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- In U-Boot, we implemented the networked console via the standard
- "devices" mechanism, which means that you can switch between the
- serial and network input/output devices by adjusting the 'stdin' and
- 'stdout' environment variables. To switch to the networked console,
- 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
- broadcast address and port 6666 are used. If it is set to an IP
- address of 0 (or 0.0.0.0) then no messages are sent to the network.
- The source / listening port can be configured separately by setting
- the 'ncinport' environment variable and the destination port can be
- configured by setting the 'ncoutport' environment variable.
- For example, if your server IP is 192.168.1.1, you could use:
- => setenv nc 'setenv stdout nc;setenv stdin nc'
- => setenv ncip 192.168.1.1
- => saveenv
- => run nc
- On the host side, please use this script to access the console:
- tools/netconsole <ip> [port]
- The script uses netcat to talk to the board over UDP. It requires you to
- specify the target IP address (or host name, assuming DNS is working). The
- script can be interrupted by pressing ^T (CTRL-T).
- Be aware that in some distributives (Fedora Core 5 at least)
- usage of nc has been changed and -l and -p options are considered
- as mutually exclusive. If nc complains about options provided,
- you can just remove the -p option from the script.
- It turns out that 'netcat' cannot be used to listen to broadcast
- packets. We developed our own tool 'ncb' (see tools directory) that
- listens to broadcast packets on a given port and dumps them to the
- standard output. It will be built when compiling for a board which
- has CONFIG_NETCONSOLE defined. If the netconsole script can find it
- in PATH or in the same directory, it will be used instead.
- For Linux, the network-based console needs special configuration.
- Minimally, the host IP address needs to be specified. This can be
- done either via the kernel command line, or by passing parameters
- while loading the netconsole.o module (when used in a loadable module
- configuration). Please refer to Documentation/networking/logging.txt
- file for the original Ingo Molnar's documentation on how to pass
- parameters to the loadable module.
- The format of the kernel command line parameter (for the static
- configuration) is as follows:
- netconsole=[src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]
- where
- src-port source for UDP packets
- (defaults to 6665)
- src-ip source IP to use
- (defaults to the interface's address)
- dev network interface
- (defaults to eth0)
- tgt-port port for logging agent
- (defaults to 6666)
- tgt-ip IP address for logging agent
- (this is the required parameter)
- tgt-macaddr ethernet MAC address for logging agent
- (defaults to broadcast)
- Examples:
- netconsole=4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc
- or
- netconsole=@/,@192.168.3.1/
- Please note that for the Linux networked console to work, the
- ethernet interface has to be up by the time the netconsole driver is
- initialized. This means that in case of static kernel configuration,
- the respective Ethernet interface has to be brought up using the "IP
- Autoconfiguration" kernel feature, which is usually done by defaults
- in the ELDK-NFS-based environment.
- To browse the Linux network console output, use the 'netcat' tool invoked
- as follows:
- nc -u -l -p 6666
- Note that unlike the U-Boot implementation the Linux netconsole is
- unidirectional, i. e. you have console output only in Linux.
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