Custom OS

[MaskOfLoki]

I'm going to be buying a Pinebook here soon, and I was curious if it's possible to run a custom OS I've written on it. Specifically, does the booting partition have to be FAT32, or does it allow for custom bootloaders and such?

Sorry if this isn't the correct section to post this.

[xalius]

No boot partition can be whatever you like, you don't even need one really... the only things you need to make a medium bootable is the second stage loader (either binary boot0 for legacy kernel or spl for mainline u-boot built from souce) and u-boot. Once u-boot is loaded you can boot whatever you want from any media u-boot can access/has drivers for...

[MaskOfLoki]

Dang it. I was hoping I wouldn't need to write a driver for anything. Was kinda hoping I could use my own self-coded bootloader that comes with my OS. I guess I won't be using the Pinebook then

[z4v4l]

Dang it. I was hoping I wouldn't need to write a driver for anything. Was kinda hoping I could use my own self-coded bootloader that comes with my OS. I guess I won't be using the Pinebook then

That's funny. How did you write your "custom" OS for it then? Did you test or write it without testing?
If you don't wish to use u-boot, you can replace it with your "self-coded" bootloader. Just expose it for Boot ROM code the way it expects.
Admit it, your OS does exist only in your fantasies yet?

[MaskOfLoki]

I've got one that I've written on the Raspberry Pi, and I wanted to find a Prebuilt ARM computer I could port it over to.

[MaskOfLoki]

Also, why would it matter if my OS was written or not? That has nothing to do with the subject matter.
Anyways, I thought uboot was stored on the board in the ROM. Was I incorrect in assuming that?

[xalius]

The first stage loader is part of the SoC (BROM) and is fixed, the SPL (second stage loader) and u-boot are on your boot medium, you can replace those with whatever you want. If you don't use u-boot's SPL and the ARM trusted platform firmware you have to do the whole initialization of DRAM, CPU cores and power management yourself. Have you looked at the A64 user manual and read up on the low level boot process? https://github.com/apritzel/pine64/blob/...Booting.md

[z4v4l]

Also, why would it matter if my OS was written or not? That has nothing to do with the subject matter.
Anyways, I thought uboot was stored on the board in the ROM. Was I incorrect in assuming that?

It has. Because if one "has written OS", he/she probably already knows about the platform far beyond that trivial thing as "what partition to boot from has to be there". Because you asked this question, I was wondering.
and this sentence is just brilliant, to not wonder:

and I was curious if it's possible to run a custom OS I've written on it

Don't get pissed off, it was a friendly irony, I wish you success with your OS, you "have written". OSDev is my passion too. That was actually why I reacted. Btw, I also "have written" firmware for Pine64, UEFI compliant (in fact I am sitting and trying to implement AllocatePages() Boot Service routine right now), so you might consider using it for your OS. In future, when our fantasies will mature into reality a little.

[MaskOfLoki]

xalius, thank you for your help. I'll look over that document.

z4v4l, you're using irony wrong. And I won't be using your firmware since mine is part of my research project/paper.

Won't be back till I've got everything ported over, and once I've got graphics going.