qemu-user setup

config.nix

{
  packageOverrides = pkgs: rec {
    qemu-user-arm = pkgs.callPackage ./qemu-user.nix { user_arch = "arm"; };
    nix = pkgs.stdenv.lib.overrideDerivation pkgs.nix (oldAttrs: {
      patches = ./hax.patch;
    });
  };
}

hax.patch

diff -r -u nix-1.10-old/src/libstore/build.cc nix-1.10/src/libstore/build.cc
--- nix-1.10-old/src/libstore/build.cc  2015-09-03 13:52:06.000000000 -0300
+++ nix-1.10/src/libstore/build.cc      2015-10-14 02:51:19.910899012 -0300
@@ -1247,11 +1247,7 @@

 static bool canBuildLocally(const string & platform)
 {
-    return platform == settings.thisSystem
-#if __linux__
-        || (platform == "i686-linux" && settings.thisSystem == "x86_64-linux")
-#endif
-        ;
+    return true;
 }

qemu-user.nix

{ stdenv, fetchurl, python, pkgconfig, zlib, glib, user_arch, flex, bison }:

stdenv.mkDerivation rec {
  name = "qemu-user-${user_arch}-${version}";
  version = "2.4.0";
  buildInputs = [ python pkgconfig zlib glib flex bison ];
  src = fetchurl {
    url = "http://wiki.qemu.org/download/qemu-${version}.tar.bz2";
    sha256 = "0836gqv5zcl0xswwjcns3mlkn18lyz2fiq8rl1ihcm6cpf8vkc3j";
  };
  configureFlags = [
    "--enable-linux-user" "--target-list=${user_arch}-linux-user"
    "--disable-bsd-user" "--disable-system" "--disable-vnc" "--without-pixman"
    "--disable-vnc-tls" "--disable-curses" "--disable-sdl" "--disable-vde"
    "--disable-bluez" "--disable-kvm"
    #"--static"
    "--disable-tools"
  ];
}
# mount -v -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc/
# echo   ':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\x00\xff\xfe\xff\xff\xff:/nix/store/6lmqyaj2cijpw9qylyw6kll8vxzrngpq-qemu-user-arm-2.4.0/bin/qemu-arm:' > /proc/sys/fs/binfmt_misc/register