The kernel will output messages from time to time. If you're on a console,
you might see them. Otherwise, you can look at them with the dmesg
command. Most systems also put them somewhere in /var/log somewhere:
Distro
location
Debian
/var/log/kern.log /var/log/messages
Most messages are benign, and might tell you something about your sound
card, or ethernet card when the driver got loaded. However, some
are signs of trouble. Messages which begin with Oops
or BUG() are covered elsewhere. Here are some other common messages:
Out of Memory: Killed process 1234 (foo)
This will happen when you're really out of memory. It
doesn't mean that you need more RAM, it probably means that you have
a runaway process,