rpi4-osdev VS Raspberry_Pi4-B_Assembler

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.

You can do them both, i.e., write assembly code that runs on a bare metal Pi with no OS. Your code may have to do a lot of work, because it will need to take care of anything the OS would, like interacting with any of the Pi's hardware systems. See: GitHub - kernm/Raspberry_Pi4-B_Assembler: How to code Bare Metal with Assembly language for a guide.