tools: add support for merge_config

Usage example:
./tools/merge_config.py -o defconfig .config1 .config2

Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>

Documentation/quickstart/configuring.rst

@@ -140,3 +140,13 @@ The default header file search path includes:
    CONFIG_XXX2=y
    #include "configs/system.config"
    #include "configs/net.config"
+
+Merge configuration
+--------------------------
+
+Multiple config fragments can be merged manually using the tools/merge_config.py script.
+
+.. code-block:: console
+
+   $ cd nuttx
+   $ ./tools/merge_config.py -o defconfig .config1 .config2

tools/merge_config.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+############################################################################
+# tools/merge_config.py
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you 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.
+#
+############################################################################
+
+import argparse
+import os
+
+try:
+    from kconfiglib import Kconfig
+except ModuleNotFoundError:
+    print("Please execute the following command to install dependencies:")
+    print("pip install kconfiglib")
+    exit()
+
+script_path = os.path.split(os.path.realpath(__file__))[0]
+topdir = os.path.join(script_path, "..")
+kconfig_path = os.path.join(topdir, "Kconfig")
+
+# Set environment variables
+
+os.environ["BINDIR"] = os.path.join(topdir)
+os.environ["APPSDIR"] = os.path.join(topdir, "../apps")
+os.environ["APPSBINDIR"] = os.path.join(topdir, "../apps")
+
+
+def merge_configs(output_file, input_files):
+    kconf = Kconfig(kconfig_path, suppress_traceback=True)
+
+    kconf.warn_assign_undef = True
+    kconf.warn_assign_override = False
+    kconf.warn_assign_redun = False
+
+    for input_file in input_files:
+        print(kconf.load_config(input_file, replace=False))
+
+    # Save the merged configuration to the output file
+
+    kconf.write_min_config(output_file)
+    print(f"Configuration successfully merged to {output_file}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Merge Kconfig configuration files")
+    parser.add_argument(
+        "-o", "--output", required=True, help="Output merged configuration file"
+    )
+    parser.add_argument(
+        "input_files", nargs="+", help="List of input configuration files"
+    )
+    args = parser.parse_args()
+
+    merge_configs(args.output, args.input_files)