[PATCH 1/1] spdx3: Add optional kernel configuration export to build_parameter for virtual/kernel

[Kamel Bouhara <kamel.bouhara@bootlin.com>]

Enhances SPDX Document by extracting kernel build-time configuration settings from '${B}/.config'.

Each CONFIG_* line is parsed and exported as a DictionaryEntry in the build_Build.build_parameter
section of the SPDX document. This provides better visibility into kernel build behavior and
configuration, in alignment with the SPDX3 metadata model.

The feature is gated by a new tunable variable:

    SPDX_INCLUDE_KERNEL_CONFIG (default: "1")

Setting this to "0" disables exporting the kernel configuration, which may be useful to improve
performance or reduce the size of generated SPDX documents.

Example:

    CONFIG_FOO=y  →  { key: "CONFIG_FOO", value: "y" }

This complements existing metadata export features and enables a more complete audit trail of how
the kernel is built within a given build.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 meta/classes/create-spdx-3.0.bbclass |  6 ++++++
 meta/lib/oe/spdx30_tasks.py          | 32 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/meta/classes/create-spdx-3.0.bbclass b/meta/classes/create-spdx-3.0.bbclass
index c0a5436ad6..cdb9422f37 100644
--- a/meta/classes/create-spdx-3.0.bbclass
+++ b/meta/classes/create-spdx-3.0.bbclass
@@ -50,6 +50,12 @@ SPDX_INCLUDE_TIMESTAMPS[doc] = "Include time stamps in SPDX output. This is \
     useful if you want to know when artifacts were produced and when builds \
     occurred, but will result in non-reproducible SPDX output"
 
+SPDX_INCLUDE_KERNEL_CONFIG ??= "1"
+SPDX_INCLUDE_KERNEL_CONFIG[doc] = "If set to '1', the .config file for the kernel will be parsed \
+and each CONFIG_* value will be included in the Build.build_parameter list as DictionaryEntry \
+items. Set to '0' to disable exporting kernel configuration to improve performance or reduce \
+SPDX document size."
+
 SPDX_IMPORTS ??= ""
 SPDX_IMPORTS[doc] = "SPDX_IMPORTS is the base variable that describes how to \
     reference external SPDX ids. Each import is defined as a key in this \
diff --git a/meta/lib/oe/spdx30_tasks.py b/meta/lib/oe/spdx30_tasks.py
index c352dab152..f87d079cb0 100644
--- a/meta/lib/oe/spdx30_tasks.py
+++ b/meta/lib/oe/spdx30_tasks.py
@@ -18,6 +18,28 @@ from contextlib import contextmanager
 from datetime import datetime, timezone
 from pathlib import Path
 
+def parse_kernel_config(config_path):
+    entries = []
+    if not os.path.exists(config_path):
+        bb.warn(f"Kernel config file not found at: {config_path}")
+        return entries
+
+    try:
+        with open(config_path, 'r') as f:
+            for line in f:
+                line = line.strip()
+                if not line or line.startswith("#"):
+                    continue
+                if "=" in line:
+                    key, value = line.split("=", 1)
+                    entries.append(oe.spdx30.DictionaryEntry(
+                        key=key,
+                        value=value.strip('"')
+                    ))
+        bb.note(f"Parsed {len(entries)} kernel config entries from {config_path}")
+    except Exception as e:
+        bb.error(f"Failed to parse kernel config file: {e}")
+    return entries
 
 def walk_error(err):
     bb.error(f"ERROR walking {err.filename}: {err}")
@@ -495,6 +517,8 @@ def create_spdx(d):
 
     build_objset.doc.rootElement.append(build)
 
+    build.build_parameter = []
+
     build_objset.set_is_native(is_native)
 
     for var in (d.getVar("SPDX_CUSTOM_ANNOTATION_VARS") or "").split():
@@ -815,6 +839,14 @@ def create_spdx(d):
             sorted(list(build_inputs)) + sorted(list(debug_source_ids)),
         )
 
+    if d.getVar("SPDX_INCLUDE_KERNEL_CONFIG", True) != "0":
+        if "virtual/kernel" in (d.getVar("PROVIDES") or "").split():
+            bb.note("Detected virtual/kernel provider, extracting kernel configuration")
+            config_path = d.expand("${B}/.config")
+            kernel_params = parse_kernel_config(config_path)
+            if kernel_params:
+                build.build_parameter.extend(kernel_params)
+
     oe.sbom30.write_recipe_jsonld_doc(d, build_objset, "recipes", deploydir)
 
 
-- 
2.43.0