rpi4-osdev VS circle

GitHub - isometimes/rpi4-osdev: Tutorial: Writing a "bare metal" operating system for Raspberry Pi 4

Basically i can compile and run this -> https://github.com/isometimes/rpi4-osdev/tree/master/part5-framebuffer (and i'm sure every other implementation) just fine but only if i load it with gdb through jtags and then hit continue (c). If i put the exact same kernel (kernel8.img) on the sd and disconnect any hw debugger, it gets stuck at the rainbow spash screen and won't continue. This is wheter enable_jtag_gpio is set to 0 or 1. This makes absolutely no sense to me and i'd love to get an opinion on why it behaves this way and if it underlines a bigger problem.

Something like this would be probably in the top 1% of hobby projects and as far as I can tell, it involves zero EE work: Writing a "bare metal" operating system for Raspberry Pi 4.

This might be of help: https://github.com/isometimes/rpi4-osdev (it’s for the RPi4, but I imagine most of it being applicable to the RPi1).

IMO the best way to get into this type of low-level tinkering is by writing a simple operating system.

https://github.com/isometimes/rpi4-osdev

There are other courses/projects for other boards. The keyword is usually “baremetal”.

For Linux drivers specifically there are training material from Bootlin for instance.

If you're a developer and feeling adventurous, you can also try building it yourself. The source is all on GitHub. It uses the circle-stdlib project (which is circle plus some additions to support much of the C and C++ standard libraries) as a submodule; hopefully I've set that up correctly, but you could always clone that separately and place it in the MiniScript-Pi folder. Check out circle's build instructions for info on setting up your toolchain. (Mac users: be careful with the configure script, which does not work properly on MacOS; find me on Discord and I'll help you fix the script or configure manually.)

I suggest checking out circle https://github.com/rsta2/circle since it's basically a library for the pi hardware. I'm doing some experiments with it myself now.

You can also run a Pi without an operating system, programming it in C or C++ probably. See for example: GitHub - rsta2/circle: A C++ bare metal environment for Raspberry Pi with USB (32 and 64 bit)

BMC64 is VICE in a trenchcoat unikernel / bare-metal framework called Circle: https://github.com/rsta2/circle

It uses the circle library (https://github.com/rsta2/circle) to provide a minimal runtime (mainly to interface with the hardware).

I experimented with circle the other day (https://github.com/rsta2/circle) Looks promising, and most likely within your knowledge of C/C++ development.

Natively would be amazing but a vast amount of work.

The way Apple moved classic MacOS from 680x0 to PowerPC was to write a tiny kernel emulator, with an API to run native stuff on the metal, and run more or less the whole OS under emulation, profile it and just translate the most speed-critical bits.

That's a lot of work for a FOSS project but given the performance delta between 1980s 680x0 and 2020s ARM, total emulation of the whole thing should be perfectly fine. It's how the PiStorm Amiga upgrade works.

https://amigastore.eu/853-pistorm.html

So all I envision is something like Aranym:

https://aranym.github.io/

... running on top of Ultibo, say:

https://ultibo.org/

Or maybe Circle:

https://github.com/rsta2/circle

Circle is a C++ bare metal programming environment for the Raspberry Pi.

The only other reasonable option would be to port it to a new platform which is popular that has a few well documented hardware interfaces so as not to create a hellish nightmare writing drivers. Maybe then you could do a one-off port to that platform (though you might have to re-target the HolyC compiler to target it instead if it is not x86_64). The Raspberry PI seems like a decent option here since there is already a baremetal C++ library supporting USB, keyboard, mouse, sound, video, and as an added bonus UART, I2C, SPI, GPIO. You would have good code examples for porting all the necessary drivers. But obviously this would still be a lot of work and the compiler would need to be re-targeted and user space adapted for running on ARM. That being said backwards compatibility is strong, ARM seems actually interested in keeping it that way (at least for now). The library I'm talking about is here: https://github.com/rsta2/circle