Update to macOS SDK 26 and Metal 4 (#290)

- Switch to macOS 26 as the minimum requirement and support Metal 4.
- The hf-nix bump also requires some CUDA fixes, primarily nvcc now
wraps gcc correctly in nixpkgs, so we have to pass gcc with our glibc
backwards compatibility.

---------

Co-authored-by: Mohamed Mekkouri <93391238+MekkCyber@users.noreply.github.com>

Author: danieldk

.github/workflows/build_kernel_macos.yaml

@@ -10,8 +10,12 @@ on:
 jobs:
   build:
     name: Build kernel
-    runs-on: macos-latest
+    runs-on: macos-26
     steps:
+      - name: "Select Xcode"
+        run: sudo xcrun xcode-select -s /Applications/Xcode_26.0.app
+      - name: "Install Metal Toolchain"
+        run: xcodebuild -downloadComponent metalToolchain
       - uses: actions/checkout@v4
       - uses: cachix/install-nix-action@v31
       - uses: cachix/cachix-action@v15

build2cmake/src/templates/metal/compile-metal.cmake

@@ -1,11 +1,25 @@
 # Metal shader compilation function
 function(compile_metal_shaders TARGET_NAME METAL_SOURCES EXTRA_INCLUDE_DIRS)
-    # Find the Metal compiler
-    find_program(METAL_COMPILER xcrun REQUIRED)
-    
+    if(NOT DEFINED METAL_TOOLCHAIN)
+      execute_process(
+        COMMAND "xcodebuild" "-showComponent" "MetalToolchain"
+        OUTPUT_VARIABLE FIND_METAL_OUT
+        RESULT_VARIABLE FIND_METAL_ERROR_CODE
+        ERROR_VARIABLE FIND_METAL_STDERR
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+      if(NOT FIND_METAL_ERROR_CODE EQUAL 0)
+        message(FATAL_ERROR "${ERR_MSG}: ${FIND_METAL_STDERR}")
+      endif()
+
+      # Extract the Toolchain Search Path value and append Metal.xctoolchain
+      string(REGEX MATCH "Toolchain Search Path: ([^\n]+)" MATCH_RESULT "${FIND_METAL_OUT}")
+      set(METAL_TOOLCHAIN "${CMAKE_MATCH_1}/Metal.xctoolchain")
+    endif()
+
     # Set Metal compiler flags
-    set(METAL_FLAGS "-std=metal3.2" "-O2")
-    
+    set(METAL_FLAGS "-std=metal4.0" "-O2")
+
     # Output directory for compiled metallib
     set(METALLIB_OUTPUT_DIR "${CMAKE_BINARY_DIR}/metallib")
     file(MAKE_DIRECTORY ${METALLIB_OUTPUT_DIR})
@@ -18,73 +32,73 @@ function(compile_metal_shaders TARGET_NAME METAL_SOURCES EXTRA_INCLUDE_DIRS)
     set(AIR_FILES)
     set(METAL_FILES)
     set(HEADER_FILES)
-    
+
     foreach(SOURCE_FILE ${METAL_SOURCES})
         if(SOURCE_FILE MATCHES "\\.metal$")
             list(APPEND METAL_FILES ${SOURCE_FILE})
         elseif(SOURCE_FILE MATCHES "\\.h$")
             list(APPEND HEADER_FILES ${SOURCE_FILE})
         endif()
     endforeach()
-    
+
     foreach(METAL_FILE ${METAL_FILES})
         get_filename_component(METAL_NAME ${METAL_FILE} NAME_WE)
