Documentation/networking/netconsole.rst

1 .. SPDX-License-Identifier: GPL-2.0
29 It can be used either built-in or as a module. As a built-in,
32 capture of early kernel panics, it does capture most of the boot
41  netconsole=[+][r][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]
46 	src-port      source for UDP packets (defaults to 6665)
47 	src-ip        source IP to use (interface address)
49 	tgt-port      port for logging agent (6666)
50 	tgt-ip        IP address for logging agent
51 	tgt-macaddr   ethernet MAC address for logging agent (broadcast)
71 Built-in netconsole starts immediately after the TCP stack is
82    On distributions using a BSD-based netcat version (e.g. Fedora,
84    the -p switch::
86 	nc -u -l -p <port>' / 'nc -u -l <port>
90 	netcat -u -l -p <port>' / 'netcat -u -l <port>
96    socat udp-recv:<port> -
103 parameters reconfigured at runtime from a configfs-based userspace interface.
106 netconsole module (or kernel, if netconsole is built-in).
117 above) and are disabled by default -- they must first be enabled by writing
118 "1" to the "enabled" attribute (usually after setting parameters accordingly)
128 	enabled		Is this target currently enabled?	(read-write)
129 	extended	Extended mode enabled			(read-write)
130 	release		Prepend kernel release to message	(read-write)
131 	dev_name	Local network interface name		(read-write)
132 	local_port	Source UDP port to use			(read-write)
133 	remote_port	Remote agent's UDP port			(read-write)
134 	local_ip	Source IP address to use		(read-write)
135 	remote_ip	Remote agent's IP address		(read-write)
136 	local_mac	Local interface's MAC address		(read-only)
137 	remote_mac	Remote agent's MAC address		(read-write)
140 The "enabled" attribute is also used to control whether the parameters of
141 a target can be updated or not -- you can modify the parameters of only
142 disabled targets (i.e. if "enabled" is 0).
146  cat enabled				# check if enabled is 1
147  echo 0 > enabled			# disable the target (if required)
151  echo 1 > enabled			# enable target again
157 Netconsole targets defined at boot time (or module load time) with the
162 Let's suppose you have two netconsole targets defined at boot time::
177 ----------------
180 dynamic configuration enabled. User data entries can be modified without
181 changing the "enabled" attribute of a target.
199  12,607,22085407756,-;This is a message
220  12,607,22085407756,-;This is a message
244 is set to 1, extended console support is enabled. An example boot
254 If 'r' (release) feature is enabled, the kernel release version is
257  6.4.0,6,444,501151268,-;netconsole: network logging started
267  ncfrag=<byte-offset>/<total-bytes>
272  6,416,1758426,-,ncfrag=0/31;the first chunk,
273  6,416,1758426,-,ncfrag=16/31; the 2nd chunk.
294 	ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2
300    default gateway (you may use /sbin/route -n to find it out) as the
317 	dmesg -n 8
319    or by specifying "debug" on the kernel command line at boot, to send
321    can also be set using the "loglevel" kernel boot option. See the
322    dmesg(8) man page and Documentation/admin-guide/kernel-parameters.rst