yes, not a unix os but rather unix-like, and i want to program all of it on python, is that possible?? even the kernel, i want it all python. i know most kernels use c++ or c* but maybe python has a library to turn c* into python?? i’m still sort of a beginner but thanks and i would appreciate the answers
As it happens, this is strikingly similar to an interview question I sometimes ask: what parts of a multitasking OS cannot be written wholly in C. As one might expect, the question is intentionally open-ended so as to query a candidate’s understanding of the capabilities and limitations of the C language. Your question asks about Python, but I posit that some OS requirement which a low-level language like C cannot accomplish would be equally intractable for Python.
Cutting straight to the chase, C is insufficient for initializing the stack pointer. Sure, C itself might not technically require a working stack, but a multitasking operating system written in C must have a stack by the time it starts running user code. So most will do that initialization much earlier, so that the OS’s startup functions can utilize the stack.
Thjs is normally done by the bootloader code, which is typically written in assembly and runs when the CPU is taken out of reset, and then will jump into the OS’s C code. The C functions will allocate local variables on the stack, and everything will work just fine, even rewriting the stack pointer using intrinsics to cause a context switch (although this code is often – but not always – written in assembly too).
The crux of the issue is that the initial value of the stack pointer cannot be set using C code. Some hardware like the Cortex M0 family will initialize the stack pointer register by copying the value from 0x00 in program memory, but that doesn’t change the fact that C cannot set the stack pointer on its own, because invoking a C function may require a working stack in the first place.
In Python, I think it would be much the same: how could Python itself initialize the stack pointer necessary to start running Python code? You would need a hardware mechanism like with the Cortex M0 to overcome this same problem.
The reason the Cortex M0 added that feature is precisely to enable developers to never be forced to write assembly for that architecture. They can if they want to, but the architecture was designed to be developed with C exclusively, including interrupt handlers.
If you have hardware that natively executes Python bytecode, then your OS could work. But for x86 platforms or most other targets, I don’t think an all-Python, no-assembly OS is possible.