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Comment by leni536 | Hacker News Reader

Is cross compilation out of the question?

I'd guess that the issue is running the `%install` and `%check` stages of the .spec file. The Python library rpy (to pull a random example from Marcin's PRs) runs rpy's pytest test suite and had to be modified to avoid running vector tests on RISC-V.

Obviously a solvable problem to split build and test but perhaps the time savings aren't worth the complexity.

https://src.fedoraproject.org/rpms/rpy/pull-request/4#reques...

Maybe the tests could be run with user-mode qemu instead of the whole thing running under qemu or on RISC-V hardware. Could possibly be more or less seamless with binfmt_misc being set up in the builders.

Near as I know, Fedora prefers native compilation for the builds.

Your question made me look up Arm's history in Fedora and came up on this 2012 LWN thread[1]. There's some discussion against cross-compilation already back then.

[1] https://lwn.net/Articles/487622/

It's usually an enormous pain to set up. QEMU is probably the best option.

Depends on the language, it's pretty trivial with Go.

Unless you use CGO. I've heard people using Zig (which has great cross compilation for the Zig language as well) to cross compile C with CGO though.

Yes, but they're compiling binutils.

Maybe there are issues I'm not aware of but using dockcross has made cross-compilation quite easy in my experience.

https://github.com/dockcross/dockcross

How does it handle .so version differences and glibc version differences between the container and the target system?

T2 manages to do it

https://t2linux.com/

Yocto, which we use at work, manages it just fine to build a whole embedded Linux distro. So I don't see why Fedora couldn't make it work if they wanted. You could even scp over the test suites to run that on native systems if you wanted.

Yocto manages it thanks to the tireless effort of a community of people maintaining patches and unholy hacks for a ton of software to make it cross compilable. And they have nowhere near the amount of recipes that Fedora has.

This is true, but the hacks are mostly in the C and C++ recipes as I understand it. Something like Rust or especially Go or Zig is far easier to cross compile.

I personally found cross compiling Rust easy, as long as you don't have C dependencies. If you have C dependencies it becomes way harder.

This suggests that spending time to upstream cross compilation fixes would be worth it for everyone, and probably even in the C world, 20% of the packages need 80% of the effort.

I wonder if Fedora packages any C and C++ software?

I wonder how much of Fedora is written in Rust?

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