The issue here is that the rPI requires driver code running inside OpenBSD that is a closed source blob.
There are several blobs that are necessary to be on the sd-card for boot: bootcode.bin, fixup.dat, and start.elf. Any bootable sd-card image for the Pi has them.
What's kind of interesting is that most of what start.elf is is actually an entire OS (ThreadX, I believe), that is running on the VC4 GPU in parallel to the OS on the ARM CPU; and that most of the Linux GPU drivers for it are just shims that send messages saying "hey, ThreadX, would you mind doing this for me?"
- the VC4 starts up and a ROM starts executing - the ROM loads bootcode.bin into the SRAM - bootcode.bin sets up the DRAM and loads the start.elf and fixup.dat - the start.elf sets up the ARM core and loads the Linux kernel
ARM code only starts executing at the last stage.
The only bit that's actually necessary on the SD card is the bootcode.bin --- everything else is under the control of whatever's in there.
And the bootloader had been reverse engineered (quite accurately, btw., although all the ISA mnemonics are totally made up). It should be possible now to rebuild it from assembly source.
The main blobs are being run on the GPU, as bootloaders, even before the actual operating system is loaded. OpenBSD does not need to run _any_ blob itself.
There used to be a 3d graphics driver blob, but afaik that got open sourced. Also, if you don't do 3d, you wouldn't even need it.
I don't know exactly what the situation is. Don't care. I have a BeagleboneBlack if I wanted to watch the paint dry doing a build. :)
The rPi boot process requires several files to be on a FAT partition on an sd-card: bootcode.bin, fixup.dat, start.elf, config.txt and the OS kernel; the first 3 of which are blobs.
Would those blobs need to be included, or would OpenBSD be fine saying "use your existing boot card, just drop in our kernel", or "go grab these files from https://github.com/raspberrypi/firmware/tree/master/boot when formatting the sd-card."?
