diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/libstore/globals.hh | 56 |
1 files changed, 32 insertions, 24 deletions
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh index d4b8fb1f9..723d18d74 100644 --- a/src/libstore/globals.hh +++ b/src/libstore/globals.hh @@ -193,18 +193,24 @@ public: Setting<std::string> thisSystem{ this, SYSTEM, "system", R"( - This option specifies the canonical Nix system name of the current - installation, such as `i686-linux` or `x86_64-darwin`. Nix can only - build derivations whose `system` attribute equals the value - specified here. In general, it never makes sense to modify this - value from its default, since you can use it to ‘lie’ about the - platform you are building on (e.g., perform a Mac OS build on a - Linux machine; the result would obviously be wrong). It only makes - sense if the Nix binaries can run on multiple platforms, e.g., - ‘universal binaries’ that run on `x86_64-linux` and `i686-linux`. - - It defaults to the canonical Nix system name detected by `configure` - at build time. + The system type of the current Nix installation. + Nix will only build a given [derivation](@docroot@/language/derivations.md) locally when its `system` attribute equals any of the values specified here or in [`extra-platforms`](#conf-extra-platforms). + + The default value is set when Nix itself is compiled for the system it will run on. + The following system types are widely used, as [Nix is actively supported on these platforms](@docroot@/contributing/hacking.md#platforms): + + - `x86_64-linux` + - `x86_64-darwin` + - `i686-linux` + - `aarch64-linux` + - `aarch64-darwin` + - `armv6l-linux` + - `armv7l-linux` + + In general, you do not have to modify this setting. + While you can force Nix to run a Darwin-specific `builder` executable on a Linux machine, the result would obviously be wrong. + + This value is available in the Nix language as [`builtins.currentSystem`](@docroot@/language/builtin-constants.md#builtins-currentSystem). )"}; Setting<time_t> maxSilentTime{ @@ -670,18 +676,20 @@ public: getDefaultExtraPlatforms(), "extra-platforms", R"( - Platforms other than the native one which this machine is capable of - building for. This can be useful for supporting additional - architectures on compatible machines: i686-linux can be built on - x86\_64-linux machines (and the default for this setting reflects - this); armv7 is backwards-compatible with armv6 and armv5tel; some - aarch64 machines can also natively run 32-bit ARM code; and - qemu-user may be used to support non-native platforms (though this - may be slow and buggy). Most values for this are not enabled by - default because build systems will often misdetect the target - platform and generate incompatible code, so you may wish to - cross-check the results of using this option against proper - natively-built versions of your derivations. + System types of executables that can be run on this machine. + + Nix will only build a given [derivation](@docroot@/language/derivations.md) locally when its `system` attribute equals any of the values specified here or in the [`system` option](#conf-system). + + Setting this can be useful to build derivations locally on compatible machines: + - `i686-linux` executables can be run on `x86_64-linux` machines (set by default) + - `x86_64-darwin` executables can be run on macOS `aarch64-darwin` with Rosetta 2 (set by default where applicable) + - `armv6` and `armv5tel` executables can be run on `armv7` + - some `aarch64` machines can also natively run 32-bit ARM code + - `qemu-user` may be used to support non-native platforms (though this + may be slow and buggy) + + Build systems will usually detect the target platform to be the current physical system and therefore produce machine code incompatible with what may be intended in the derivation. + You should design your derivation's `builder` accordingly and cross-check the results when using this option against natively-built versions of your derivation. )", {}, false}; Setting<StringSet> systemFeatures{ |