i don't think the manufacturers would share what arch their deeply embedded cores are. Christopher Domas was the first person to interact with what he calls ring -4 to escalate from ring 3 to ring 0. the processors were old, and the ring -4 is not x86. I'm looking at a slide from 2019 that says that IME is a physically separate, non-x86 processor that boots minix
Now, i may be misremembering and i don't have time today to download all his talks and grep the .vtt for "ARM"; however, my memory is reinforced by literally 30 seconds of internet searches. i bought the Minix book because of one of the presentations.
i'm not doing any more research for free on this. Even if it isn't ARM, it isn't x86.
fine, you win. every bit of the CPU in an intel CPU is 100% x86. nevermind that the thing i am talking about is more "deeply embedded" than the management engine, has access to all registers, etc. oh and is specified to be RISC. I guess technically x86 is RISC, so...
preface: you brought up IME which isn't what i was talking about. that's ring -3. The thing i am talking about is either adjacent or "above" that in the hierarchy. I was not, and never spoke of the ME. i quoted the "physically separate" part for a reason, although if prodded, i couldn't have told you at the time. it isn't on the CPU die. anyhow:
It's funny that i knew about the minix even though according to your sources that wasn't what was running on the x86 chips until after they removed the RISC embedded cpu and switched to "x86." i've looked at your wiki link and followed the footnote, to an archive.org page where it is merely claimed that it is "now x86" and "running minix 3".
So we're at an impasse. I'm not downloading a bunch of youtube .vtt files and you've linked as authoritative sources as i have at this point; "someone said so."
that is: wiki cites the ptsecurity blogpost from august 2017 as the source for the claim that it is x86. furthermore, the blogpost claims that the architecture is "lakemont" which is 32nm, but the blog claims it's 22nm. Further, it claims it's specifically the quark, which was discontinued in 2019. i understand they can use the IP in the toolchain to put that on the main die, as well as build that part of the die at a larger size. However, there are a few other assertions that appear in there (in the code listings) that appear nowhere else on the internet.
oh, and ask mister occam if a physically separate chip (the Intel PCH 100 and up) counts as "embedded in the intel CPU" which is what i've been saying (ring -1, ring -4 are all on the physical die of the CPU.)
Now, i may be misremembering and i don't have time today to download all his talks and grep the .vtt for "ARM"; however, my memory is reinforced by literally 30 seconds of internet searches. i bought the Minix book because of one of the presentations.
i'm not doing any more research for free on this. Even if it isn't ARM, it isn't x86.