commit 76b969a66e91f790cebdcc45a30aef0a0a910d6b
Author: KV2773 <kushal.verma1@ibm.com>
Date:   Thu Aug 13 12:33:52 2026 -0500

    AIX support

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 791e24bf0..bd992469c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -556,11 +556,26 @@ if(ONNX_BUILD_PYTHON)
       GIT_REPOSITORY ${_nanobind_URL}
       GIT_TAG v${_nanobind_VERSION}
       GIT_SHALLOW TRUE
+      PATCH_COMMAND git checkout . && git apply --whitespace=fix --ignore-space-change --ignore-whitespace ${CMAKE_CURRENT_SOURCE_DIR}/cmake/external/nanobind_aix.patch
     )
     FetchContent_MakeAvailable(nanobind)
   endif()
 
-  # Configure nanobind: https://nanobind.readthedocs.io/en/latest/api_cmake.html
+if (CMAKE_SYSTEM_NAME STREQUAL "AIX")
+  nanobind_add_module(
+    onnx_cpp2py_export
+    NB_STATIC NB_DOMAIN onnx STABLE_ABI FREE_THREADED 
+    "${ONNX_ROOT}/onnx/cpp2py_export.cc")
+target_link_libraries(onnx_cpp2py_export PRIVATE 
+onnx
+)
+
+   target_link_options(onnx_cpp2py_export PRIVATE
+    "-Wl,-bkeepfile:$<TARGET_FILE:onnx>"  # Keeps all objects inside libonnx.a alive
+    "-Wl,-bexpall"
+)
+else()
+    # Configure nanobind: https://nanobind.readthedocs.io/en/latest/api_cmake.html
   nanobind_add_module(
     onnx_cpp2py_export
     NB_STATIC NB_DOMAIN onnx STABLE_ABI FREE_THREADED LTO
@@ -568,8 +583,8 @@ if(ONNX_BUILD_PYTHON)
   # Force-load the whole (static) archive so the operator schemas' static
   # initializers are not dropped as apparently-unused. $<LINK_LIBRARY:WHOLE_ARCHIVE,...>
   # is the portable --whole-archive / -force_load / /WHOLEARCHIVE spelling.
-  target_link_libraries(onnx_cpp2py_export PRIVATE
-    $<LINK_LIBRARY:WHOLE_ARCHIVE,onnx>)
+    target_link_libraries(onnx_cpp2py_export PRIVATE $<LINK_LIBRARY:WHOLE_ARCHIVE,onnx>)
+endif()
 endif()
 
 add_onnx_compile_options(onnx_proto)
diff --git a/cmake/external/nanobind_aix.patch b/cmake/external/nanobind_aix.patch
new file mode 100644
index 000000000..d78030ace
--- /dev/null
+++ b/cmake/external/nanobind_aix.patch
@@ -0,0 +1,28 @@
+diff --git a/cmake/nanobind-config.cmake b/cmake/nanobind-config.cmake
+index 7684035..469a7e9 100644
+--- a/cmake/nanobind-config.cmake
++++ b/cmake/nanobind-config.cmake
+@@ -219,7 +219,7 @@ function (nanobind_build_library TARGET_NAME)
+     nanobind_lto(${TARGET_NAME})
+ 
+     nanobind_strip(${TARGET_NAME})
+-  elseif(NOT WIN32 AND NOT APPLE)
++  elseif(NOT WIN32 AND NOT APPLE AND NOT AIX)
+     target_compile_options(${TARGET_NAME} PUBLIC $<${NB_OPT_SIZE}:-ffunction-sections -fdata-sections>)
+     target_link_options(${TARGET_NAME} PUBLIC $<${NB_OPT_SIZE}:-Wl,--gc-sections>)
+   endif()
+diff --git a/src/nb_internals.h b/src/nb_internals.h
+index cb15de8..c2f50db 100644
+--- a/src/nb_internals.h
++++ b/src/nb_internals.h
+@@ -31,6 +31,10 @@
+ #  define NB_THREAD_LOCAL __thread
+ #endif
+ 
++#if defined(_AIX) && defined(func_data)
++#undef func_data
++#endif
++
+ #if PY_VERSION_HEX >= 0x030A0000
+ #  define NB_TPFLAGS_IMMUTABLETYPE Py_TPFLAGS_IMMUTABLETYPE
+ #else

diff --git a/CMakeLists.txt b/CMakeLists.txt
index bd992469c..6a6ad8b97 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -517,7 +517,11 @@ add_dependencies(onnx_proto onnx_proto_gen)
 add_library(onnx $<TARGET_OBJECTS:onnx_proto>)
 add_subdirectory(onnx)
 add_dependencies(onnx onnx_proto)
+if (CMAKE_SYSTEM_NAME MATCHES "AIX")
+set_target_properties(onnx PROPERTIES CXX_VISIBILITY_PRESET default)
+else()
 set_target_properties(onnx PROPERTIES CXX_VISIBILITY_PRESET hidden)
+endif()
 add_onnx_global_defines(onnx)
 
 if(ONNX_BUILD_PYTHON)





diff --git a/cmake/unittest.cmake b/cmake/unittest.cmake
index f13e5e16..b72c2544 100644
--- a/cmake/unittest.cmake
+++ b/cmake/unittest.cmake
@@ -23,6 +23,15 @@ set(test_src
 add_executable(${UT_NAME} ${test_src})
 find_package(Threads REQUIRED)
 target_link_libraries(${UT_NAME} PRIVATE onnx Threads::Threads)
+
+if(CMAKE_SYSTEM_NAME STREQUAL "AIX")
+target_link_options(onnx_gtests PRIVATE 
+    "-Wl,-bkeepfile:CMakeFiles/onnx_gtests.dir/onnx/test/cpp/checker_test.cc.o"
+    "-Wl,-bkeepfile:CMakeFiles/onnx_gtests.dir/onnx/test/cpp/shape_inference_test.cc.o"
+    "-Wl,-bkeepfile:CMakeFiles/onnx_gtests.dir/onnx/test/cpp/utf8_conversion_test.cc.o"
+)
+endif()
+
 if(TARGET GTest::gtest)
   target_link_libraries(${UT_NAME} PRIVATE GTest::gtest)
 else()