> If your Linux laptop doubles as a music player, another nice new feature is that you can now stream your audio over USB even while the rest of your system is asleep. That capability's been available in Android for a while, but now it's part of mainline Linux.

I thought Android did that by just turning off all but one CPU core and suspend all processes not required for streaming + bluetooth?

I really can't imagine how else that would work, other than essentially giving the whole audio file to the Bluetooth chip and let it handle streaming on its own... but I've never heard of a Bluetooth chipset capable of that, much less bluez actually being usable enough.

Since sleep suspends execution and keeps the RAM state, I suppose it isn't a huge stretch for the kernel to provide some mechanism by which a program can stay awake while execution of others is paused.

I'm sure there are aspects that are hard to reason about which I'm simply unaware of, but the idea makes sense to me.

It hands it off to a dedicated media playback DSP. Right now, only Qualcomm is supported but there’s hope that now that the mainline kernel supports it other hardware providers will offer a way the kernel can do that for them, too.

On modern Intel systems sleep works the same as on android. You don't just ask the chipset for s3 anymore.

I wouldn't be surprised if one core stayed awake.

This is why tiger lake laptops had crummy battery life on Linux upon release (often on windows too). Without working s0ix they just never suspend, and old style s3 isn't really officially supported.