arm-trusted-firmware VS darwin-xnu

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

Here's the C source code of the font itself, as a 256x16 array of 8 bit values.

> Update: fortunately there's still Mac OS.

Go download the source for Darwin.. https://github.com/apple/darwin-xnu

Compile it. Install it on your MacBook. Tell us how well MacOS boots that kernel.

What is still true? That apple kernels are Mach kernels? It still is very true. Darwin is (mostly) open source, you can check it out here: https://github.com/apple/darwin-xnu

Everything that includes copyleft code is open source. You can see https://opensource.apple.com for a full list

Jup! Their kernel was based on FreeBSD, IIRC, and is Open Source!

Funfact darwin itself is open source aswell: apple/darwin-xnu: The Darwin Kernel (mirror). This repository is a pure mirror and contributions are currently not accepted via pull-requests, please submit your contributions via https://developer.apple.com/bug-reporting/ (github.com)