My first attempt at getting cross compilers in nixpkgs.

My idea is to provide special stdenv expressions that will contain in the path
additional cross compilers. As most expressions for programs accept a stdenv parameter, 
we could substitute this parameter with the special stdenv, which will have a
generic builder that attempts the usual "--target=..." and can additionally
have an env variable like "cross" with the target architecture set.
So, finally we could have additional expressions like this:

bashRealArm = makeOverridable (import ../shells/bash) {
    inherit fetchurl bison;
    stdenv = stdenvCross "armv5tel-unknown-linux-gnueabi";
};

Meanwhile it does not work - I still cannot get the cross-gcc to build.

I think it does not fill the previous expressions with a lot of noise, so I
think it may be a good path to follow.

I only touched some files of the current stdenv: gcc-4.3, kernel headers
2.6.28, glibc 2.9, ...

I tried to use the gcc-cross-wrapper, that may be very outdated. Maybe I will
update it, or update the gcc-wrapper expression to make it fit the cross tools,
but meanwhile I even cannot build gcc, so I have not tested the wrapper.

This new idea on cross compiling is not similar to that of the
nixpkgs/branches/cross-compilation, which mostly added bare new expressions for
anything to be cross compiled, if I understood it correctly.

I cared not to break anything of the usual stdenv in all this work.


svn path=/nixpkgs/branches/stdenv-updates/; revision=18343

1 files changed, 3 insertions, 1 deletions

diff --git a/pkgs/os-specific/linux/kernel-headers/2.6.28.nix b/pkgs/os-specific/linux/kernel-headers/2.6.28.nix
index 37891e6325b8..4591fee1497c 100644
--- a/pkgs/os-specific/linux/kernel-headers/2.6.28.nix
+++ b/pkgs/os-specific/linux/kernel-headers/2.6.28.nix
@@ -1,4 +1,4 @@
-{stdenv, fetchurl, perl}:
+{stdenv, fetchurl, perl, cross ? null}:
 
 assert stdenv.isLinux;
 
@@ -12,7 +12,9 @@ stdenv.mkDerivation {
     sha256 = "0hifjh75sinifr5138v22zwbpqln6lhn65k8b57a1dyzlqca7cl9";
   };
 
+
   platform = 
+    if cross == "armv5tel-unknown-linux-gnueabi" then "arm" else
     if stdenv.system == "i686-linux" then "i386" else
     if stdenv.system == "x86_64-linux" then "x86_64" else
     if stdenv.system == "powerpc-linux" then "powerpc" else