diff options
| -rw-r--r-- | doc/cross-compilation.xml | 20 | ||||
| -rw-r--r-- | pkgs/top-level/all-packages.nix | 6 | ||||
| -rw-r--r-- | pkgs/top-level/default.nix | 47 | ||||
| -rw-r--r-- | pkgs/top-level/impure.nix | 19 |
4 files changed, 53 insertions, 39 deletions
diff --git a/doc/cross-compilation.xml b/doc/cross-compilation.xml index 32cf198449b..8e981a4318e 100644 --- a/doc/cross-compilation.xml +++ b/doc/cross-compilation.xml @@ -25,7 +25,7 @@ <!--============================================================--> <section xml:id="sec-cross-packaging"> - <title>Packing in a cross-friendly manner</title> + <title>Packaging in a cross-friendly manner</title> <section> <title>Platform parameters</title> @@ -132,9 +132,23 @@ <section xml:id="sec-cross-usage"> <title>Cross-building packages</title> + <note><para> + More information needs to moved from the old wiki, especially <link xlink:href="https://nixos.org/wiki/CrossCompiling" />, for this section. + </para></note> + <para> + Many sources (manual, wiki, etc) probably mention passing <varname>system</varname>, <varname>platform</varname>, and, optionally, <varname>crossSystem</varname> to nixpkgs: + <literal>import <nixpkgs> { system = ..; platform = ..; crossSystem = ..; }</literal>. + <varname>system</varname> and <varname>platform</varname> together determine the system on which packages are built, and <varname>crossSystem</varname> specifies the platform on which packages are ultimately intended to run, if it is different. + This still works, but with more recent changes, one can alternatively pass <varname>localSystem</varname>, containing <varname>system</varname> and <varname>platform</varname>, for symmetry. + </para> <para> - To be written. - This is basically unchanged so see the old wiki for now. + One would think that <varname>localSystem</varname> and <varname>crossSystem</varname> overlap horribly with the three <varname>*Platforms</varname> (<varname>buildPlatform</varname>, <varname>hostPlatform,</varname> and <varname>targetPlatform</varname>; see <varname>stage.nix</varname> or the manual). + Actually, those identifiers are purposefully not used here to draw a subtle but important distinction: + While the granularity of having 3 platforms is necessary to properly *build* packages, it is overkill for specifying the user's *intent* when making a build plan or package set. + A simple "build vs deploy" dichotomy is adequate: the sliding window principle described in the previous section shows how to interpolate between the these two "end points" to get the 3 platform triple for each bootstrapping stage. + That means for any package a given package set, even those not bound on the top level but only reachable via dependencies or <varname>buildPackages</varname>, the three platforms will be defined as one of <varname>localSystem</varname> or <varname>crossSystem</varname>, with the former replacing the latter as one traverses build-time dependencies. + A last simple difference then is <varname>crossSystem</varname> should be null when one doesn't want to cross-compile, while the <varname>*Platform</varname>s are always non-null. + <varname>localSystem</varname> is always non-null. </para> </section> diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix index e066d1ababd..fc6b1e41d53 100644 --- a/pkgs/top-level/all-packages.nix +++ b/pkgs/top-level/all-packages.nix @@ -18,8 +18,10 @@ with pkgs; # Override system. This is useful to build i686 packages on x86_64-linux. forceSystem = system: kernel: nixpkgsFun { - inherit system; - platform = platform // { kernelArch = kernel; }; + localSystem = { + inherit system; + platform = platform // { kernelArch = kernel; }; + }; }; # Used by wine, firefox with debugging version of Flash, ... diff --git a/pkgs/top-level/default.nix b/pkgs/top-level/default.nix index 3c67d316f7c..3e3ecdeea6c 100644 --- a/pkgs/top-level/default.nix +++ b/pkgs/top-level/default.nix @@ -17,8 +17,14 @@ evaluation is taking place, and the configuration from environment variables or dot-files. */ -{ # The system (e.g., `i686-linux') for which to build the packages. - system +{ # The system packages will be built on. See the manual for the + # subtle division of labor between these two `*System`s and the three + # `*Platform`s. + localSystem + + # The system