         set(AIR_FILE "${CMAKE_BINARY_DIR}/${METAL_NAME}.air")
-        
+
         # Include header files as dependencies
         set(ALL_DEPENDENCIES ${CMAKE_CURRENT_SOURCE_DIR}/${METAL_FILE})
         foreach(HEADER_FILE ${HEADER_FILES})
             list(APPEND ALL_DEPENDENCIES ${CMAKE_CURRENT_SOURCE_DIR}/${HEADER_FILE})
         endforeach()
-        
+
         add_custom_command(
             OUTPUT ${AIR_FILE}
-            COMMAND ${METAL_COMPILER} -sdk macosx metal ${METAL_FLAGS}
+            COMMAND "${METAL_TOOLCHAIN}/usr/bin/metal" ${METAL_FLAGS}
                     -c ${CMAKE_CURRENT_SOURCE_DIR}/${METAL_FILE}
                     -o ${AIR_FILE}
             DEPENDS ${ALL_DEPENDENCIES}
             COMMENT "Compiling Metal shader ${METAL_FILE} to ${AIR_FILE}"
             VERBATIM
         )
-        
+
         list(APPEND AIR_FILES ${AIR_FILE})
     endforeach()
-    
+
     # Link all .air files into a single .metallib
     set(METALLIB_FILE "${METALLIB_OUTPUT_DIR}/${TARGET_NAME}.metallib")
     add_custom_command(
         OUTPUT ${METALLIB_FILE}
-        COMMAND ${METAL_COMPILER} -sdk macosx metallib ${AIR_FILES}
+        COMMAND "${METAL_TOOLCHAIN}/usr/bin/metallib" ${AIR_FILES}
                 -o ${METALLIB_FILE}
         DEPENDS ${AIR_FILES}
         COMMENT "Linking Metal library ${METALLIB_FILE}"
         VERBATIM
     )
-    
+
     # Generate C++ header with embedded metallib data
     set(METALLIB_HEADER "${CMAKE_BINARY_DIR}/${TARGET_NAME}_metallib.h")
     set(METALLIB_TO_HEADER_SCRIPT "${CMAKE_CURRENT_SOURCE_DIR}/cmake/metallib_to_header.py")
-    
+
     add_custom_command(
         OUTPUT ${METALLIB_HEADER}
         COMMAND ${Python3_EXECUTABLE} ${METALLIB_TO_HEADER_SCRIPT} ${METALLIB_FILE} ${METALLIB_HEADER} ${TARGET_NAME}
         DEPENDS ${METALLIB_FILE} ${METALLIB_TO_HEADER_SCRIPT}
         COMMENT "Generating embedded Metal library header ${METALLIB_HEADER}"
         VERBATIM
     )
-    
+
     # Create a custom target for the metallib
     add_custom_target(${TARGET_NAME}_metallib ALL DEPENDS ${METALLIB_FILE} ${METALLIB_HEADER})
-    
+
     # Add dependency to main target
     add_dependencies(${TARGET_NAME} ${TARGET_NAME}_metallib)
-    
+
     # Add the generated header to include directories
     target_include_directories(${TARGET_NAME} PRIVATE ${CMAKE_BINARY_DIR})
-    
+
     # Pass the metallib header and namespace as compile definitions
-    target_compile_definitions(${TARGET_NAME} PRIVATE 
+    target_compile_definitions(${TARGET_NAME} PRIVATE
         EMBEDDED_METALLIB_HEADER="${TARGET_NAME}_metallib.h"
         EMBEDDED_METALLIB_NAMESPACE=${TARGET_NAME}_metal
     )
-endfunction()
+endfunction()

