set either of these variables to "nc". Input and output can be
switched independently.
+CONFIG_NETCONSOLE_BUFFER_SIZE - Override the default buffer size
+
We use an environment variable 'ncip' to set the IP address and the
port of the destination. The format is <ip_addr>:<port>. If <port> is
omitted, the value of 6666 is used. If the env var doesn't exist, the