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@@ -44,11 +44,36 @@ 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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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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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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+
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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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+
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+ ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2
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+
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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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+
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NOTE: the network device (eth1 in the above case) can run any kind
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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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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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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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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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+
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+ dmesg -n 8
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+
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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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+
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Netconsole was designed to be as instantaneous as possible, to
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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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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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from IRQ contexts as well, and does not enable interrupts while
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