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Comment by jacquesm | Hacker News Reader

> now Intel is fixing that

That's not a fix. That's a disabling. A fix repairs something.

If AVX-512 was not in scope yet left turned on, parts may operate outside design limits, there's system-level validation that may not have been run, and specs that are at risk. Think about the scale of all PC OEMs that use these CPUs, rather than a specific product.

For example, it's known that AVX-512 is power hungry and significantly increases TDP (heat). Do all Alder Lake based products have the thermal headroom? If CPUs operate outside of the envelope communicated by Intel, they may not be entirely stable, and parts could fail earlier than expected.

Bringing a product in line with specification is very much fixing it. Even if the fix happens to be disabling something.

There was no specification about this feature until immediately prior to launch.

When a company announces with years in advance a new product (e.g. Alder Lake), that is the replacement for their previous product (i.e. Rocket Lake & Tiger Lake) and in that series of products the most valuable feature is backward software compatibility and the new product will no longer have this feature, one would expect that the company should publicize vigorously the fact that the replacement product will not match the features of the replaced products.

Sure, but that's a customer expectation vs legal obligation.

Like, my sister bought the new M1 MacBook Air, only to discover that it doesn't support dual external screens - while her previous Air did. So there was absolutely an expectation there that any new MacBook Air would also support dual screens, right?

But, at the end of the day - it is mentioned in the spec sheet. She could have checked. Just assuming that a feature is there is not enough. What's more - if dual screens worked originally, and then they stopped working after an update - that wouldn't be a bait and switch either, it would be a fix to bring the computer back in line with its spec.

And yes, I agree that it would suck.

The difference is dual screens don't work on the M1 MBA because it physically only has two display controllers in the silicon, one of them wired to the internal panel, and the other muxed to the two TB ports. The M1 Pro has two external display controllers, and the M1 Max four. I can show you where they are on the die shots, and that it's not artificial crippling.

But what Intel is doing here is disabling existing silicon that exists and works.

Sure, but as a customer that's irrelevant, right? You had a MacBook Air, used it with two displays, then you buy a new MacBook Air and bam, it doesn't work with two displays. The technical nitty gritty is not really relevant - at least the comment I was replying to sounded this way. That what the customer expects is more important than what is on the spec sheet? The fact that previous Intel CPU supported AVX-512, and the new one doesn't - so whether this fact is or isn't mentioned in the spec sheet is not important, because what the customer expects should be ultimately what decides what is "ok".

Yes, but once it has shipped and people may have come to depend on it it will break stuff, not fix stuff.

Besides the obvious benefit of first having benchmarks out there claiming these chips are better than they really are. So this change just benefits Intel, and nobody else. If it would be a fix then it would be that something that was advertised did not work, and now it does.

>>Yes, but once it has shipped and people may have come to depend on it it will break stuff, not fix stuff.

If people depend on functionality that is explicitly unsupported then I don't know what to say other than that I don't see how that's Intel's responsibility. If you buy a CPU that doesn't support AVX-512 instructions in order to use AVX-512 instructions then ...I think you're the one who is wrong here.

To go back to my car analogy - if you buy a car that isn't type approved for towing, and yet you install a tow bar anyway, you can't complain to the manufacturer if stuff breaks.

>>Besides the obvious benefit of first having benchmarks out there claiming these chips are better than they really are

Are any of the published benchmarks using AVX-512 instructions that were used by Intel in advertising, and were those in fact available at the time when the benchmarks were ran?

>>If it would be a fix then it would be that something that was advertised did not work, and now it does

Those CPUs were not compliant with their own published spec, now they are - it is absolutely a fix.

> Yes, but once it has shipped and people may have come to depend on it it will break stuff, not fix stuff.

That may apply to every change, including things everybody agrees on to be bug fixes. If, for example, you improve the number of correctly returned bits for computing sin, that can break programs, for example games that want to keep world models in exact sync across systems.

From what I read here, intel didn’t advertise this feature and it wasn’t easily discovered. If so, I don’t think customers have any claim against Intel for the CPUs.

_If_ motherboard vendors advertised/promoted it (could be as simple as blogging about it), I would think people who bought a motherboard because it allows activating this feature will have a case against them (in the EU and possibly elsewhere, the seller is responsible for the product being fit for purpose, not the manufacturer, so it would be the seller, but let’s ignore that)

Legally, there also is the issue who applies that update. From what I read, that’s the motherboard. Here again, I would say that, if customers have a case, it would be against whomever sold them the motherboard (e.g. if that silently applies the update) I don’t see any indication that Intel, as a CPU manufacturer, forces existing customers to install this.

To add to this - even if the motherboard manufacturer allows this despite Intel's advice, in their stock configuration none of those CPUs allow AVX-512 instructions out of the box. You need to knowingly and conciously go into the BIOS and disable all efficiency cores first, to make this option even appear. So "as sold" the product doesn't support AVX-512 instructions and the advertising is absolutely correct. Just like you can overclock the CPU but it doesn't come overclocked out of the box(and Intel assumes no liability if you do overclock it).

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