micropython: fix cross

pkgs/by-name/mi/micropython/fix-cross-compilation.patch

@@ -0,0 +1,31 @@
+--- 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)

pkgs/by-name/mi/micropython/fix-mpy-cross-path.patch

@@ -0,0 +1,13 @@
+--- 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"))
+ 
+ 

pkgs/by-name/mi/micropython/package.nix

@@ -7,6 +7,7 @@
   python3,
   libffi,
   readline,
+  buildPackages,
 }:
 
 stdenv.mkDerivation rec {
@@ -43,6 +44,33 @@ 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 = [
@@ -58,8 +86,25 @@ stdenv.mkDerivation rec {
   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;
@@ -87,7 +132,6 @@ stdenv.mkDerivation rec {
     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
   '';