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nix-community / nixos-generators

Collection of image builders [maintainer=@Lassulus]
MIT License
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Cross compiling from aarch64-darwin? #187

Closed supermarin closed 1 year ago

supermarin commented 1 year ago

For some reason I lived under impression that I was cross compiling a qcow aarch64-linux vm from a M1 mac. Turns out I was initially building the VM with a linux laptop and scp-ed ./result over to the mac. Taking a quick look into flake.nix I see that x86_64-darwin is supported but aarch64-darwin is not. I tried adding aarch64-darwin there but didn't make much progress. Am I missing something obvious, and would it be feasible to add this support in?

Mic92 commented 1 year ago

I think you need to choose the aarch64-linux output and have a aarch64-linux remote builder (maybe running in a VM). I don't think you can build nixos closures on macOS otherwise. You can use the nixosGenerate function for that: https://github.com/Mic92/dotfiles/blob/master/nixos/images/default.nix#L40

supermarin commented 1 year ago

@Mic92 thanks, I'm using nixosGenerate but not sure how to pass in a remote builder option. Is there a way to use a remote builder with nix build CLI that I'm missing?

Mic92 commented 1 year ago

You need to pass the builder option to nix build not nixosGenerate:

This is an example for nix-ld

nix build --builders 'ssh-ng://nix@yasmin.dse.in.tum.de aarch64-linux /run/secrets/id_buildfarm 224 1 big-parallel,kvm,nixos-test - -' .#packages.aarch64-linux.nix-ld

/run/secrets/id_buildfarm is my private ssh key and ssh-ng://nix@yasmin.dse.in.tum.de my aarch64 builder.

supermarin commented 1 year ago

Wasn't aware of the --builders flag and have been looking for something like this! nix help build man page doesn't list the option. Where is this documented?

Mic92 commented 1 year ago

These types of option are documented here: https://nixos.org/manual/nix/stable/command-ref/conf-file.html

supermarin commented 1 year ago

@Mic92 that's ... the last place I'd be looking for it, and it's poorly documented at best.

Is there a reason this CLI flag is not referenced in man pages? I was initially looking in here but it's not clear to me how the man pages are generated/organized without spending significant amount of time.

Mic92 commented 1 year ago

Because it builder actually a nix setting you would have in your configuration and not a command line flag, from nix.conf manpage:

You can override settings on the command line using the --option flag, e.g. --option keep-outputs false. Every configuration setting also has a corresponding command line flag, e.g. --max-jobs 16; for Boolean set‐ tings, there are two flags to enable or disable the setting (e.g. --keep-failed and --no-keep-failed).

I am closing this, because this is no longer in scope of nixos-generators.