A while back I posted a Netconsole tutorial for how to capture Linux kernel debugging messages from a crashing machine. I’ve refined the instructions down to three scripts and three commands, which are after the break.
Netconsole is a powerful Linux kernel debugging tool. The dmesg output from a machine under test is transferred over an ethernet link (via UDP packets) to another machine. That means that you can see the debugging messages from the test machine on the screen of another machine. Netconsole isn’t good for debugging early kernel panics, but it is very useful if your new kernel driver hangs your system.