arm-trusted-firmware VS subsurface

I have a PinePhone Pro, and I'm trying to figure out a reasonable way to get more than one half of ten minutes of battery life out of it, while still receiving notifications. I figure the best route to go will be to create a service that holds ports open, while the CPU is completely asleep, and either run it on the modem's processor or, as an possibility for the PinePhone Pro, but not the original Pinephone, run it on the m0 core used for power management.

Arm v7 was a Wild West, but with v8, Arm tried to standardize a lot. The Arm Trusted Firmware is the reference boot firmware implementation for v8+ CPUs: https://github.com/ARM-software/arm-trusted-firmware.

I'd think most of the referece documents can be discovered from that code base.

Relatedly, from the perspective of hands-on programming, the System Programmer's guide is the manual to start with.

I assure you that there is no lack of skill; that is just what happens over the course of ten years in a 300,000 line code-base and multiple hundreds of contributors: https://github.com/ARM-software/arm-trusted-firmware/blob/master/Makefile

The ARM Trusted Firmware is what typically runs in the secure world, and it is indeed open source: https://github.com/ARM-software/arm-trusted-firmware

ROM code generally speaking is not open source, but has been dumped on occasion.

The reference Trustzone implementation for ARM is open source https://github.com/ARM-software/arm-trusted-firmware , so I really can't think of some reason the ARM license would have to do with it.

SMP support (at least as far as CPU suspend and hotplug goes) is usually handled by TrustZone firmware on aarch64, not by the kernel (see PSCI). If you write your own OS on a bare-metal platform you can of course do what you want, but if you're looking for existing sources that's where you'd have to look. https://github.com/ARM-software/arm-trusted-firmware is a common reference implementation that supports a bunch of platforms, but many others (e.g. all Samsung and Qualcomm phones) also use their own proprietary stuff which is not publicly available.

Come again? https://github.com/ARM-software/arm-trusted-firmware

why would you think he doesn't use other apps? Heck, he even wrote this https://github.com/subsurface/subsurface , although now other folks maintain it.

Also Subsurface Dive Log

Do you mean Subsurface?

> From the words of Linus himself

Since you don’t cite the source, I will assume that you’re referring to the Subsurface documentation (https://subsurface.github.io/download/). Linus himself, however, did not write it: https://github.com/subsurface/subsurface.github.io/commit/91...

So true, where would we be without Subsurface ?

Coincidentally, Linus Torvalds took a sabbatical to make a dive log program. https://subsurface-divelog.org/

He's actually very pragmatic & uses C++ too when he likes the framework using C++ better. https://github.com/subsurface/subsurface

That didn't stop him from making a pet project in C++: https://subsurface-divelog.org/ I'd say that if he seriously didn't like it, he'd have used C or something else.