Create menu entry to select device creation method

Four methods for the creation of device files in /dev are now
proposed:

 - static method uses device table as before
 - devtmpfs method enables this feature in kernel
 - mdev method adds mdev starting script to the file system
    and selects mdev itself for installation
 - udev method selects udev for installation

All dynamic methods are based on devtmpfs, so one doesn't need to care
about /dev folder.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

fs/Config.in

@@ -15,13 +15,34 @@ config BR2_ROOTFS_POST_BUILD_SCRIPT
 	  only argument. Make sure the exit code of that script is 0,
 	  otherwise make will stop after calling it.
 
+choice
+	prompt "/dev management"
+	default BR2_ROOTFS_DEVICE_CREATION_STATIC
+
+config BR2_ROOTFS_DEVICE_CREATION_STATIC
+	bool "Static using device table"
+
+config BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_DEVTMPFS
+	bool "Dynamic using devtmpfs only"
+
+config BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV
+	bool "Dynamic using mdev"
+	select BR2_PACKAGE_BUSYBOX
+
+config BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_UDEV
+	bool "Dynamic using udev"
+	select BR2_PACKAGE_UDEV
+
+endchoice
+
 config BR2_ROOTFS_DEVICE_TABLE
-       string "Path to the device table"
-       default "target/generic/device_table.txt"
-       help
-         Specify the location of a device table, that will be passed
-         to the makedevs utility to create all the special device
-         files in the target filesystem.
+	string "Path to the device table"
+	depends on BR2_ROOTFS_DEVICE_CREATION_STATIC
+	default "target/generic/device_table.txt"
+	help
+	  Specify the location of a device table, that will be passed
+	  to the makedevs utility to create all the special device
+	  files in the target filesystem.
 
 choice
 	prompt "Root FS skeleton"