added support for building baremetal on macOS

CMakeLists.txt

@@ -46,12 +46,23 @@ list(APPEND ARM_ARCH_MAJOR_LIST 8 9)
 list(APPEND ACS_LIST "bsa" "sbsa" "pc_bsa")
 
 ###
-set(CROSS_COMPILE $ENV{CROSS_COMPILE})
-# Set default only if not defined externally
-if(NOT DEFINED CROSS_COMPILE)
-    message(FATAL_ERROR "CROSS_COMPILE not defined. Exiting.")
+# Prefer the toolchain file to validate and set `CROSS_COMPILE`.
+# If no toolchain file is provided, require `CROSS_COMPILE` from the
+# environment to support local cross-configures.
+if(NOT DEFINED CMAKE_TOOLCHAIN_FILE)
+    if(NOT DEFINED CROSS_COMPILE)
+        set(CROSS_COMPILE $ENV{CROSS_COMPILE})
+    endif()
+
+    if(NOT DEFINED CROSS_COMPILE OR "${CROSS_COMPILE}" STREQUAL "")
+        message(FATAL_ERROR "CROSS_COMPILE not defined. Please set CROSS_COMPILE or use -DCMAKE_TOOLCHAIN_FILE=<path>.")
+    endif()
 endif()
 
+# NOTE: cross-toolchain selection is handled by an explicit toolchain file
+# (`tools/cmake/toolchain/arm-none-elf-toolchain.cmake`). Users should
+# configure with `-DCMAKE_TOOLCHAIN_FILE=...` to avoid host-specific flags.
+
 # Check for valid targets
 _get_sub_dir_list(TARGET_LIST ${ROOT_DIR}/pal/baremetal/target/)
 if(NOT DEFINED TARGET)
@@ -62,8 +73,6 @@ endif()
 
 if(NOT ${TARGET} IN_LIST TARGET_LIST)
     message(FATAL_ERROR "[ACS] : Error: Unspported value for -DTARGET=, supported targets are : ${TARGET_LIST}")
-else()
-    message(STATUS "[ACS] : TARGET is set to ${TARGET}")
 endif()
 
 # Check for ARM_ARCH_MAJOR
@@ -101,24 +110,25 @@ foreach(clean_item ${CLEAN_LIST})
 endforeach()
 ###
 
-# Custom targets to trigger bsa and sbsa builds
-add_custom_target(bsa
-    COMMAND ${CMAKE_COMMAND} -DACS=bsa -DTARGET=${TARGET} -S ${CMAKE_SOURCE_DIR} -B ${CMAKE_BINARY_DIR}/bsa_build
-    COMMAND ${CMAKE_COMMAND} --build ${CMAKE_BINARY_DIR}/bsa_build
-)
-
-add_custom_target(sbsa
-    COMMAND ${CMAKE_COMMAND} -DACS=sbsa -DTARGET=${TARGET} -S ${CMAKE_SOURCE_DIR} -B ${CMAKE_BINARY_DIR}/sbsa_build
-    COMMAND ${CMAKE_COMMAND} --build ${CMAKE_BINARY_DIR}/sbsa_build
-)
+# Generate per-ACS custom targets and an aggregate target
+foreach(_acs IN LISTS ACS_LIST)
+    add_custom_target(${_acs}
+        COMMAND ${CMAKE_COMMAND} -DACS=${_acs} -DTARGET=${TARGET} -DCMAKE_OSX_ARCHITECTURES= -DCMAKE_TOOLCHAIN_FILE=${ROOT_DIR}/tools/cmake/toolchain/arm-none-elf-toolchain.cmake -S ${CMAKE_SOURCE_DIR} -B ${CMAKE_BINARY_DIR}/${_acs}_build
+        COMMAND ${CMAKE_COMMAND} --build ${CMAKE_BINARY_DIR}/${_acs}_build
+    )
+endforeach()
 
-add_custom_target(pc_bsa
-    COMMAND ${CMAKE_COMMAND} -DACS=pc_bsa -DTARGET=${TARGET} -S ${CMAKE_SOURCE_DIR} -B ${CMAKE_BINARY_DIR}/pc_bsa_build
-    COMMAND ${CMAKE_COMMAND} --build ${CMAKE_BINARY_DIR}/pc_bsa_build
+add_custom_target(acs_all
+    DEPENDS ${ACS_LIST}
 )
 
 if(ACS IN_LIST ACS_LIST)
-    message(STATUS "[ACS] : ACS is set to ${ACS}")
+    message(STATUS "[ACS] : ACS is set to ${ACS}, and TAREGT to ${TARGET} based on configuration")
+    message(STATUS "[ACS] : You can change overide configuration using -DACS=<value> or -DTARGET=<value>")
+    message(STATUS "[ACS] : Supported values are ACS: ${ACS_LIST}, TARGET: ${TARGET_LIST}")
+    message(STATUS "[ACS] : Example - cmake --preset baremetal -DACS=sbsa -DTARGET=RDV3")
+    message(STATUS "[ACS] : To build using cmake - 'cmake --build --preset baremetal")
+    message(STATUS "[ACS] : To build using make - 'cd build; make bsa' - here TARGET reconfigure not required, all targets supported")
     add_subdirectory(${ROOT_DIR}/tools/cmake/infra)
 endif()
 

