insmod: clarify module_name / file_name distinction

include/usage.h

@@ -1864,8 +1864,12 @@
      "\ninotifyd waits for PROG to exit." \
      "\nWhen x event happens for all FILEs, inotifyd exits" \
 
+/* 2.6 style insmod has no options and required filename
+ * (not module name - .ko can't be omitted) */
 #define insmod_trivial_usage \
-	USE_FEATURE_2_4_MODULES("[OPTION]... ") "MODULE [symbol=value]..."
+	USE_FEATURE_2_4_MODULES("[OPTION]... MODULE ") \
+	SKIP_FEATURE_2_4_MODULES("FILE ") \
+	"[symbol=value]..."
 #define insmod_full_usage "\n\n" \
        "Load the specified kernel modules into the kernel" \
 	USE_FEATURE_2_4_MODULES( "\n" \

modutils/insmod.c

@@ -16,6 +16,14 @@ int insmod_main(int argc UNUSED_PARAM, char **argv)
 	char *filename;
 	int rc;
 
+	/* Compat note:
+	 * 2.6 style insmod has no options and required filename
+	 * (not module name - .ko can't be omitted).
+	 * 2.4 style insmod can take module name without .ko
+	 * and performs module search in default directories
+	 * or in $MODPATH.
+	 */
+
 	USE_FEATURE_2_4_MODULES(
 		getopt32(argv, INSMOD_OPTS INSMOD_ARGS);
 		argv += optind - 1;

modutils/modutils-24.c

@@ -3810,7 +3810,7 @@ static void print_load_map(struct obj_file *f UNUSED_PARAM)
 }
 #endif
 
-int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options UNUSED_PARAM)
+int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options)
 {
 	int k_crcs;
 	unsigned long m_size;