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I’m looking for advice on what board to get for starting an OS project for RISC-V? I’m a bit clueless with what to look for. I would most probably want a RV64GC ISA with more than one core. However, I don’t really care about performance.

The open questions that I have is BIOS. I’m guessing it should have something RISC-V SBI compatible. Would need to have some simple way of outputting text to a screen, so something similar to VGA text mode, so I can get output easily. Serial console is another option.

Finally, if there’s an emulator that could be used for faster development cycle at least for non-driver stuff, then that would help. Bonus points if I can upload the OS image over USB.

Does anything exist that anyone would recommend?

I think QEMU can support most stuff for emulation.

Some of my previous colleagues recommended https://www.sifive.com/boards/hifive-unmatched to me. At the time though, it was not available to buy. Stock might be limited. It's supposed to be friendly to developing stuff on it though and has quite a nice specification. Nice modern interfaces to hardware like M2 so you can play with that kind of stuff =]

BIOS is a PC platform thing by the way. Usually there's not really such a thing on RISC or embedded platforms afaik. Per board it might differ though. I've seen things where you just need to look how things are connected via what pins and then write to the right addreses to get to the framebuffer. Also others yet which need you to implement a little initialization code in a flash to setup stuff kind of like a bios does.

With embedded stuff it's usually more straight-forward than needing a BIOS as the platforms are usually more 'static', i.e. its not expected people will add/remove pci-devices and memory banks etc. like with a PC. Hence there's often not a need for such an interface to initialize or access the hardware.

eof wrote: ↑Sun Aug 18, 2024 5:15 amThe open questions that I have is BIOS. I’m guessing it should have something RISC-V SBI compatible.

I'd choose a board with U-Boot too. I'm pretty sure that'll make it easier to run your OS on different RISC-V boards in the future.

eof wrote: ↑Sun Aug 18, 2024 5:15 amWould need to have some simple way of outputting text to a screen, so something similar to VGA text mode, so I can get output easily.

You probably aren't going to find anything that resembles VGA text mode. Would a bitmap framebuffer work instead?

eof wrote: ↑Sun Aug 18, 2024 5:15 amFinally, if there’s an emulator that could be used for faster development cycle at least for non-driver stuff, then that would help.

QEMU. It emulates several different real RISC-V boards, plus a virtual board that's easier to set up than any real board.

sh42 wrote: ↑Thu Aug 29, 2024 6:54 amSome of my previous colleagues recommended https://www.sifive.com/boards/hifive-unmatched to me. At the time though, it was not available to buy.

There's a new revision, the original has been discontinued. That's a really nice board, I'm not even trying to do any RISC-V development and now I want one...