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0 pointsPragmaticPulp4y ago0 comments

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.

0 comments

R0b0t14y ago

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.

kadoban4y ago

There's not many great places for such a switch, and even then, then you have to validate _that_ behavior. It's mostly just not worth it.

pantalaimon4y ago

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

Dylan168074y ago

> 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.

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