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b5427c2717
Based upon initial work by Keiichi Kii <k-keiichi@bx.jp.nec.com>. This patch introduces support for multiple targets, independent of CONFIG_NETCONSOLE_DYNAMIC -- this is useful even in the default case and (including the infrastructure introduced in previous patches) doesn't really add too many bytes to module text. All the complexity (and size) comes with the dynamic reconfigurability / userspace interface patch, and so it's plausible users may want to keep this enabled but that disabled (say to avoid a dependency on CONFIG_CONFIGFS_FS too). Also update documentation to mention the use of ";" separator to specify multiple logging targets in the boot/module option string. Brief overview: We maintain a target_list (and corresponding lock). Get rid of the static "default_target" and introduce allocation and release functions for our netconsole_target objects (but keeping sure to preserve previous behaviour such as default values). During init_netconsole(), ";" is used as the separator to identify multiple target specifications in the boot/module option string. The target specifications are parsed and netpolls setup. During exit, the target_list is torn down and all items released. Signed-off-by: Satyam Sharma <satyam@infradead.org> Signed-off-by: Keiichi Kii <k-keiichi@bx.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
89 lines
3.6 KiB
Plaintext
89 lines
3.6 KiB
Plaintext
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started by Ingo Molnar <mingo@redhat.com>, 2001.09.17
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2.6 port and netpoll api by Matt Mackall <mpm@selenic.com>, Sep 9 2003
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Please send bug reports to Matt Mackall <mpm@selenic.com>
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This module logs kernel printk messages over UDP allowing debugging of
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problem where disk logging fails and serial consoles are impractical.
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It can be used either built-in or as a module. As a built-in,
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netconsole initializes immediately after NIC cards and will bring up
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the specified interface as soon as possible. While this doesn't allow
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capture of early kernel panics, it does capture most of the boot
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process.
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It takes a string configuration parameter "netconsole" in the
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following format:
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netconsole=[src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr]
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where
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src-port source for UDP packets (defaults to 6665)
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src-ip source IP to use (interface address)
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dev network interface (eth0)
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tgt-port port for logging agent (6666)
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tgt-ip IP address for logging agent
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tgt-macaddr ethernet MAC address for logging agent (broadcast)
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Examples:
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linux netconsole=4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc
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or
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insmod netconsole netconsole=@/,@10.0.0.2/
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It also supports logging to multiple remote agents by specifying
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parameters for the multiple agents separated by semicolons and the
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complete string enclosed in "quotes", thusly:
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modprobe netconsole netconsole="@/,@10.0.0.2/;@/eth1,6892@10.0.0.3/"
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Built-in netconsole starts immediately after the TCP stack is
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initialized and attempts to bring up the supplied dev at the supplied
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address.
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The remote host can run either 'netcat -u -l -p <port>' or syslogd.
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WARNING: the default target ethernet setting uses the broadcast
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ethernet address to send packets, which can cause increased load on
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other systems on the same ethernet segment.
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TIP: some LAN switches may be configured to suppress ethernet broadcasts
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so it is advised to explicitly specify the remote agents' MAC addresses
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from the config parameters passed to netconsole.
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TIP: to find out the MAC address of, say, 10.0.0.2, you may try using:
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ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2
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TIP: in case the remote logging agent is on a separate LAN subnet than
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the sender, it is suggested to try specifying the MAC address of the
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default gateway (you may use /sbin/route -n to find it out) as the
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remote MAC address instead.
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NOTE: the network device (eth1 in the above case) can run any kind
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of other network traffic, netconsole is not intrusive. Netconsole
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might cause slight delays in other traffic if the volume of kernel
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messages is high, but should have no other impact.
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NOTE: if you find that the remote logging agent is not receiving or
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printing all messages from the sender, it is likely that you have set
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the "console_loglevel" parameter (on the sender) to only send high
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priority messages to the console. You can change this at runtime using:
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dmesg -n 8
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or by specifying "debug" on the kernel command line at boot, to send
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all kernel messages to the console. A specific value for this parameter
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can also be set using the "loglevel" kernel boot option. See the
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dmesg(8) man page and Documentation/kernel-parameters.txt for details.
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Netconsole was designed to be as instantaneous as possible, to
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enable the logging of even the most critical kernel bugs. It works
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from IRQ contexts as well, and does not enable interrupts while
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sending packets. Due to these unique needs, configuration cannot
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be more automatic, and some fundamental limitations will remain:
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only IP networks, UDP packets and ethernet devices are supported.
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