I've changed the topic title to better reflect what the problem was.
I've got a recent syslog-ng set up with the logging .conf from the Security Howto,
Section 3.d., and I'm seeing kernel Errors (that scroll by at boot-up) going into /var/log/syslog
as expected.
But on the boot-up scrolling screen, I'm seeing some sort of 'long line', possibly
a Warning, from possibly a driver, something about LNXSYSTM/ ... and then some
140 characters, with a BAT0 near the end, which (grep -R BAT0 /var/log/*)
isn't in the logs.
I'd like to see those messages in the logs, so that I can paste them here in the
Forums.

