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In my research on phones from the Unrevoked project (admittedly, 4+ years ago), this was the case: the baseband and the CPU shared the same memory. The baseban
by jwise0 11y ago
In my research on phones from the Unrevoked project (admittedly, 4+ years ago), this was the case: the baseband and the CPU shared the same memory. The baseband memory was carved out from the CPU such that the CPU could not access it, but the microcontrollers serving the baseband had CPU access, as I recall from the Qualcomm boot documentation: the chain of trust from CPU boot was established by the baseband processor, not the other way around.
I would imagine that things have changed a little bit, but the baseband back then, and I imagine still now, is considered to be the ultimately trusted element of the system. I'd be surprised to hear that they've changed so much that the baseband doesn't still have full control over its host system.
- BillinghamJ 11y agoBear in mind that the baseband's host system doesn't necessarily need to be the same as the phone's core systems. You could just isolate the baseband and only communicate with it via a defined interface.
- tptacek 11y agoThe baseband doesn't have full control over phone systems.
- throwaway7767 11y agoYou should qualify which specific phone designs you are referring to (or if it's "all new phones", when the cutoff date was). After all, you are responding to someone who has researched this and found (like others) that indeed, the baseband in older phones did have full control. Your statement is general to the point of misinformation.