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Comment by phendrenad2 | Hacker News Reader

> the “tinkering” part is a small thing that makes all the difference when one is first led up to a computer

True, but when making an OS, assembly code is an incredibly small part of it. You basically need to run a few instructions to put the processor in the right mode, and you need ONE line of assembly code (often inline C) to allow usermode to call supervisor mode. When choosing an architecture for a learning OS, I think other factors would dominate, like availability of hardware (many people have a PC already, saving them $100-$200 on RISC-V hardware).

> right… and if you ignore it, maybe it’ll go away. like Intel Management Engine, perhaps. Which OS does it run, if you know? :)

I'm not interested in gatekeeping tech to only those who care about personal privacy, so I consider this line of thought completely irrelevant to the discussion. But that's just me...

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> True, but when making an OS, assembly code is an incredibly small part of it.

A few comments up this thread i briefly mentioned r/xv6 entry.S, so here’s what i meant:

rv64:

https://github.com/mit-pdos/xv6-riscv/blob/riscv/kernel/entr...

amd64:

https://github.com/dancrossnyc/rxv64/blob/main/kernel/src/en...

> You basically need to run a few instructions to put the processor in the right mode, and you need ONE line of assembly code (often inline C) to allow usermode to call supervisor mode.

Right… Please see above. Also, in riscv land we have machine, supervisor and user modes, with hypervisor mode being in the works.

> When choosing an architecture for a learning OS, I think other factors would dominate, like availability of hardware (many people have a PC already, saving them $100-$200 on RISC-V hardware).

yet, MIT PDOS thinks Fabrice Bellard’s ubiquitous qemu is a better, cheaper and more forgiving starting point, although i personally prefer to spend a few bucks on something as absurdly cheap and cool as kendryte k210/k510 SoC and enjoy the real deal.

> Intel hate keeping tech is irrelevant [I don’t care]

Yes, it’s just you. Also, it runs Minix.

Cool links and all, but can you express in words how the invalidate my point? And do you actually know how RISC-V machine/supervisor/user/hypervisor modes work? I assure you, it's just a few instructions to switch between them, so my point still stands, unless I'm wrong about that, which I am not. So let's move on.

> qemu

A poor substitute for running on real hardware, from a psychological perspective. Just look at how people nerd out on HN about porting Doom to a smartwatch. People like to run things on hardware: fact. PCs are more ubiquitous than RISC-V boards which you have to order online: fact.

> Intel hate keeping tech is irrelevant [I don’t care]

I didn't get it, can you explain?

> Also, it runs Minix

Everyone knows this already, it makes the front page of HN at least once per year.

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