Comment 3 for bug 1537211

On Sun, Jan 24, 2016 at 06:38:22PM -0000, Martin Pitt wrote:
> I'm quite aware that we don't write this any more, but why do we
> penalize every boot with this? What is realistically there that isn't in
> "udevadm info --export-db"?

Well, it's possible I may not have known about the existence of this command
;)

Two things that are relevant here:

 - there are various apport hooks that attach /var/log/udev to bug reports,
   so these are currently attaching stale data (if any); one way or the
   other this should get fixed for 16.04.
 - the --export-db output doesn't include timestamps - or even ordering
   information, which may be very important for debugging.

On Sun, Jan 24, 2016 at 06:40:24PM -0000, Martin Pitt wrote:
> If we want a full log with timestamps etc. I'm fine with providing a
> disabled service which does that. This could be enabled using the
> standard "systemctl enable udev-monitor", or also via the kernel command
> line if "debug" is given. But I am really resistant about writing this
> extra log file all the time without a good reason.

I'm not aware of any complaints about the impact on boot time of running
this job. It necessarily writes to tmpfs early in boot, which is fast and
doesn't interfere with I/O. It's copied to /var/log later in boot, once
we're past the critical path. I don't see a performance reason for not
always running this at boot, especially given the possible difficulties of
reproducing a particular boot-time failure later if the job wasn't already
enabled.