CMakePresets.json

@@ -0,0 +1,25 @@
+{
+    "version": 3,
+    "cmakeMinimumRequired": { "major": 3, "minor": 19, "patch": 0 },
+    "configurePresets": [
+    {
+        "name": "baremetal",
+        "displayName": "Configure: aarch64-none-elf (baremetal)",
+        "generator": "Unix Makefiles",
+        "binaryDir": "${sourceDir}/build",
+        "cacheVariables": {
+        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/tools/cmake/toolchain/arm-none-elf-toolchain.cmake",
+        "CMAKE_OSX_ARCHITECTURES": "",
+        "ACS": "bsa",
+        "TARGET": "RDN2"
+        }
+    }
+    ],
+    "buildPresets": [
+    {
+        "name": "baremetal",
+        "configurePreset": "baremetal",
+        "jobs": 8
+    }
+    ]
+}

tools/cmake/toolchain/arm-none-elf-toolchain.cmake

@@ -0,0 +1,44 @@
+## @file
+ # Copyright (c) 2025, Arm Limited or its affiliates. All rights reserved.
+ # SPDX-License-Identifier : Apache-2.0
+ #
+ # Licensed under the Apache License, Version 2.0 (the "License");
+ # you may not use this file except in compliance with the License.
+ # You may obtain a copy of the License at
+ #
+ #  http://www.apache.org/licenses/LICENSE-2.0
+ #
+ # Unless required by applicable law or agreed to in writing, software
+ # distributed under the License is distributed on an "AS IS" BASIS,
+ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ # See the License for the specific language governing permissions and
+ # limitations under the License.
+ ##
+
+# Minimal toolchain for aarch64-none-elf cross builds
+# Set system name early to avoid passing -arch compiler options on macOS
+set(CMAKE_SYSTEM_NAME Generic CACHE STRING "Cross compile system" FORCE)
+
+# Disable -arch flags on macOS
+set(CMAKE_OSX_ARCHITECTURES "" CACHE STRING "Disable -arch flags for cross compile" FORCE)
+
+# Pull CROSS_COMPILE from environment if not provided
+if(NOT DEFINED CROSS_COMPILE)
+    if(DEFINED ENV{CROSS_COMPILE})
+        set(CROSS_COMPILE $ENV{CROSS_COMPILE})
+    endif()
+endif()
+
+if(NOT DEFINED CROSS_COMPILE OR "${CROSS_COMPILE}" STREQUAL "")
+    message(FATAL_ERROR "CROSS_COMPILE not defined in environment. Please set CROSS_COMPILE to your toolchain prefix.")
+endif()
+
+set(CMAKE_C_COMPILER "${CROSS_COMPILE}gcc" CACHE FILEPATH "C compiler" FORCE)
+set(CMAKE_ASM_COMPILER "${CMAKE_C_COMPILER}" CACHE FILEPATH "ASM compiler" FORCE)
+set(CMAKE_AR "${CROSS_COMPILE}ar" CACHE FILEPATH "Archiver" FORCE)
+set(CMAKE_OBJCOPY "${CROSS_COMPILE}objcopy" CACHE FILEPATH "Objcopy" FORCE)
+set(CMAKE_OBJDUMP "${CROSS_COMPILE}objdump" CACHE FILEPATH "Objdump" FORCE)
+set(CMAKE_RANLIB "${CROSS_COMPILE}ranlib" CACHE FILEPATH "Ranlib" FORCE)
+
+# Ensure baremetal sources get appropriate platform macro
+add_definitions(-DTARGET_BAREMETAL)

tools/cmake/toolchain/common.cmake

@@ -52,7 +52,15 @@ endif()
 set(LINKER_FILE "${ROOT_DIR}/tools/cmake/toolchain/linker.cmake")
 
 set(CROSS_COMPILE ${CROSS_COMPILE} CACHE INTERNAL "CROSS_COMPILE is set to ${CROSS_COMPILE}" FORCE)
-set(CMAKE_C_COMPILER ${CMAKE_C_COMPILER} CACHE INTERNAL "CMAKE_C_COMPILER is set to ${CMAKE_C_COMPILER}" FORCE)
+# Only populate the cache entry for `CMAKE_C_COMPILER` if it isn't
+# already set by a toolchain file or the cache. Avoid FORCE to prevent
+# overwriting a value the user or toolchain provided.
+set(CMAKE_C_COMPILER ${CMAKE_C_COMPILER} CACHE INTERNAL "CMAKE_C_COMPILER is set to ${CMAKE_C_COMPILER}" FORCE) 
 
-include(${COMPILER_FILE})
-include(${LINKER_FILE})
+if(DEFINED COMPILER_FILE)
+    include(${COMPILER_FILE})
+endif()
+
+if(DEFINED LINKER_FILE)
+    include(${LINKER_FILE})
+endif()

tools/cmake/toolchain/gnuarm.cmake

@@ -32,6 +32,8 @@ else()
     set(TARGET_SWITCH "-march=armv${ARM_ARCH_MAJOR}.${ARM_ARCH_MINOR}-a+sve+profile")
 endif()
 
+message(STATUS "[ACS] : TARGET_SWITCH is set to ${TARGET_SWITCH}")
+
 if(${ENABLE_PIE})
     set(COMPILE_PIE_SWITCH "-fpie")
     add_definitions(-DENABLE_PIE)