| 23 Nov 2025 |
 szlend | I assumed it must have been just for the shell, but I get the same thing with --no-shell | 12:52:29 |
| szlend | * Failing to evaluate it as a result (not available on the requested hostPlatform):
while evaluating attribute 'nativeBuildInputs' of derivation 'review-shell'
| 12:55:10 |
| 24 Nov 2025 |
|  Robert joined the room. | 13:22:42 |
| Robert changed their display name from bpub to Robert. | 13:31:59 |
| Robert set a profile picture. | 13:34:20 |
 siraben | this should work, can you provide the whole command" | 17:44:00 |
| siraben | * this should work, can you provide the whole command? | 17:44:06 |
| szlend | try nixpkgs-review -- pr --print-result 464677 --package pkgsCross.aarch64-multiplatform.libcap | 19:51:52 |
| szlend | it's a completely unrelated PR with no changes to libcap | 19:52:14 |
| szlend | but I can evaluate it fine without nixpkgs-review | 19:52:41 |
| siraben | 
Download Screenshot 2025-11-24 at 11.53.43.png | 19:54:07 |
| szlend | yeah I'm building from darwin | 19:54:30 |
| szlend | where it's not available. But it can be cross-compiled to linux | 19:54:50 |
| szlend | I mean it's broken in master until some changes from staging hit. But I should at least be able to evaluate it | 19:55:44 |
| szlend | 
Download image.png | 19:56:23 |
 Alyssa Ross | IIRC it's not still broken in master | 20:10:29 |
| Alyssa Ross | unless it broke again in the last couple of days | 20:10:39 |
 bake.monorail | Alyssa Ross when you have a minute can you take another look at the uclibc PR? | 20:15:34 |
| szlend | Alyssa Ross: there's one more libcap issue that I fixed here: https://github.com/NixOS/nixpkgs/pull/461685 | 20:31:16 |
| szlend | cross was fixed but not from darwin | 20:31:22 |
| Alyssa Ross | ah, I see | 20:32:04 |
| Alyssa Ross | I might not have a minute this week I'm afraid | 20:32:12 |
| szlend | got it to build manually but I can't confirm with nixpkgs-review :D | 20:32:13 |
|  André Lima set a profile picture. | 21:10:24 |
| 25 Nov 2025 |
|  eb joined the room. | 18:21:36 |
| eb | Hey all, I'm just starting to get into cross compiling (x68 -> aarch64 for rpi 4b), and have some questions about how to best approach this. I'll start with my understanding and situation to make sure I didn't make a mistake:
- I'm using flakes, which don't exactly have first class support for cross compilation.
- I'm manually creating my pi's
nixosConfigurations key and making my own nixpkgs.pkgs for it.
- It seems like for this
pkgs argument, I have two options: The first, is create it with localSystem == crossSystem == "aarch64-linux". If I do this, I'd need to rely on binmft style emulation to build from my x86 machine. The second, is create it with localSystem = x86-linux; crossSystem = "aarch64-linux". If I do this, I'm doing real cross compilation.
- With the former I can use
cache.nixos.org to grab the aarch64 components, but I'd need to emulate-build everything else.
- With the latter I can't use the cache at all, so I need to build everything.
Ideally I could use the cache and cross compile only if needed, but it looks like I can't do that without manually choosing specific packages to be cross compiled with pkgsCross attributes in the first method, right? And if I did want this, then my buildSystem would need to support emulation, right?
My buildSystem is currently Ubuntu, so I can't just flip the nixos switch for binfmt emulation. I could probably apply the binfmt config manually if I want to go the emulation route, right?
I suppose I might just be frustrated that I can't default crossSystem and opportunistically grab the non-cross packages from the aarch64 cache, though I know the technical reason why (store paths are functions of all inputs, and crossSystem is an input). I'm guessing this is currently an unsolved issue?
Thanks!
| 18:32:34 |
 Artturin | NixOS system cross is the exact same with flakes as it is without | 18:33:32 |
| eb | I get that; flakes are not my main issue on this. I'm just providing context there. | 18:35:43 |
| Artturin |
With the latter I can't use the cache at all, so I need to build everything.
There's some packages cached https://github.com/NixOS/nixpkgs/blob/75c025c6135ca219cded2592343bef3daa4b39b9/pkgs/top-level/release-cross.nix#L239
https://github.com/NixOS/nixpkgs/blob/75c025c6135ca219cded2592343bef3daa4b39b9/pkgs/top-level/release-cross.nix#L78-L105
| 18:37:22 |
| Artturin |
My buildSystem is currently Ubuntu, so I can't just flip the nixos switch for binfmt emulation. I could probably apply the binfmt config manually if I want to go the emulation route, right?
Yup binfmt is possible to setup on all distros
| 18:38:09 |
