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Comment by ZiiS | Hacker News Reader

If it can be silently removed was it a security feature?

Whilst I hate companies paying engineers to make things worse just to segment their market; I am not really seeing this as an important feature outside the data-center? If an evil-maid has hardware access they hack the USB and/or PCI not the RAM surely?

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Sneakily and silently removing a feature in a firmware revision is not acceptable, security or otherwise.

if anyone does it sneakily, there is alleged wrongdoing attached to it. I can imagine multiple scenarios like some well-known Israeli company "selling their software only to governments", paying quite amount of money for it, because they were unable to break this one.

> there is alleged wrongdoing attached to it

Probably not from a legal perspective, but morally yes. Apple cause batterygate with good intentions but sneakily. Not being transparent is what shot them in the foot. AMD didn't learn anything or thinks this is small-time so no blowback (sadly they might be right).

> Apple cause batterygate with good intentions but sneakily.

Sure, the Apple's intentional performance degradation of older iPhones was caused by only good intentions, not a form of planned obsolescence in any way. How could it be?

If you ever had to use an iPhone that would just shut off randomly with like 30% battery "remaining", you'd probably be singing a different tune and appreciative your device became somewhat more usable with the changes.

I'd expect the battery charge estimation to be recalibrated to account for the reduced capacity, not the hardware being deliberately hobbled to hide it.

I heard the old batteries, when giving high current would depress voltage long enought to trigger the shutdown, plausibly long enough to mess up the processor if it didn't shut down, but could genuinely give a lower current for a long time, such that rounding the charge down to zero would be harmful. It's easy to argue it's better to keep the phone slower then just shut it down when it can't reliably go fast.

But it’s not a matter of total charge, but output, hence it shutting down even though there’s plenty of stored energy in the battery.

Aging or damaged batteries can have dramatic'ly different output curves than the system expects. What looks like x% to the system can be at the edge of a cliff on the curve, causing sudden shutdowns or power loss.

> Sneakily and silently removing a feature in a firmware revision is not acceptable

What if said feature was sneakily and silently added in the first place? Wouldn't it be acceptable to sneakily and silently removing it in the future then? Or regardless of if it was documented/announced or not, removing anything sneakily and silently is bad?

Yes, silently slipping in changes to capabilities during a firmware update is never okay. In the hypothetical where that happened inadvertently and now needs to be reverted that corrective action needs to be just as noisy as any new feature would be.

Removing it required AMD's firmware code signing keys. If an attacker has those and some time they can do much worse.

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