From e75149e46c71f95d6f44056dcc538e9e9dc2f353 Mon Sep 17 00:00:00 2001
From: Prasad Shetty <11435405+prashymh@users.noreply.github.com>
Date: Sun, 28 Dec 2025 19:09:16 +0530
Subject: [PATCH] added support for building baremetal on macOS

also refactored the cmakefiles to make the build process easy
with presets, which helps reduces the commands needed to configrue
and build using cmake, also refactored to reduce some redundant code
addtional help added into cmake commands to configure and build
---
 CMakeLists.txt                                | 50 +++++++++++--------
 CMakePresets.json                             | 25 ++++++++++
 .../toolchain/arm-none-elf-toolchain.cmake    | 44 ++++++++++++++++
 tools/cmake/toolchain/common.cmake            | 14 ++++--
 tools/cmake/toolchain/gnuarm.cmake            |  2 +
 5 files changed, 112 insertions(+), 23 deletions(-)
 create mode 100644 CMakePresets.json
 create mode 100644 tools/cmake/toolchain/arm-none-elf-toolchain.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2128ea71..a3dc3cfd 100644
--- a/CMakeLists.txt
+++ b/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()
 
diff --git a/CMakePresets.json b/CMakePresets.json
new file mode 100644
index 00000000..a54fbc76
--- /dev/null
+++ b/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
+    }
+    ]
+}
\ No newline at end of file
diff --git a/tools/cmake/toolchain/arm-none-elf-toolchain.cmake b/tools/cmake/toolchain/arm-none-elf-toolchain.cmake
new file mode 100644
index 00000000..6cbda351
--- /dev/null
+++ b/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)
diff --git a/tools/cmake/toolchain/common.cmake b/tools/cmake/toolchain/common.cmake
index 533ac31e..70fe86c5 100644
--- a/tools/cmake/toolchain/common.cmake
+++ b/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()
diff --git a/tools/cmake/toolchain/gnuarm.cmake b/tools/cmake/toolchain/gnuarm.cmake
index b4e2e29d..472c2ce1 100644
--- a/tools/cmake/toolchain/gnuarm.cmake
+++ b/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)