kheaders: explain why include/config/autoconf.h is excluded from md5sum
This comment block explains why include/generated/compile.h is omitted,
but nothing about include/generated/autoconf.h, which might be more
difficult to understand. Add more comments.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
index dc5744b..e13ca84 100755
--- a/kernel/gen_kheaders.sh
+++ b/kernel/gen_kheaders.sh
@@ -32,8 +32,15 @@
all_dirs="$all_dirs $dir_list"
# include/generated/compile.h is ignored because it is touched even when none
-# of the source files changed. This causes pointless regeneration, so let us
-# ignore them for md5 calculation.
+# of the source files changed.
+#
+# When Kconfig regenerates include/generated/autoconf.h, its timestamp is
+# updated, but the contents might be still the same. When any CONFIG option is
+# changed, Kconfig touches the corresponding timestamp file include/config/*.h.
+# Hence, the md5sum detects the configuration change anyway. We do not need to
+# check include/generated/autoconf.h explicitly.
+#
+# Ignore them for md5 calculation to avoid pointless regeneration.
headers_md5="$(find $all_dirs -name "*.h" |
grep -v "include/generated/compile.h" |
grep -v "include/generated/autoconf.h" |