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Comment by eksith | Hacker News Reader

Suddenly, everything I've done thus far seems rather inadequate. However, kudos for doing this! I hope you haven't stopped working on it.

Looks like you've worked on the expected base functionality.

https://github.com/SamyPesse/devos/blob/master/kernel/arch/x...

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Never too late. The only problem with writing an OS is that you are exposed to the x86 architecture - which is HORRIFIC, but even something as small as booting to "hello world" gives you a wealth of knowledge about the underlying layers that we take foregranted.

'Foregranted' should be a word, I like it.

Targeting ARM and using qemu is a good way to stay out of x86 land.

I'm not really qualified to say, but isn't modern ARM also quite horrific from osdev point of view. At least x86 has some sort of standards imposed by intel, but with ARM every manufacturer is doing it's own thing with the peripheral functions. Wasn't that what Linus was complaining some time back that Linux ARM support files are blowing up because there is too little code shared between platforms?

That's only an issue if you're building a general purpose OS that tries to target every ARM board out there. If you're just making a hobby OS on a simple device, then you don't really need to worry about it. In the x86 world it would be analogous to saying that you don't need to worry about writing an ACPI engine into your hobby OS.

The main issue I've encountered is actually finding documentation for these various architecture-specific oddities.

I looked at the teaching kernels xv6 from MIT, and Pintos from Stanford. They are both x86, and I've heard the same sentiment that you express, which makes me a bit hesitant to dive in.

Does anyone know of something similar for x64? Or maybe ARM? Online course materials would be nice.

http://www.stanford.edu/class/cs140/projects/pintos/pintos.h...

http://pdos.csail.mit.edu/6.828/2012/xv6.html

I doubt x64 would be less horrific. As for ARM, there is Cambridge's Baking Pi course http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/, which has you develop an "Operating System" for the Raspberry Pi. Although, from looking at it, it seems more like an embedded systems course than an OS course. It talks about controlling hardware like LEDs, monitor, and keyboard, but it doesn't talk about stuff that full-fledged operating systems have, like scheduling of userspace processes, memory mapping, filesystems, etc.

My own effort from late in high school:

http://glider-kernel.sourceforge.net/

Unfortunately, I'm not allowed to put my 236376 Operating Systems Engineering course project online, due to the licensing issues with JOS-based project code.

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