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diff --git a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt deleted file mode 100644 index 296ea00fd3eb..000000000000 --- a/Documentation/networking/netconsole.txt +++ /dev/null @@ -1,210 +0,0 @@ - -started by Ingo Molnar <mingo@redhat.com>, 2001.09.17 -2.6 port and netpoll api by Matt Mackall <mpm@selenic.com>, Sep 9 2003 -IPv6 support by Cong Wang <xiyou.wangcong@gmail.com>, Jan 1 2013 -Extended console support by Tejun Heo <tj@kernel.org>, May 1 2015 - -Please send bug reports to Matt Mackall <mpm@selenic.com> -Satyam Sharma <satyam.sharma@gmail.com>, and Cong Wang <xiyou.wangcong@gmail.com> - -Introduction: -============= - -This module logs kernel printk messages over UDP allowing debugging of -problem where disk logging fails and serial consoles are impractical. - -It can be used either built-in or as a module. As a built-in, -netconsole initializes immediately after NIC cards and will bring up -the specified interface as soon as possible. While this doesn't allow -capture of early kernel panics, it does capture most of the boot -process. - -Sender and receiver configuration: -================================== - -It takes a string configuration parameter "netconsole" in the -following format: - - netconsole=[+][src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr] - - where - + if present, enable extended console support - src-port source for UDP packets (defaults to 6665) - src-ip source IP to use (interface address) - dev network interface (eth0) - tgt-port port for logging agent (6666) - tgt-ip IP address for logging agent - tgt-macaddr ethernet MAC address for logging agent (broadcast) - -Examples: - - linux netconsole=4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc - - or - - insmod netconsole netconsole=@/,@10.0.0.2/ - - or using IPv6 - - insmod netconsole netconsole=@/,@fd00:1:2:3::1/ - -It also supports logging to multiple remote agents by specifying -parameters for the multiple agents separated by semicolons and the -complete string enclosed in "quotes", thusly: - - modprobe netconsole netconsole="@/,@10.0.0.2/;@/eth1,6892@10.0.0.3/" - -Built-in netconsole starts immediately after the TCP stack is -initialized and attempts to bring up the supplied dev at the supplied -address. - -The remote host has several options to receive the kernel messages, -for example: - -1) syslogd - -2) netcat - - On distributions using a BSD-based netcat version (e.g. Fedora, - openSUSE and Ubuntu) the listening port must be specified without - the -p switch: - - 'nc -u -l -p <port>' / 'nc -u -l <port>' or - 'netcat -u -l -p <port>' / 'netcat -u -l <port>' - -3) socat - - 'socat udp-recv:<port> -' - -Dynamic reconfiguration: -======================== - -Dynamic reconfigurability is a useful addition to netconsole that enables -remote logging targets to be dynamically added, removed, or have their -parameters reconfigured at runtime from a configfs-based userspace interface. -[ Note that the parameters of netconsole targets that were specified/created -from the boot/module option are not exposed via this interface, and hence -cannot be modified dynamically. ] - -To include this feature, select CONFIG_NETCONSOLE_DYNAMIC when building the -netconsole module (or kernel, if netconsole is built-in). - -Some examples follow (where configfs is mounted at the /sys/kernel/config -mountpoint). - -To add a remote logging target (target names can be arbitrary): - - cd /sys/kernel/config/netconsole/ - mkdir target1 - -Note that newly created targets have default parameter values (as mentioned -above) and are disabled by default -- they must first be enabled by writing -"1" to the "enabled" attribute (usually after setting parameters accordingly) -as described below. - -To remove a target: - - rmdir /sys/kernel/config/netconsole/othertarget/ - -The interface exposes these parameters of a netconsole target to userspace: - - enabled Is this target currently enabled? (read-write) - extended Extended mode enabled (read-write) - dev_name Local network interface name (read-write) - local_port Source UDP port to use (read-write) - remote_port Remote agent's UDP port (read-write) - local_ip Source IP address to use (read-write) - remote_ip Remote agent's IP address (read-write) - local_mac Local interface's MAC address (read-only) - remote_mac Remote agent's MAC address (read-write) - -The "enabled" attribute is also used to control whether the parameters of -a target can be updated or not -- you can modify the parameters of only -disabled targets (i.e. if "enabled" is 0). - -To update a target's parameters: - - cat enabled # check if enabled is 1 - echo 0 > enabled # disable the target (if required) - echo eth2 > dev_name # set local interface - echo 10.0.0.4 > remote_ip # update some parameter - echo cb:a9:87:65:43:21 > remote_mac # update more parameters - echo 1 > enabled # enable target again - -You can also update the local interface dynamically. This is especially -useful if you want to use interfaces that have newly come up (and may not -have existed when netconsole was loaded / initialized). - -Extended console: -================= - -If '+' is prefixed to the configuration line or "extended" config file -is set to 1, extended console support is enabled. An example boot -param follows. - - linux netconsole=+4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc - -Log messages are transmitted with extended metadata header in the -following format which is the same as /dev/kmsg. - - <level>,<sequnum>,<timestamp>,<contflag>;<message text> - -Non printable characters in <message text> are escaped using "\xff" -notation. If the message contains optional dictionary, verbatim -newline is used as the delimeter. - -If a message doesn't fit in certain number of bytes (currently 1000), -the message is split into multiple fragments by netconsole. These -fragments are transmitted with "ncfrag" header field added. - - ncfrag=<byte-offset>/<total-bytes> - -For example, assuming a lot smaller chunk size, a message "the first -chunk, the 2nd chunk." may be split as follows. - - 6,416,1758426,-,ncfrag=0/31;the first chunk, - 6,416,1758426,-,ncfrag=16/31; the 2nd chunk. - -Miscellaneous notes: -==================== - -WARNING: the default target ethernet setting uses the broadcast -ethernet address to send packets, which can cause increased load on -other systems on the same ethernet segment. - -TIP: some LAN switches may be configured to suppress ethernet broadcasts -so it is advised to explicitly specify the remote agents' MAC addresses -from the config parameters passed to netconsole. - -TIP: to find out the MAC address of, say, 10.0.0.2, you may try using: - - ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2 - -TIP: in case the remote logging agent is on a separate LAN subnet than -the sender, it is suggested to try specifying the MAC address of the -default gateway (you may use /sbin/route -n to find it out) as the -remote MAC address instead. - -NOTE: the network device (eth1 in the above case) can run any kind -of other network traffic, netconsole is not intrusive. Netconsole -might cause slight delays in other traffic if the volume of kernel -messages is high, but should have no other impact. - -NOTE: if you find that the remote logging agent is not receiving or -printing all messages from the sender, it is likely that you have set -the "console_loglevel" parameter (on the sender) to only send high -priority messages to the console. You can change this at runtime using: - - dmesg -n 8 - -or by specifying "debug" on the kernel command line at boot, to send -all kernel messages to the console. A specific value for this parameter -can also be set using the "loglevel" kernel boot option. See the -dmesg(8) man page and Documentation/admin-guide/kernel-parameters.rst for details. - -Netconsole was designed to be as instantaneous as possible, to -enable the logging of even the most critical kernel bugs. It works -from IRQ contexts as well, and does not enable interrupts while -sending packets. Due to these unique needs, configuration cannot -be more automatic, and some fundamental limitations will remain: -only IP networks, UDP packets and ethernet devices are supported. |