Sure it helps but does it _have_ to be on a separate chip? In ye olden days when everything else had crashed and was frozen, skype calls still kept working

Historically, it's generally been cheaper and easier to have two chips than to persuade a consumer or server OS to provide reliable time guarantees.

Hypervisors like that already exist and are needed by cloud providers.

Well, even in that context you have AWS for example doing control plane operations on a different SoC - https://docs.aws.amazon.com/whitepapers/latest/security-desi...

I think it's more the fact that the M2 chip is used across multiple product lines that don't need the unique capabilities of the R1 chip.

I think it makes sense. The parts of the system that need to respond within certain time windows because of physics run in the R1 (presumably, “realtime 1”). Everything else is just an iPad, which currently runs on the M2.

Valve Index is similiar. I've had my whole desktop freeze but the spatial orientation is still drawing within the VR as the headset is moving albiet in a frozen state.

The Valve Index does not do reprojection on the device. It does not even do tracking on the device.

It does it on the PC?

SteamVR’s tracking page[1] explains it a little. The HMD is really just displays, radios to talk the controllers (standalone trackers will just have a dongle, runs the same firmware iirc), and its own chip to talk to its own tracking sensors. All the tracking stuff amounts to timing information which is screamed over USB to the PC which does all the math to figure out where you are.

A bulk of this (really interesting!) information can be found on their HDK documentation, but that requires you to sign up with Steamworks.

[1]: https://partner.steamgames.com/vrlicensing

Yes, the runtime handles interpreting the sensor data collected by the device to compute the position and orientation they are in space. The compositor will reproject the next frame it sends to the headset if the application producing the frames does not submit frames before the deadline.

Yep, R1 chip.