| 4 Dec 2025 |
 Alexandros Liarokapis | any idea what is the difference between torch-bin and torchWithCuda ? | 12:28:06 |
 Robbie Buxton | In reply to @aliarokapis:matrix.org
any idea what is the difference between torch-bin and torchWithCuda ? Iirc torch-bin is torch not built from source and torchWithCuda is torch built from source with cuda enabled forced regardless of global configuration? | 13:34:25 |
 Gaétan Lepage | Yes, this is it. | 13:46:25 |
| Alexandros Liarokapis | and it is apparently in the nixos cache by defualt? | 14:05:18 |
| Alexandros Liarokapis | * and it is apparently in the nixos cache by default? | 14:16:57 |
| Gaétan Lepage | I'm not sure torchWithCuda will be.
For `cudaSupport-enabled packages, consider using the Flox binary cache, or the NixOS-CUDA one. | 14:28:52 |
 connor (burnt/out) (UTC-8) | I’ll try to answer this later today. Depending on how comfortable you are with Nix, pull in the overlay for CUDA-legacy (https://github.com/nixos-cuda/cuda-legacy) to add a bunch of manifests and then customize the package set to your liking by using override on the CUDA package set and providing the manifest version you want. The docs are lacking an example for this.
As you discovered, NVCC may support capabilities but that doesn’t mean the big libraries most people use (cuDNN, libcublas, TensorRT, etc.) do. We have the unenviable job of either adopting the latest release for each version or fixing them in time and never updating. The decision is made more difficult by the fact NVIDIA seems to fix bugs by doing major/minor releases much more often than patch releases.
The trace-verbose thing is handy but undocumented and only exists because implementations of the Problems RFC keep getting bikeshedded to death.
We should probably have a section in the CUDA docs which list supported capabilities for each package set. Could be automatically generated given I added the available capabilities for each release to backendStdenv.
| 16:28:20 |
| connor (burnt/out) (UTC-8) | god i hate computers | 16:29:35 |
| connor (burnt/out) (UTC-8) | Reminder to self: post about changes I’ve been working on / need (fix adding attributes to backendStdenv, nvcc multiple outputs again, ccache) | 16:33:13 |
 SomeoneSerge (back on matrix) |
problems rfc
Tha release was cut off, IMO we should push a half-assed partial impl as per my closed PR in, bc 99% of the features we don't care about
| 19:52:52 |
| SomeoneSerge (back on matrix) |
stdenv attributes
...also nuke the other 90% attributes that don't actually belong and aren't even used
| 19:53:40 |
 corroding556 | Thank you so much! cuda-legacy was exactly what I needed.
Managed to get the configuration successfully built and deployed, going to try out an application which uses CUDA soon to verify everything is in working order.
Unenviable does seem like an appropriate word, digging into all this really made me appreciate how much work goes into making any of this possible.
Pointing folks like myself on older/unsupported hardware towards cuda-legacy (an example in the wiki/manual would be great) seems like a reasonable way to do things. | 23:52:06 |
| 5 Dec 2025 |
| connor (burnt/out) (UTC-8) | Changes I've been working on:
- https://github.com/NixOS/nixpkgs/pull/467975
- https://github.com/NixOS/nixpkgs/pull/467976 (both nvcc.profile and reintroducing multiple outputs for nvcc)
| 02:05:17 |
 Kevin Mittman (UTC-7) | So CUDA 13.1 released today
https://developer.download.nvidia.com/compute/cuda/redist/redistrib_13.1.0.json | 03:34:00 |
| Kevin Mittman (UTC-7) | Now includes a binary archive tarball for cuda_compat (not for Jetson Orin) "forward compatibility" | 03:36:07 |
| Gaétan Lepage | Hi connor (burnt/out) (UTC-8)
What are you thoughts on https://github.com/NixOS/nixpkgs/pull/465751?
Not ideal as it does not solve the import issue for reverse dependencies, but at least it would allow me to move on with the vllm update. | 21:42:43 |
| 6 Dec 2025 |
| connor (burnt/out) (UTC-8) | I think it’s fine | 15:38:45 |
| Gaétan Lepage | Thanks. Can you approve the PR please? I want to avoid "self-merging" it. | 22:57:54 |
| 7 Dec 2025 |
| Gaétan Lepage | Thanks connor (burnt/out) (UTC-8)!
Actually, I was wondering whether the stubs could fix the import at build time... | 11:11:53 |
| Gaétan Lepage | Indeed (I'm quite dumb for not having made the link sooner) this issue is caused by https://github.com/NixOS/nixpkgs/pull/459416/commits/9d38d180dba19909a6058a4e16ffa1803536c4d8.
Is there a way I could disable this for this package? | 11:50:49 |
| Gaétan Lepage | Opened https://github.com/NixOS/nixpkgs/pull/468659. I think it's way better than my previous solution. | 14:24:33 |
| connor (burnt/out) (UTC-8) | Left a comment | 17:11:27 |
| Gaétan Lepage | Thanks a lot. Working on a better solution. | 17:26:06 |
| 8 Dec 2025 |
 adrian-gierakowski | is it expected for cudaSupport=true to cause nix itself to be rebuilt? https://github.com/NixOS/nixpkgs/issues/468947 | 11:22:53 |
| adrian-gierakowski | looks like so tests related deps causing this | 11:23:29 |
| adrian-gierakowski | * looks like so tests related deps causing this:
> nix why-depends /nix/store/rf0rkc1p07vgrc25b6br3f35aipipp3g-nix-2.32.4 /nix/store/awc75hb0iz3gnb4qbg3z1g9lk8jqiibi-hwloc-2.12.2-lib
/nix/store/rf0rkc1p07vgrc25b6br3f35aipipp3g-nix-2.32.4
└───/nix/store/i7chz8mn48rgmm1y8a6yy6gk6bs2dv8m-nix-2.32.4
└───/nix/store/3pvks90shqql6bvb67cc88n21r7b3sx0-nix-util-2.32.4
└───/nix/store/iq2bbr1l3ka2yfjc93gswsp43xr9a6mr-libblake3-1.8.2
└───/nix/store/bk2q02fwz5mxa4xvblcl1p89ygllm04f-onetbb-2022.3.0
└───/nix/store/awc75hb0iz3gnb4qbg3z1g9lk8jqiibi-hwloc-2.12.2-lib
| 11:26:18 |
| adrian-gierakowski | Maybe I shouldn't set cudaSupport = true systemwide, but create a separate instance of pkgs for just those package which need cudaSupport? | 12:51:02 |
 Albert Larsan | It used to rebuild at least as far back as 25.05, and still rebuilds on 25.11.
Some NixOS options change defaults based on the cudaSupport/rocmSupport values. | 12:59:11 |
| adrian-gierakowski | Thanks @albertlarsan68:albertlarsan.fr! So would you still recommend setting cudaSupport at system level? | 14:29:37 |
| Albert Larsan | That is what I do for the machines that have an Nvidia GPU, for which I eat the cost of building nix (although I have a private binary cache to which I push the closures of the updated machines before uploading the flake update to the machines) | 14:36:59 |
