That's not a valid reason why I can't use them on the P cores. Some motherboards can enable them on the i9-12900k, it works fine, but you need to pin to a P core.
The reason is that it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit to shipping everything with AVX-512 support in future steppings/revisions.
If you disable E cores you could enable AVX-512 on certain motherboards, but like I said that’s not really a net win 99.99% of the time when you’re giving up entire cores.
It was also at your own risk because presumably the power/clock speed profiles were never tuned for a feature that wasn’t actually supported. I can see exactly why they turned it off on newer CPUs only after an announcement.
Still smells like bullshit. Let the customer decide. Who cares if it was validated? Why was it even included? Just put it behind a yes-I-really-mean-it-switch so nobody uses it by accident.
Several motherboard vendors added that very switch in UEFI (some even with the option to force an older microcode version AFAIK) before it was disabled in hardware by Intel
> it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit
Only because they screwed it up on purpose! That's not an acceptable reason for removing the feature; in part because it would apply to any feature they decided to cut.
If you disable E cores you could enable AVX-512 on certain motherboards, but like I said that’s not really a net win 99.99% of the time when you’re giving up entire cores.
It was also at your own risk because presumably the power/clock speed profiles were never tuned for a feature that wasn’t actually supported. I can see exactly why they turned it off on newer CPUs only after an announcement.