4.

> The Raspberry Pi boots from its GPU and only non-free software is currently available for the GPU, even starting the machine requires a large (2MB) blob of non-free, unsupportable software

https://wiki.debian.org/RaspberryPi

Also from that page:

Broadcom publicly released some code, licensed as 3-Clause BSD, to aid the making of an open source GPU driver. The "rpi-open-firmware" effort to replace the VPU firmware blob started in 2016: https://github.com/christinaa/rpi-open-firmware. See more at https://news.ycombinator.com/item?id=11703842

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