build2cmake/src/templates/metal/preamble.cmake

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.26)
 project({{name}} LANGUAGES CXX C OBJC OBJCXX)
 
-set(CMAKE_OSX_DEPLOYMENT_TARGET "15.0" CACHE STRING "Minimum macOS deployment version")
+set(CMAKE_OSX_DEPLOYMENT_TARGET "26.0" CACHE STRING "Minimum macOS deployment version")
 
 install(CODE "set(CMAKE_INSTALL_LOCAL_ONLY TRUE)" ALL_COMPONENTS)
 

flake.lock

@@ -10,6 +10,7 @@
   build2cmake,
   cmake,
   cmakeNvccThreadsHook,
+  cuda_nvcc,
   get-kernel-check,
   kernel-abi-check,
   ninja,
@@ -24,7 +25,7 @@
   xpuPackages,
 
   # Build inputs
-  apple-sdk_15,
+  apple-sdk_26,
   clr,
   oneapi-torch-dev,
   onednn-xpu,
@@ -96,6 +97,24 @@ stdenv.mkDerivation (prevAttrs: {
     } --ops-id ${rev} build.toml
   '';
 
+  preConfigure =
+    # This is a workaround for https://openradar.appspot.com/FB20389216 - even
+    # if the user downloaded the Metal toolchain, the mapping is not set up
+    # for the Nix build users. To make things worse, we cannot set up a mapping
+    # because the Nix build users do not have a writable home directory and
+    # showComponent/downloadComponent do not respect the HOME variable. So
+    # instead, we'll use showComponent (which will emit a lot of warnings due
+    # to the above) to grab the path of the Metal toolchain.
+    lib.optionalString metalSupport ''
+      METAL_PATH=$(${xcrunHost}/bin/xcrunHost xcodebuild -showComponent MetalToolchain 2> /dev/null | sed -rn "s/Toolchain Search Path: (.*)/\1/p")
+      if [ ! -d "$METAL_PATH" ]; then
+        >&2 echo "Cannot find Metal toolchain, use: xcodebuild -downloadComponent MetalToolchain"
+        exit 1
+      fi
+
+      cmakeFlagsArray+=("-DMETAL_TOOLCHAIN=$METAL_PATH/Metal.xctoolchain")
+    '';
+
   # hipify copies files, but its target is run in the CMake build and install
   # phases. Since some of the files come from the Nix store, this fails the
   # second time around.
@@ -115,7 +134,7 @@ stdenv.mkDerivation (prevAttrs: {
   ]
   ++ lib.optionals cudaSupport [
     cmakeNvccThreadsHook
-    cudaPackages.cuda_nvcc
+    cuda_nvcc
   ]
   ++ lib.optionals rocmSupport [
     clr
@@ -160,7 +179,7 @@ stdenv.mkDerivation (prevAttrs: {
     onednn-xpu
   ])
   ++ lib.optionals stdenv.hostPlatform.isDarwin [
-    apple-sdk_15
+    apple-sdk_26
   ]
   ++ extraDeps;
 
@@ -197,7 +216,8 @@ stdenv.mkDerivation (prevAttrs: {
   ]
   ++ lib.optionals metalSupport [
     # Use host compiler for Metal. Not included in the redistributable SDK.
-    (lib.cmakeFeature "METAL_COMPILER" "${xcrunHost}/bin/xcrunHost")
+    # Re-enable when the issue mentioned in preConfigure is solved.
+    #(lib.cmakeFeature "METAL_COMPILER" "${xcrunHost}/bin/xcrunHost")
   ];
 
   postInstall = ''

lib/torch-extension/arch.nix

@@ -6,6 +6,7 @@
   callPackage,
   stdenv,
   stdenvGlibc_2_27,
+  cudaPackages,
   rocmPackages,
   writeScriptBin,
   xpuPackages,
@@ -28,6 +29,12 @@ let
     }
   );
 
+  cuda_nvcc = cudaPackages.cuda_nvcc.override {
+    backendStdenv = cudaPackages.backendStdenv.override {
+      stdenv = effectiveStdenv;
+    };
+  };
+
   oneapi-torch-dev = xpuPackages.oneapi-torch-dev.override { stdenv = effectiveStdenv; };
   onednn-xpu = xpuPackages.onednn-xpu.override {
     inherit oneapi-torch-dev;
@@ -45,6 +52,7 @@ in
   mkExtension = callPackage ./arch.nix {
     inherit
       clr
+      cuda_nvcc
       oneapi-torch-dev
       onednn-xpu
       torch

lib/torch-extension/default.nix

@@ -3,10 +3,9 @@
   cudaSupport ? config.cudaSupport,
   fetchFromGitHub,
   overrideCC,
-  system,
   wrapBintoolsWith,
   wrapCCWith,
-  gcc12Stdenv,
+  gcc13Stdenv,
   stdenv,
   bintools-unwrapped,
   cudaPackages,
@@ -19,7 +18,7 @@ let
     repo = "nixpkgs";
     rev = "a9eb3eed170fa916e0a8364e5227ee661af76fde";
     hash = "sha256-1ycrr9HMrGA3ZDM8qmKcZICBupE5UShnIIhPRWdvAzA=";
-  }) { inherit system; };
+  }) { inherit (stdenv.hostPlatform) system; };
 
   glibc_2_27 = nixpkgs_20191230.glibc.overrideAttrs (prevAttrs: {
     # Slight adjustments for compatibility with modern nixpkgs:
@@ -64,10 +63,9 @@ let
           bintools = bintools-unwrapped;
           libc = newGlibc;
         };
-        libcxx = cc.lib;
       };
     in
     overrideCC stdenv compilerWrapped;
 
 in
-stdenvWith glibc_2_27 (if cudaSupport then cudaPackages.backendStdenv else gcc12Stdenv).cc.cc stdenv
+stdenvWith glibc_2_27 (if cudaSupport then cudaPackages.backendStdenv else gcc13Stdenv).cc.cc stdenv

pkgs/stdenv-glibc-2_27/default.nix

@@ -137,14 +137,14 @@
   }
 
   # Non-standard versions; not included in bundle builds.
-  {
-    torchVersion = "2.8";
-    cudaVersion = "12.4";
-    cxx11Abi = true;
-    systems = [
-      "x86_64-linux"
-      "aarch64-linux"
-    ];
-    sourceBuild = true;
-  }
+  #{
+  #  torchVersion = "2.8";
+  #  cudaVersion = "12.4";
+  #  cxx11Abi = true;
+  #  systems = [
+  #    "x86_64-linux"
+  #    "aarch64-linux"
+  #  ];
+  #  sourceBuild = true;
+  #}
 ]