| 7 Dec 2025 |
 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 |
| 9 Dec 2025 |
| connor (burnt/out) (UTC-8) | Gaétan Lepage: SomeoneSerge (back on matrix): could one of you approve/merge https://github.com/NixOS/nixpkgs/pull/467975? | 00:09:23 |
 SomeoneSerge (back on matrix) | Robbie Buxton: have you seen https://linus.schreibt.jetzt/posts/ubuntu-images.html? Also stumbled on https://github.com/numtide/nix-vm-test while trying to remember the url | 16:35:16 |
| SomeoneSerge (back on matrix) | Nix in this case is just a tool we already had for memoization and isolation, it just happens to come with a particularly shitty scheduler | 16:36:28 |
 Robbie Buxton | No I haven’t, I’ll take a look, cheers! | 16:37:26 |
| SomeoneSerge (back on matrix) | Any other memoization solution one could build must necessarily be a version of Nix (on top of the actual Nix), likely stripped down and using heuristics instead of trying to faithfully compute the hash "of that and only that which matters"... | 16:38:47 |
| SomeoneSerge (back on matrix) | Which with the current state of affairs is probably cheaper and more efficient 🤷 | 16:39:14 |
| SomeoneSerge (back on matrix) | But mathematically still the same thing | 16:39:27 |
 tomberek | Anyone using impure derivations to explicitly have non-caching behavior? | 16:42:29 |
| SomeoneSerge (back on matrix) | No, that's not really useful? | 17:07:37 |
