Cross Compiling: Difference between revisions
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lib = import <nixpkgs/lib>; | lib = import <nixpkgs/lib>; | ||
pkgs = import <nixpkgs> { | pkgs = import <nixpkgs> { | ||
#localSystem = ...; | |||
crossSystem = lib.systems.examples.aarch64-multiplatform; | crossSystem = lib.systems.examples.aarch64-multiplatform; | ||
}; | }; | ||
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{ | { | ||
pkgs ? import <nixpkgs> { | pkgs ? import <nixpkgs> { | ||
#localSystem = ...; | |||
crossSystem = "aarch64-linux"; | crossSystem = "aarch64-linux"; | ||
}, | }, | ||
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}: | }: | ||
mkShell { | mkShell { | ||
# Derivations that must run on | # Derivations that must run on the buildPlatform. | ||
nativeBuildInputs = [ | nativeBuildInputs = [ | ||
pkg-config | pkg-config | ||
]; | ]; | ||
# Derivations that must link with | # Derivations that must link with the targetPlatform. | ||
buildInputs = [ | buildInputs = [ | ||
libGL | libGL | ||
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By using [[QEMU]], we can natively execute a cross-compiled binary through an emulation layer. This will result in degraded performance but is very suitable for testing the functionality of a binary. | By using [[QEMU]], we can natively execute a cross-compiled binary through an emulation layer. This will result in degraded performance but is very suitable for testing the functionality of a binary. | ||
If you are on NixOS, this functionality can be provided automatically on any cross-compiled binary by setting [https://nixos.org/manual/nixos/unstable/options#opt-boot.binfmt.emulatedSystems boot.binfmt.emulatedSystems] in your configuration. After rebuilding, attempting to run a cross-compiled binary will automatically invoke <code>qemu</code> indirectly.<syntaxhighlight lang="bash"> | If you are on NixOS, this functionality can be provided automatically on any cross-compiled binary by setting [https://nixos.org/manual/nixos/unstable/options#opt-boot.binfmt.emulatedSystems boot.binfmt.emulatedSystems] in your configuration. After rebuilding, attempting to run a cross-compiled binary will automatically invoke <code>qemu</code> indirectly through the [https://www.kernel.org/doc/html/latest/admin-guide/binfmt-misc.html binfmt_misc kernel feature].<syntaxhighlight lang="bash"> | ||
$ ./result | $ ./result | ||
Hello World! | Hello World! | ||
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=== Leveraging the binary cache === | === Leveraging the binary cache === | ||
You will likely have noticed that resolving derivations through either pkgsCross or a configured Nixpkgs instance results in your system needing to build the binary. This is because cross-compiled binaries are not cached on the official [[Binary Cache|binary cache]]. | You will likely have noticed that resolving derivations through either pkgsCross or a configured Nixpkgs instance results in your system needing to build the binary. This is because cross-compiled binaries are not cached on the official [[Binary Cache|binary cache]]. Fortunately, there are a small set of systems that are actively built and cached officially. At the time of writing, this only includes <code>aarch64-linux</code>, <code>aarch64-darwin</code>, <code>i686-linux</code>, <code>x86_64-linux</code>, and <code>x86_64-darwin</code>. If your platform targets include these, you may be able to leverage a slight hack to avoid large-scale builds.<blockquote>Please note that this is not recommended, as it hacks around some internal details of Nixpkgs which are subject to change at any time.</blockquote>An example of this using <code>pkgs.SDL2</code>:<syntaxhighlight lang="nix"> | ||
let | let | ||
# this will use aarch64 binaries from binary cache, so no need to build those | # this will use aarch64 binaries from binary cache, so no need to build those | ||
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}) | }) | ||
]; | ]; | ||
#localSystem = ...; | |||
crossSystem = "aarch64-linux"; | crossSystem = "aarch64-linux"; | ||
}; | }; | ||
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* [https://logs.nix.samueldr.com/nixos/2018-08-03#1533327247-1533327971; 2018-08-03 discussion on #nixos] ([https://matrix.to/#/!AinLFXQRxTuqNpXyXk:matrix.org/$15333274371713496LOAor:matrix.org Mirror of chat on Matrix.org]) | * [https://logs.nix.samueldr.com/nixos/2018-08-03#1533327247-1533327971; 2018-08-03 discussion on #nixos] ([https://matrix.to/#/!AinLFXQRxTuqNpXyXk:matrix.org/$15333274371713496LOAor:matrix.org Mirror of chat on Matrix.org]) | ||
[[Category:nix]] | [[Category:nix]] | ||
[[Category:Development]] | [[Category:Development]] | ||