#Device Nodes
device nodes can be created in several ways:
devtmpfs: The device node is created when the device driver registers a new device interface using a base name supplied by the driver (ttyAMA) and an instance number.
udev or mdev (without devtmpfs): Essentially the same as with devtmpfs, except that a user space daemon program has to extract the device name from sysfs and create the node.
mknod: If you are using static device nodes, they are created manually using mknod.