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Comment by mcintyre1994 | Hacker News Reader

mcintyre1994·

Do the cameras/microphones need to be controlled by the baseband? Naively they seem like they should be at a slightly higher level than the main radios, and should be controlled exclusively by the OS. I'm guessing from your comment there's some reason that's not the case though?

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In addition to the basebandy RF stuff that you expect the baseband to do, it also does real-time voice modulation and call quality things like echo and noise cancellation… things that high level OS would do too slowly.

In 2023 I suspect this is less and less necessary- apple silicon is very fast and a lot of voice comms goes through an app (FaceTime?) anyway but … I’m sure those capabilities are still in the baseband processor …

There is this [0] thread from a few years ago. According to the linked article, "unless an IOMMU is used, the baseband has full access to main memory, and can compromise it arbitrarily." No idea how true this statement is.

0: https://news.ycombinator.com/item?id=10905643

Tough to say, information about the systems is restricted and hard to come by.

I'm pretty sure they have hooks into audio systems for wireless emergency alerts, but could be wrong.

The microphone does need to be connected to the phone. Not so much the camera.

Does it? The OS must be able to send audio to the phone modem (bluetooth, homepod, etc), so it seems reasonable to me that it wouldn't have direct access to the microphone and that would go via OS also.

Not in theory, but certainly historically. Last I read, there was still an AT command channel present. Some of that IP is super old.

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