packages will ultimately be run on. Null if the two should be the + # same. +, crossSystem ? null , # Allow a configuration attribute set to be passed in as an argument. config ? {} @@ -27,12 +33,9 @@ overlays ? [] , # A function booting the final package set for a specific standard - # environment. See below for the arguments given to that function, - # the type of list it returns. + # environment. See below for the arguments given to that function, the type of + # list it returns. stdenvStages ? import ../stdenv - -, crossSystem ? null -, platform ? assert false; null } @ args: let # Rename the function arguments @@ -51,10 +54,10 @@ in let # Allow setting the platform in the config file. Otherwise, let's use a # reasonable default. - platform = - args.platform - or ( config.platform - or ((import ./platforms.nix).selectPlatformBySystem system) ); + localSystem = + { platform = (import ./platforms.nix).selectPlatformBySystem args.localSystem.system; } + // builtins.intersectAttrs { platform = null; } config + // args.localSystem; # A few packages make a new package set to draw their dependencies from. # (Currently to get a cross tool chain, or forced-i686 package.) Rather than @@ -71,7 +74,8 @@ in let # To put this in concrete terms, this function is basically just used today to # use package for a different platform for the current platform (namely cross # compiling toolchains and 32-bit packages on x86_64). In both those cases we - # want the provided non-native `system` argument to affect the stdenv chosen. + # want the provided non-native `localSystem` argument to affect the stdenv + # chosen. nixpkgsFun = newArgs: import ./. (args // newArgs); # Partially apply some arguments for building bootstraping stage pkgs @@ -83,24 +87,7 @@ in let boot = import ../stdenv/booter.nix { inherit lib allPackages; }; stages = stdenvStages { - # One would think that `localSystem` and `crossSystem` overlap horribly with - # the three `*Platforms` (`buildPlatform`, `hostPlatform,` and - # `targetPlatform`; see `stage.nix` or the manual). Actually, those - # identifiers I, @Ericson2314, purposefully not used here to draw a subtle - # but important distinction: - # - # While the granularity of having 3 platforms is necessary to properly - # *build* packages, it is overkill for specifying the user's *intent* when - # making a build plan or package set. A simple "build vs deploy" dichotomy - # is adequate: the "sliding window" principle described in the manual shows - # how to interpolate between the these two "end points" to get the 3 - # platform triple for each bootstrapping stage. - # - # Also, less philosophically but quite practically, `crossSystem` should be - # null when one doesn't want to cross-compile, while the `*Platform`s are - # always non-null. `localSystem` is always non-null. - localSystem = { inherit system platform; }; - inherit lib crossSystem config overlays; + inherit lib localSystem crossSystem config overlays; }; pkgs = boot stages; diff --git a/pkgs/top-level/impure.nix b/pkgs/top-level/impure.nix index 6999b7428ba..98094e93160 100644 --- a/pkgs/top-level/impure.nix +++ b/pkgs/top-level/impure.nix @@ -12,9 +12,11 @@ let in -{ # Fallback: Assume we are building packages for the current (host, in GNU - # Autotools parlance) system. - system ? builtins.currentSystem +{ # We combine legacy `system` and `platform` into `localSystem`, if + # `localSystem` was not passed. Strictly speaking, this is pure desugar, but + # it is most convient to do so before the impure `localSystem.system` default, + # so we do it now. + localSystem ? builtins.intersectAttrs { system = null; platform = null; } args , # Fallback: The contents of the configuration file found at $NIXPKGS_CONFIG or # $HOME/.config/nixpkgs/config.nix. @@ -49,4 +51,13 @@ in , ... } @ args: -import ./. (args // { inherit system config overlays; }) +# If `localSystem` was explicitly passed, legacy `system` and `platform` should +# not be passed. +assert args ? localSystem -> !(args ? system || args ? platform); + +import ./. (builtins.removeAttrs args [ "system" "platform" ] // { + inherit config overlays; + # Fallback: Assume we are building packages on the current (build, in GNU + # Autotools parlance) system. + localSystem = { system = builtins.currentSystem; } // localSystem; +}) |