Cross Compiling: Difference between revisions

Line 26:

and then use it to obtain a shell:

The resulting shell ~~will have~~ <code>$CC</code> ~~etc~~. ~~set to the right compiler~~.

The resulting shell contains a cross toolchain and zlib in this example. Note that contrary to native shells, the compiler and some other tools are prefixed: there is no <code>gcc</code> but a <code>aarch64-unknown-linux-gnu-gcc</code>. Some convenience environment variables expand to the prefixed version of tools: <code>$CC</code>, <code>$LD</code>...

Examples of how to specify your target system can be found in [https://github.com/NixOS/nixpkgs/blob/master/lib/systems/examples.nix lib/systems/examples.nix].

Examples of how to specify your target system can be found in [https://github.com/NixOS/nixpkgs/blob/master/lib/systems/examples.nix lib/systems/examples.nix]. If the exact system you are targeting is available in this file then you can use the existing definition as in the following example:

let pkgs = import <nixpkgs> {

crossSystem = (import <nixpkgs/lib>).systems.examples.armv7l-hf-multiplatform;

};

in

...

</syntaxhighlight>

The ~~example~~ above ~~does~~ not work as is with build dependencies (<code>nativeBuildInputs</code>). A solution is to use <code>callPackage</code> to enable splicing:

The examples above do not work as is with build dependencies (<code>nativeBuildInputs</code>). A solution is to use <code>callPackage</code> to enable splicing:

let pkgs = import <nixpkgs> {

@@ Line 26: / Line 26: @@
 and then use it to obtain a shell:
 {{commands|nix-shell crossShell.nix}}
-The resulting shell will have <code>$CC</code> etc. set to the right compiler.
+The resulting shell contains a cross toolchain and zlib in this example. Note that contrary to native shells, the compiler and some other tools are prefixed: there is no <code>gcc</code> but a <code>aarch64-unknown-linux-gnu-gcc</code>. Some convenience environment variables expand to the prefixed version of tools: <code>$CC</code>, <code>$LD</code>...
-Examples of how to specify your target system can be found in [https://github.com/NixOS/nixpkgs/blob/master/lib/systems/examples.nix lib/systems/examples.nix].
+Examples of how to specify your target system can be found in [https://github.com/NixOS/nixpkgs/blob/master/lib/systems/examples.nix lib/systems/examples.nix]. If the exact system you are targeting is available in this file then you can use the existing definition as in the following example:
+<syntaxhighlight lang="nix">
+let pkgs = import <nixpkgs> {
+    crossSystem = (import <nixpkgs/lib>).systems.examples.armv7l-hf-multiplatform;
+};
+in
+...
+</syntaxhighlight>
-The example above does not work as is with build dependencies (<code>nativeBuildInputs</code>). A solution is to use <code>callPackage</code> to enable splicing:
+The examples above do not work as is with build dependencies (<code>nativeBuildInputs</code>). A solution is to use <code>callPackage</code> to enable splicing:
 <syntaxhighlight lang="nix">
 let pkgs = import <nixpkgs> {