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

[Kay Sievers]

On Wed, Mar 16, 2011 at 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?

The kernel will not recognize the prefix, add the default one and keep
the old prefix in the message:
  Before:
  $ echo '<14>text' > /dev/kmsg
  $ dmesg -r
  <4>[135159.594810] <14>text

After:
  $ echo '<14>text' > /dev/kmsg
  $ dmesg -r
  <14>[   50.750654] text

Kay