I’m not sure if this is the right community for this sort of post. I couldn’t think of any other community to post it in. If there does exist a more appropriate place to post it, then please let me know.
It’s dependent on the manufacturer to decide if they want a black box system management processor, what architecture to use, and what it will be responsible for.
The Raspberry Pi SoC uses the video accelerator processor (VPU) for bootstrapping the ARM CPUs - effectively making the ARM a coprocessor to the VPU. The config.txt and *.elf files you have to put on the SD card are the OS for the VPU and bootloader for Linux that gets loaded to the ARM cores.
I believe yes, but since chip manufacturers are free to use ARM designs to design their chips, the implementations of such a backdoor may differ.
The baseband processor is for devices with cell connections. Something like a Raspberry Pi does not have one.
Apologies, I was thinking of mobile phones as I wrote this comment. You are correct, however I do not trust Broadcom to not bundle spyware with their devices if they can help it
Yes, there are definitely better SBC’s that don’t use Broadcom chips. Some of the Allwinner boards will boot without any blobs as long as you don’t need the GPU.
Could you point me towards them?
The Pine A64, Rock64 & RockPro64 are blob free. The Orange Pi Zero is blob free except for the WiFi.
Thanks
Some arm sbc computers have schematics available. Could someone with equipment for bga components and a means of making pcbs theoretically make a backdoorless one and use it to do all the illegal stuff they want?
There are open source x86s now but homebrewers are just now getting around to making barely working, not even good 386 and 486 stuff so it’ll be a long ass time before open source x86 stuff becomes more viable.
There is no standard for SoCs. If your board has an NXP i.MX6, you can’t just desolder it and drop in a TI Sitara or nVidia Jetson.
Designing a PCB for an SoC isn’t rocket science. There’s nothing magical about the schematic or the layout, and usually the vendor gives out full design files for their eval boards that you can use as a starting point for your product. The silicon is the hard part. You can make your own Beaglebone clone right now for a few hundred dollars including parts and the board, assuming you are comfortable soldering smt. Making a fully open equivalent to the Beaglebone SoC is a nine figure endeavor at a minimum.
The reason you don’t see hobbyist x86 SBCs is that Intel and AMD make customers sign a large pile of NDAs before sharing the documents you’d need to make your own. And in the case of Intel, you need to pay a 3rd party to provide you with a BIOS framework that obfuscates the ME firmware and other blobs (like memory training) so that even the board manufacturer doesn’t have any idea what’s going on in those hidden processors. (source: used to help develop x86 server hardware)