I can't even begin to imagine the kind of corporate dysfunction that leads to, first, at long last introducing the biggest change in the instruction set since the Haswell era into the consumer CPU line, slowly getting some actual adoption on that, and then suddenly dropping it altogether (for rather dubious reasons), but actually not really, so random motherboard vendors get to re-enable it behind your back.
This is crazy, both in terms of CPU design and just basic communication. Personally, I'll be waiting out this generation until I see AMD's response. Taking AVX-512 seriously is even harder than it already was.
You all would probably find the "QuickIA Software Support" section interesting, they go through a few issues you run into when you have incompatible micro architectures running in a single system. It also might help illuminate where Intel's head was at during the early research phase of creating a heterogeneous processor.
I decided to search for SMP, which stands for Symetric Multi Processing, to verify its definition. This acronym is used for hardware sporting several identical CPUs, which is what we've seen so far in the x86 world.
The opposite is called AMP, for Asymetric Multi Processing. The Wikipedia article on the subject describes several OS level strategies to handle that sort of hardware.
If the processor faults for an invalid instruction, it can simply trigger a migration to another core. The OS should be able to do it.
Even if it's randomly assigned to a different core, eventually the process will end up on a good one.
So Intel is chasing AMD...But AMD is actually chasing Apple now. So Intel has two frogs to jump this time.
AMD has a real opportunity at long term strategic victory in computing. If they can be the leader in a mass shift of the Windows/PC ecosystem in an ISA change to ARM then Intel might be toast.
Let's say AMD gets a near-M1 chip out quickly with the same gee-whiz battery life out 18 months before Intel, and can produce them at a cost the Intel's business people sniff at because they are so fat on margins, even now.
And servers and laptops swarm the market such that it becomes an inevitability that mainstream PC/Servers will go ARM as the dominant ISA.
Intel will be in deep trouble.
It also would be an opportunity for Apple to dominate the PC market with OSX by making a more general-hardware OS, but they won't do that.
And of course it is YET ANOTHER opportunity by desktop Linux to gain a foothold, but at this point it's more likely that Android or an evolved Windows-that-is-99% linux becomes that.
A lead over AMD is one thing, but the M1 is a mobile CPU and this is a desktop one.