kernel: allow disabling multicast routing support

Multicast routing support is not needed in most setups, and increases the
size of the kernel considerably (>10K after LZMA). Add a config switch to
allow disabling it.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

config/Config-kernel.in

@@ -607,6 +607,17 @@ config KERNEL_SECCOMP
 		help
 		  Build kernel with support for seccomp.
 
+#
+# IPv4 configuration
+#
+
+config KERNEL_IP_MROUTE
+	bool "Enable IPv4 multicast routing"
+	default y
+	help
+	  Multicast routing requires a multicast routing daemon in
+	  addition to kernel support.
+
 #
 # IPv6 configuration
 #
@@ -623,7 +634,11 @@ if KERNEL_IPV6
 		def_bool y
 
 	config KERNEL_IPV6_MROUTE
-		def_bool y
+		bool "Enable IPv6 multicast routing"
+		default y
+		help
+		  Multicast routing requires a multicast routing daemon in
+		  addition to kernel support.
 
 	config KERNEL_IPV6_PIMSM_V2
 		def_bool n

target/linux/generic/config-3.18

@@ -1630,7 +1630,7 @@ CONFIG_IPW2200_MONITOR=y
 CONFIG_IP_ADVANCED_ROUTER=y
 # CONFIG_IP_DCCP is not set
 # CONFIG_IP_FIB_TRIE_STATS is not set
-CONFIG_IP_MROUTE=y
+# CONFIG_IP_MROUTE is not set
 CONFIG_IP_MROUTE_MULTIPLE_TABLES=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_MULTIPLE_TABLES=y

target/linux/generic/config-4.14

@@ -2032,7 +2032,7 @@ CONFIG_IPW2200_MONITOR=y
 CONFIG_IP_ADVANCED_ROUTER=y
 # CONFIG_IP_DCCP is not set
 # CONFIG_IP_FIB_TRIE_STATS is not set
-CONFIG_IP_MROUTE=y
+# CONFIG_IP_MROUTE is not set
 CONFIG_IP_MROUTE_MULTIPLE_TABLES=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_MULTIPLE_TABLES=y

target/linux/generic/config-4.4

@@ -1710,7 +1710,7 @@ CONFIG_IPW2200_MONITOR=y
 CONFIG_IP_ADVANCED_ROUTER=y
 # CONFIG_IP_DCCP is not set
 # CONFIG_IP_FIB_TRIE_STATS is not set
-CONFIG_IP_MROUTE=y
+# CONFIG_IP_MROUTE is not set
 CONFIG_IP_MROUTE_MULTIPLE_TABLES=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_MULTIPLE_TABLES=y

target/linux/generic/config-4.9

@@ -1931,7 +1931,7 @@ CONFIG_IPW2200_MONITOR=y
 CONFIG_IP_ADVANCED_ROUTER=y
 # CONFIG_IP_DCCP is not set
 # CONFIG_IP_FIB_TRIE_STATS is not set
-CONFIG_IP_MROUTE=y
+# CONFIG_IP_MROUTE is not set
 CONFIG_IP_MROUTE_MULTIPLE_TABLES=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_MULTIPLE_TABLES=y