Pixel Background Data

fps

I have concerns about using a pixel and these concerns may be wrong.

With the pixel, the battery can't be removed from the phone. Also, even if the phone battery is off, many motherboards have batteries on them that are different from the phone battery.

Does the circuit board of the phone allow any hardware access to the cellular modem in the absence of software?

So here's an example of something that wouldn't be able to access the modem without software:

Hardware-----

Hardware----- ----> All data gets sent to chip that can't function without software ---> Cellular modem

Hardware-----

Here's an example of hardware that could access the cellular modem even if software doesn't allow it:

Hardware <-------------------------------->modem
(camera) ^
^ -

-

-

*
CPU<------------------------------------------>software

*should be down arrow thing

i don't know how to make the graph look normal. the first one should have cpu in between hardware and modem

the second should be a box and hardware can access modem from hardware like camera to modem or from software to cpu

In example one, hardware has no direct electronic connection to the modem and in example two, it does have direct access both by connecting to the CPU and then software but also by connecting directly.

This is probably a bad example and I'm not a circuit designer, so please don't accuse me of spreading misinformation, because I am not claiming this and instead just posing a question. This is a very bad diagram to present my lack of understanding

Because I can never take the battery out, and I have no access to what the modem is doing, I can't measure if the modem is sending data while inactive and that scares me. I also can't ever even pull the battery out to be less scared about that when I am not using the phone.

I know there are such things as faraday bags but those are expensive bulky and not always reliable from what others have said.

Although I know Graphene is open-source and trust that it's good software, I don't understand if the software prevents other parts of the hardware from communicating with each other based on the firmware code for the hardware itself. It's possible someone more knowledgeable could say definitely it could or couldn't.

de0u

fps Because I can never take the battery out, and I have no access to what the modem is doing, I can't measure if the modem is sending data while inactive and that scares me.

At the end of the day, if the cellular modem is "sending data", the radio signal must be detectable for the data to get anywhere. Equipment to reliably detect and decode cellular-band transmissions is expensive, but a university lab near you may have some, likewise some repair shops.

fps I still don't feel safe since I don't understand how the hardware can or can't access the modem in the absence of software.

Which hardware? I think your diagram suggested the camera might "access the modem", but the camera does not contain an evil spirit that can reach out to things on the motherboard. The camera is managed by software in the OS. If there is hardware that could be thought of as having a mind of its own, the cellular modem would be a better candidate... when it isn't powered off.

Overall I think your options may involve:

Reading a lot about SoC architecture and phone design, so you can form an educated opinion, or
Picking an expert, asking whether a particular threat scenario is plausible, and then trusting the answer.

Because it does not appear that reading posts on this forum has provided information you find trustworthy, it is not clear how posting here (as opposed to locating an expert offline) will help.

I encourage you to determine what sort of expert will provide an answer you can trust. Otherwise there is a risk of asking many people in many forums, and being told that a scenario is not a plausible risk, but never trusting the answer (even if it is accurate).

GrapheneOS

fps In general, removing the main battery from a device does not prevent hardware from continuing to run in a low power mode via capacitors or small batteries.

Cellular modems in the supported devices do not have special privileged access beyond other radios and the idea that the way they function or are integrated is fundamentally different from Wi-Fi, Bluetooth, etc. is fundamentally wrong.

Your paragraph with false claims about how we moderate the forum where you promoted non-hardened operating systems drawing a false equivalence to GrapheneOS has been removed. Continue down that path and you'll be suspended. We chose to remove only that paragraph rather than the whole post, despite direct violations of the community rules.