[systemd-devel] systemd-logger and external syslog daemon

[Lennart Poettering]

On Wed, 16.03.11 07:18, Michael Biebl (mbiebl at gmail.com) wrote:

> 
> 2011/3/16 Lennart Poettering <lennart at poettering.net>:
> > On Sat, 12.03.11 16:31, Andrey Borzenkov (arvidjaar at mail.ru) wrote:
> >
> 
> >>
> >> Attached patch preserves full syslog facility marker and simply emits
> >> it back. So userspace is free to feed any facility it deems
> >> appropriate, not only LOG_USER.
> >
> > This is a good approach. Kay has independently prepped a patch for this
> > now and it is already on its way into the kernel. It is hence very
> > likely that pretty soon there's no reason anymore to strip the facility
> > from the log messages before echoing them into /proc/kmsg.
> >
> > As soon as that patch is in the standard kernel I'll fix systemd to no
> > longer strip the facility. Kay will do the same for udev. And Harald
> > hopefully for Dracut too. And then all messages should contain the same
> > amount of information regardless which way the took to the syslog
> > daemon: directly via the /dev/log socket, or indirectly via the kmsg queue.
> 
> What happens if you run udev/dracut/systemd on a kernel without this patch?

You mean a new udev/dracut/systemd on an old kernel? The messages they
print would look a bit weird if they are used together with log msg
timestamping the way the kernel does it, since the kernel doesn't
recognize the prefix. (See Kay's post about this). But besides these
cosmetic issues nothing should really go wrong.

(I wonder if we can find a nice way to detect whether the kernel is new
enough for this, so that we could strip the facility automatically for
older ones. Explcitily checking for kernel versions at runtime is evil
though... I can't think of a good way though...)

Lennart

-- 
Lennart Poettering - Red Hat, Inc.