[PATCH v4 1/6] docs: kdoc: add GNU Make detection

The Sphinx dependency checker and build wrapper need to select a GNU
Make executable that meets the minimum supported version. Keep the version
parsing and command selection in a common module so both tools use
identical behavior.

Signed-off-by: Chen Miao <[email protected]>
---
 tools/lib/python/kdoc/gmake_detect.py | 62 +++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 tools/lib/python/kdoc/gmake_detect.py

diff --git a/tools/lib/python/kdoc/gmake_detect.py b/tools/lib/python/kdoc/gmake_detect.py
new file mode 100644
index 000000000..5c0a28bc7
--- /dev/null
+++ b/tools/lib/python/kdoc/gmake_detect.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2026 Chen Miao <[email protected]>
+
+"""Detect a supported GNU Make executable."""
+
+import re
+import shutil
+import subprocess
+import sys
+
+from kdoc.python_version import PythonVersion
+
+
+MIN_GMAKE_VERSION = PythonVersion("4.0").version
+
+
+def get_gmake_version(cmd):
+    """Return the GNU Make version for *cmd*, or ``None`` otherwise."""
+    if not cmd:
+        return None
+
+    kwargs = {}
+    if sys.version_info < (3, 7):
+        kwargs["universal_newlines"] = True
+    else:
+        kwargs["text"] = True
+
+    try:
+        result = subprocess.run(
+            [cmd, "--version"],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            check=True,
+            **kwargs,
+        )
+    except (OSError, subprocess.CalledProcessError):
+        return None
+
+    match = re.search(
+        r"^GNU Make\s+([0-9]+(?:\.[0-9]+)*)", result.stdout, re.MULTILINE
+    )
+    if not match:
+        return None
+
+    return PythonVersion.parse_version(match.group(1))
+
+
+def find_gmake(make=None):
+    """Return the first GNU Make 4.0+ from MAKE, gmake, or make."""
+    candidates = (
+        make,
+        shutil.which("gmake"),
+        shutil.which("make"),
+    )
+
+    for cmd in candidates:
+        version = get_gmake_version(cmd)
+        if version and version >= MIN_GMAKE_VERSION:
+            return cmd
+
+    return None
-- 
2.50.1 (Apple Git-155)