micropython: fix cross

--- a/ports/unix/Makefile

+++ b/ports/unix/Makefile

@@ -31,7 +31,7 @@

 QSTR_GLOBAL_DEPENDENCIES += $(VARIANT_DIR)/mpconfigvariant.h

 # OS name, for simple autoconfig

-UNAME_S := $(shell uname -s)

+UNAME_S := @UNAME_S@

 # include py core make definitions

 include $(TOP)/py/py.mk

@@ -151,7 +151,7 @@

 # If the variant enables it, enable modbluetooth.

 ifeq ($(MICROPY_PY_BLUETOOTH),1)

 ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)

-HAVE_LIBUSB := $(shell (which pkg-config > /dev/null && pkg-config --exists libusb-1.0) 2>/dev/null && echo '1')

+HAVE_LIBUSB := $(shell (which @PKG_CONFIG@ > /dev/null && @PKG_CONFIG@ --exists libusb-1.0) 2>/dev/null && echo '1')

 # Figure out which BTstack transport to use.

 ifeq ($(HAVE_LIBUSB),1)

@@ -180,8 +180,8 @@

  endif

 else

 # Use system version of libffi.

-LIBFFI_CFLAGS := $(shell pkg-config --cflags libffi)

-LIBFFI_LDFLAGS := $(shell pkg-config --libs libffi)

+LIBFFI_CFLAGS := $(shell @PKG_CONFIG@ --cflags libffi)

+LIBFFI_LDFLAGS := $(shell @PKG_CONFIG@ --libs libffi)

 endif

 ifeq ($(UNAME_S),Linux)

--- a/mpy-cross/mpy_cross/__init__.py

+++ b/mpy-cross/mpy_cross/__init__.py

@@ -61,6 +61,10 @@

 def _find_mpy_cross_binary(mpy_cross):

     if mpy_cross:

         return mpy_cross

+    # Check for MPY_CROSS environment variable first (for cross-compilation)

+    env_mpy_cross = os.environ.get("MPY_CROSS")

+    if env_mpy_cross:

+        return env_mpy_cross

     return os.path.abspath(os.path.join(os.path.dirname(__file__), "../build/mpy-cross"))

  python3,

  libffi,

  readline,

  buildPackages,

}:

stdenv.mkDerivation rec {

      extraPrefix = "lib/mbedtls/";

      hash = "sha256-Sllp/iWWEhykMJ3HALw5KzR4ta22120Jcl51JZCkZE0=";

    })

    ./fix-cross-compilation.patch

    ./fix-mpy-cross-path.patch

  ];

  postPatch = ''

    # Fix cross-compilation by replacing uname and pkg-config

    substituteInPlace ports/unix/Makefile \

      --subst-var-by UNAME_S "${

        {

          "x86_64-linux" = "Linux";

          "i686-linux" = "Linux";

          "aarch64-linux" = "Linux";

          "armv7l-linux" = "Linux";

          "armv6l-linux" = "Linux";

          "riscv64-linux" = "Linux";

          "powerpc64le-linux" = "Linux";

          "x86_64-darwin" = "Darwin";

          "aarch64-darwin" = "Darwin";

        }

        .${stdenv.hostPlatform.system} or stdenv.hostPlatform.parsed.kernel.name

      }" \

      --subst-var-by PKG_CONFIG "${stdenv.cc.targetPrefix}pkg-config"

  '';

  depsBuildBuild = [

    buildPackages.stdenv.cc

    buildPackages.python3

  ];

  nativeBuildInputs = [

  makeFlags = [

    "-C"

    "ports/unix"

    "CROSS_COMPILE=${stdenv.cc.targetPrefix}"

  ]

  ++ lib.optionals (stdenv.hostPlatform.isAarch64 && stdenv.hostPlatform.isLinux) [

    # Workaround for false positive gcc warning in mbedtls on aarch64

    "CFLAGS_EXTRA=-Wno-array-bounds"

  ]; # also builds mpy-cross

  # Build mpy-cross for the build platform first when cross-compiling

  preBuild = ''

    # Build mpy-cross for the build platform

    make -C mpy-cross \

      CC="${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc" \

      CROSS_COMPILE=""

  ''

  + lib.optionalString (stdenv.buildPlatform != stdenv.hostPlatform) ''

    # Set MPY_CROSS environment variable for cross-compilation

    export MPY_CROSS="$PWD/mpy-cross/build/mpy-cross"

  '';

  enableParallelBuilding = true;

  doCheck = true;

    runHook preInstall

    mkdir -p $out/bin

    install -Dm755 ports/unix/build-standard/micropython -t $out/bin

    install -Dm755 mpy-cross/build/mpy-cross -t $out/bin

    runHook postInstall

  '';