Documentation/networking/netconsole.rst

1 .. SPDX-License-Identifier: GPL-2.0
28 This module logs kernel printk messages over UDP allowing debugging of
31 It can be used either built-in or as a module. As a built-in,
43  netconsole=[+][r][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]
48 	src-port      source for UDP packets (defaults to 6665)
49 	src-ip        source IP to use (interface address)
51 	tgt-port      port for logging agent (6666)
52 	tgt-ip        IP address for logging agent
53 	tgt-macaddr   ethernet MAC address for logging agent (broadcast)
77 Built-in netconsole starts immediately after the TCP stack is
88    On distributions using a BSD-based netcat version (e.g. Fedora,
90    the -p switch::
92 	nc -u -l -p <port>' / 'nc -u -l <port>
96 	netcat -u -l -p <port>' / 'netcat -u -l <port>
102    socat udp-recv:<port> -
109 parameters reconfigured at runtime from a configfs-based userspace interface.
112 netconsole module (or kernel, if netconsole is built-in).
123 above) and are disabled by default -- they must first be enabled by writing
134 	enabled		Is this target currently enabled?	(read-write)
135 	extended	Extended mode enabled			(read-write)
136 	release		Prepend kernel release to message	(read-write)
137 	dev_name	Local network interface name		(read-write)
138 	local_port	Source UDP port to use			(read-write)
139 	remote_port	Remote agent's UDP port			(read-write)
140 	local_ip	Source IP address to use		(read-write)
141 	remote_ip	Remote agent's IP address		(read-write)
142 	local_mac	Local interface's MAC address		(read-only)
143 	remote_mac	Remote agent's MAC address		(read-write)
144 	transmit_errors	Number of packet send errors		(read-only)
148 a target can be updated or not -- you can modify the parameters of only
184 ----------------
195  mkdir userdata/foo
196  echo bar > userdata/foo/value
206  12,607,22085407756,-;This is a message
207   foo=bar
220  mkdir userdata/foo
221  echo bar > userdata/foo/value
227  12,607,22085407756,-;This is a message
228   foo=bar
248 -------------------------------------
256 To enable task name auto-population::
269   12,607,22085407756,-;This is a message
276 ------------------------------------------
280 (version) auto-population feature, which appends the kernel release information
283 To enable the release auto-population::
290   12,607,22085407756,-;This is a message
291    release=6.14.0-rc6-01219-g3c027fbd941d
301 --------------------------------------
308 To enable the CPU number auto-population::
321   12,607,22085407756,-;This is a message
329    both keys will be reported, with the kernel-populated entry appearing after
332      # User-defined CPU entry
333      mkdir -p /sys/kernel/config/netconsole/target1/userdata/cpu
338      12,607,22085407756,-;This is a message
340       cpu=42    # kernel-populated value
360  6.4.0,6,444,501151268,-;netconsole: network logging started
370  ncfrag=<byte-offset>/<total-bytes>
375  6,416,1758426,-,ncfrag=0/31;the first chunk,
376  6,416,1758426,-,ncfrag=16/31; the 2nd chunk.
397 	ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2
403    default gateway (you may use /sbin/route -n to find it out) as the
420 	dmesg -n 8
425    dmesg(8) man page and Documentation/admin-guide/kernel-parameters.rst
433 only IP networks, UDP packets and ethernet devices are supported.