| 21 Jan 2026 |
 Katalin 🔪 | add -i | 13:12:18 |
 Ihar Hrachyshka | I did use nixos-generators on Darwin to create virtualbox images. Why wouldn't it work? | 13:12:54 |
 K900 | Because you'd have to build some NixOS bits presumably? | 13:13:32 |
 Steve | That's exactly what I'm trying to do. Just for UTM. | 13:13:42 |
| Ihar Hrachyshka | Oh sure but you always have a Linux builder. | 13:14:00 |
 eveeifyeve | Looking at QEMU source code, it unfortunately doesn't. | 13:14:01 |
| K900 | I am still confused why you think this even matters | 13:14:15 |
| K900 | I don't know what exactly it does | 13:14:21 |
| K900 | But it does not introduce major CPU overhead | 13:14:29 |
| K900 | So I'm not sure what your problem is | 13:14:33 |
| Steve | -i brings "unrecognized flag". I'm using determinate Nix. Is that maybe the problem? | 13:14:39 |
| Katalin 🔪 | (but I do wonder why nix build also doesn't reset $HOME. I think usually it should be set to /homeless-shelter. probably doesn't do that when the sandbox is disabled?) | 13:14:40 |
| Katalin 🔪 | sudo -i | 13:14:47 |
| Steve | That's the output:
sudo determinate-nixd upgrade
You are already running the latest version of Determinate Nix (3.15.1).
echo $HOME
/Users/bob
nix build -L .#nixosConfigurations.installer-aarch64.config.formats.qcow-efi
evaluating derivation 'git+file:///Users/bob/coding#nixosConfigurations.installer-aarch64.config.formats.qcow-efi'
nixos-disk-image> warning: $HOME ('/build') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/empty')
nixos-disk-image> chmod: changing permissions of '/build': Operation not permitted
error: Cannot build '/nix/store/ylpcrwmdbr3f4q1sqjvdi8a2nbz671r2-nixos-disk-image.drv'.
Reason: builder failed with exit code 1.
Output paths:
/nix/store/6sbfv1lzjmr6aldy423x0gjplvwqhajk-nixos-disk-image
Last 2 log lines:
> warning: $HOME ('/build') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/empty')
> chmod: changing permissions of '/build': Operation not permitted
...
error: Build failed due to failed dependency
sudo nix build -L .#nixosConfigurations.installer-aarch64.config.formats.qcow-efi
warning: $HOME ('/Users/bob') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/root')
warning: $HOME ('/Users/bob') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/root')
nixos-disk-image> warning: $HOME ('/build') is not owned by you, falling back to the one defined in the 'passwd' file ('/var/empty')
nixos-disk-image> chmod: changing permissions of '/build': Operation not permitted
...
error: Build failed due to failed dependency
| 13:15:25 |
| Katalin 🔪 | well okay that's not the problem then | 13:15:49 |
| Katalin 🔪 | these are just warnings and it picks the correct one (-ish) anyway | 13:16:02 |
| eveeifyeve | QEMU can offer slower speeds when on a arm host than using the native framework that is optimized for apple hardware. | 13:16:12 |
| Katalin 🔪 | > chmod: changing permissions of '/build': Operation not permitted
this is the problem | 13:16:21 |
| K900 | Have you actually measured this | 13:16:22 |
| K900 | Because like | 13:16:25 |
| K900 | No | 13:16:26 |
| Katalin 🔪 | but I have no quick answer for what's going on there | 13:16:51 |
| Ihar Hrachyshka | In reply to @eveeifyeve:matrix.org
QEMU can offer slower speeds when on a arm host than using the native framework that is optimized for apple hardware. Actually curious if there are public benchmarks | 13:17:06 |
 Randy Eckenrode | QEMU doesn’t need to use the Vietualization framework to be hardware accelerated. There are other, lower level, ways of accomplishing that. | 13:17:19 |
| Steve | There is no /build directory. I've never configured such a thing. I seems like hardcoded somewhere ... | 13:17:36 |
| Randy Eckenrode | Mesa is working on support for passthrough Vulkan to a Darwin host. | 13:17:39 |
| Randy Eckenrode | It will support MoltenVK, but you’ll really only want to use KosmicKrisp. | 13:18:17 |
| eveeifyeve | There is public benchmarks of it here: https://github.com/lima-vm/lima/issues/1269 | 13:18:18 |
| Katalin 🔪 | inside the sandboxed nix build on linux, the cwd is /build afaik | 13:18:24 |
| Katalin 🔪 | I think you cannot do that on macOS due to no mount namespaces | 13:18:35 |
