Comment by jandrese
7 years ago
Hard to imagine that the SoC is still being dumped after all of these years, if it even was in the first place.
If the purpose was to kill off the grossly overpriced PC104 market, mission accomplished. The fact that those boards have spawned a zillion competitors seems to suggest that any further dumping is not having the desired effect.
A free ISA is about more than saving a few pennies on each board in royalties, it's about having a chip you can truly trust. One that doesn't have some opaque binary blob running at ring -2. One where nothing is encrypted by a key only the manufacturer (and whomever they can strike a deal with) has. About hardware you truly own and control.
As much as I believe that RISC-V will work its up in the embedded space, I don't think many people care about the "chips you can truly trust" argument.
The moment you're talking ASIC (or even FPGA, with an opaque bitstream), it's anybody'd guess what happens whether you use a RISC-V CPU or not. Even if the known CPU is known to be untainted, a tiny, invisible, additional CPU is sufficient to take over the chip and you'd be none the wiser. The area cost of such an additional CPU would be essentially undetectable, less than 0.01mm2 on a modern process.
Unless you're talking about making your ASIC, but in that case, a commercial offering (which typically comes with a source code license) gives you just as much access to review the code for hidden firmware.
Given the possibility of dopant-level backdoors (see https://sharps.org/wp-content/uploads/BECKER-CHES.pdf ), you can't trust a chip you didn't fab yourself even if it passes optical inspection.
But maybe a simple FPGA design would be resistant to this technique if the attacker didn't know the intended bitstream in advance.
> A free ISA is about more than saving a few pennies on each board in royalties, it's about having a chip you can truly trust. One that doesn't have some opaque binary blob running at ring -2. One where nothing is encrypted by a key only the manufacturer (and whomever they can strike a deal with) has. About hardware you truly own and control.
This has basically nothing to do with the ISA. It's not the ISA that hides secrets and requires binary blobs. A chip is much more than an instruction set, hence why dealing with the proprietary undocumented garbage to bring up a new ARM SoC is a pain in the ass even if you've memorized every ARM instruction down to its encoding...
If RISC-V gets picked up and used by mainstream chipmakers in the SBC & TV BOX & mobile space, there is no doubt we will end up with chips that have proprietary undocumented garbage interfaces. Just like they also now take something like the (open source) ATF or OP-TEE, implement support for their own chip, and then publish a binary blob without source code.
IIRC, the original RasPi SoC was intended for a Nokia smartphone that was cancelled
The original RPi SoC was intended for DVRs and set-top-boxes and maybe as application CPU in midrange TVs. The design with huge-ish video accelerator and highly battery unfriendly power requirements is totally unappropriate for anything mobile, even less for anything designed by Nokia with their full-custom PMICs with internal ARM cores and so o on...
I thought it was for set-top-boxes; that's why it's mostly video decode with a small ARM to run the menus.
Yup. Some models of Roku apparently even shipped with the SoC used in the original Raspberry Pi.
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it's about having a chip you can truly trust
This gets repeated over and over but I don't get it. You could build a blob-free ARM chip. Existing RISC-V chips already have/had blobs. Freeeeedom is orthogonal to the ISA.
I guess with a royalty-free ISA the chips themselves are a bit more likely to be open source? SiFive has a lot of HDL (Chisel) code on their GitHub. I can find at least the I/O blocks: https://github.com/sifive/sifive-blocks/tree/master/src/main...