Rust Lands Support For The Motorola 68000 Processors

[ssokolow]

Can you actually run rustc on m68k machines to compile code there?

As far as I know, no m68k machine has enough RAM to run rustc, so it'd just be for cross-compiling.

[mdedetrich]

Ah this is cool.

I put together a Mega Drive (GCC based) toolchain a while back (here). Would be really interesting to do similar for Rust.

It is also great to see Rust targeting a wider range of platforms. This does increase my confidence in it.

Rust has an entire steering group around it https://github.com/rust-embedded/wg, they are taking it very seriously

[Chewi]

Can you actually run rustc on m68k machines to compile code there?

As I discovered after actually looking at the PR and the README within, you can't build the simplest of code at all yet. It's missing std and core. I've seen example code without std, but no core seems practically impossible. They'll surely get wired up soon though, or what would be the point?

I tried to build LLVM 13.0.0-rc3 for m68k on Gentoo, and it failed due to some integer overflow. The README does say native building is "untested" at the moment, so maybe this is expected. Debian (via debports) does appear to have LLVM 12 packaged for m68k. Maybe they've patched it (not sure where to look), but that release was before the m68k target was added anyway.

[Chewi]

As far as I know, no m68k machine has enough RAM to run rustc, so it'd just be for cross-compiling.

True for real hardware, my Amiga only has 128MB. I've managed to get ARAnyM running Linux with around 768MB, but that's probably still not enough. The new QEMU virtual m68k machine can have up to 3GB though, which probably is enough. I've been using that with great success to build Gentoo packages lately.

[OneTimeShot]

I think the 68020 and above have a full 32 bit address bus, so 4Gb should be doable.

IIrC AmigaOS gets confused after 1.5Gb, so probably needs patching….

[cb88]

Can you actually run rustc on m68k machines to compile code there?

No its not self hosting... this is just cross compiler output support (all rustc compilers are cross compilers)

[Vistaus]

IIrC AmigaOS gets confused after 1.5Gb, so probably needs patching….

I think I've read reports that that doesn't happen anymore with the recent AmigaOS 3.1.x upgrades for the 68K20 (yes, even old AmigaOS 3.1.x still receives upgrades, along with the more current 4.x (4.x gets weekly updates through the update manager)!).

[Developer12]

Nah, it's not just about the CPU. You need hardware drivers too, and the Amiga's hardware is very special, especially the graphics hardware. Even on Linux, you can't do much graphical stuff. You get a basic framebuffer, but it's only good for text and the Tux logo. You can run X but it has to do some CPU-killing pixel format conversions.

So write new drivers? The hardware's well documented and Redox's architecture is quite flexible.

[Chewi]

So write new drivers? The hardware's well documented and Redox's architecture is quite flexible.

Just like that, eh? I've got more than enough to do, thanks.

[Developer12]

Just like that, eh? I've got more than enough to do, thanks.

Yes, just like that. It's a straightforward job for anyone doing a port.

It's also worth noting that Redox picked up Meltdown protection in only 3 days of work. It's design really does make extensions easy and straightforward.