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Diffstat (limited to 'Documentation/networking/netconsole.txt')
| -rw-r--r-- | Documentation/networking/netconsole.txt | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt index 1aaa7383e41..3c2f2b32863 100644 --- a/Documentation/networking/netconsole.txt +++ b/Documentation/networking/netconsole.txt @@ -3,6 +3,10 @@ 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 Please send bug reports to Matt Mackall <mpm@selenic.com> +and Satyam Sharma <satyam.sharma@gmail.com> + +Introduction: +============= This module logs kernel printk messages over UDP allowing debugging of problem where disk logging fails and serial consoles are impractical. @@ -13,6 +17,9 @@ 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: @@ -46,6 +53,67 @@ address. The remote host can run either 'netcat -u -l -p <port>' or syslogd. +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) + 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). + +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. |